There may be a thousand videos out there on TH-cam on "how to machine", but Joe I gotta tell ya, short of actually doing an actual apprenticeship your videos are far and away the best resource for learning the tricks of the trade. Bravo. Thanks, and looking forward to any more tips you've got to share.
Hi Joe, Pierre has taught me the straight in method, no issues on the Graziano. I just ease up on the DOC the deeper you go. Great Video as always, thanks
I've seen videos saying both 29 and 30 degrees. Some by South bend, (old!) and one this morning saying 30 degrees also really old. I see that there is machinists on both sides of the isle. Myself I still struggle at times getting my cutters exactly perfect, so anthing that close I am perfectly happy. I'm glad that we have these great videos so I can help hone my skills. Thanks Joe for the effort, its appreciated.
Hello Joe I just wanted to say I really appreciate all of your videos I am about to Retire from a 32 year career in Law enforcement and I am thinking about getting a lathe and starting to learn metal working Something that I have always been interested in. Your videos are very educational and inspiring to me Thanks again JPD
I'm 70 years old, and I always learn something from Joe P. I Never miss a JP video.! I hope any apprentices you have, realize how fortunate they are. Keep up the good work, it's a pleasure to watch the theory as well as the practice. Best Regards Mike N
Hi Joe, when I saw the title of this video, I knew it was going to generate a huge 'mail bag' and it did not disappoint. This is what is great about the community, absorbing info from multiple sources before synthesising a work plan. Mr. Bloom would be proud of you!! Kindest regards from Bonnie Scotland. Joe.
Hi Joe, thanks for the interesting and informative video. Another technique that I like to use, especially when picking up an existing thread, is to set the compound at 90 deg (parallel to the bed), and to advance the cross slide for the depth of cut, say for example .010", then advance the compound by half of that amount, in this example, .005". This gives a tool position change close enough to what a 29 deg compound advance would give (the correct compound advance in my example would be .0055"). The amount of cross slide advance directly compares with the fish tail gauge values, and a final light pass of .001" or .0005" without any compound advance should complete the thread form. This technique also allows precise control of the form of the thread root. With a coarse thread, for example 1" x 8 TPI, the root flat should be .0313" (P/4). This can be accomplished with advancement of the compound only. Using the 29 deg method, an overly deep root cut or special tool tip grinding would be required. Thanks again for your good work.
A few months back I experimented with this on a Sunday afternoon. I did two threads on the same piece of steel. One using the 28.5 degree and one just advancing straight in. I could not see any difference in the threads. I even examined them with a usb microscope and they look very much alike. Then some viewers told me that overseas plunge threading is normal and they had never heard of the 29.5 degree stuff. So I can certainly vouch for your facts, from my non-machnist experience. I have been threading using the plunge method since. Thanks for the great video.
I plunge everything too. I did this video to illustrate chip load and tool geometry impact on the cut. I hope the message came across. Thanks for watching.
Thanks Joe. Very interesting. I always wondered about the criticality of 29.5, but never came across a demonstration of the logic involved. Very cool, thanks again...
Mr. Pieczynski; It's obvious you have a wealth of first hand experience in the craft. Thank you for your shop advice, and excellent illustrations. Being a retired lifelong machinist, I still have a love for the trade. Before I retired, I thought of myself as an accomplished machinist. Watching your videos has been really enlightening, even for an old dog. Just one thing. When setting the compound for a 60° thread, I must say I favor 29-1/2°. In my experience, especially on older equipment, I've had "scuffing" on the trailing flank, especially with carbide. (@ 30°). Tool life is shortened, due to chipping. Chips seem to be dragged past the trailing cutting edge, making a poor finish. Your equipment looks to be top-notch. You may not have this problem. Much of my experience was on old rats. Early 1940's machines, especially war production board tools. That's where I learned the trade. Mark
Joe, wondering if you could ever get around to making a full video on threading. From start to finish. Showing the full tamali of how you go about it, from putting it in the chuck to testing the finished thread for fit. Be a real treat for a beginner learning from the master how to do it the proper way.
I'm only a hobbyist, but I've always thought machining and the techniques required should be based on logic, facts, and physics. So great explanation of what's really happening Joe. Since everything is basically rubber and nothing made no matter how heavily built is ever completely rigid, plus the stack up of tolerances that allow the slides to move even on a high end brand new tool room lathe, plus the tool and machine parts flexing under cutting forces. That would tend to force the tool slightly off that 29-29.5 degree path and to the right anyway. So setting the top slide to a certain angle is still only going to be approximate to what it will actually be during a threading operation. As the thread depth deepens the cutting loads go up on the left side of the tool tip and the tool and machine parts will flex even more to the right. That angled top slide does help on my lighter lathe simply for the reasons you've pointed out. Mine just doesn't like straight in threading on larger thread depths.
Your teaching ability is so on point! When im having trouble fully grasping certain processes and you make a video about it, I always get it right away. Keep up the good work brother it is much appreciated 👍🏻🇺🇲
Wow that's great content! Thanks for that. "29.5 deg." never made a lick of sense to me, but this is the definitive explanation why close to 30 but never over is the way to go. I never realized there was right side chip load even at 30 before, but it's clear now. I've plunge cut (0 deg) plenty of times, but 30 minus a smidge at half the chip load while still cutting the ENTIRE length of both sides is obviously the way to go. Never understood that until now. Love your channel!
Good demonstration Joe, and the PC model makes it easy to see. I do however think some of your comments below are biased to your own experience with thread cutting for 40 years. I've been doing it half of that and always used the compound angle infeed and it's what I know, and what I'm comfortable with. Muscle memory. Why should I change? Why is having my compound always set at 29.5 a waste of my time? I like keeping my cross slide set to zero on each pass and keeping up with the depth with the compound. It's what I'm used to and it's what I'll continue to use. The proof is that it works.
Hi Adam. Thanks for checking in. You are correct. I am a big advocate of plunge cutting threads. Its my comfort zone just like your offset compound is yours. In our job shop world of "time is money" I just wouldn't support one of my guys spending too much time trying to set the compound to a precision 29.5 degrees when a quick 25 or 27 is only going to afford .0002 more of a chip load. That is a waste of time. I hope you agree. The muscle memory comment is something I will never argue. I have supervised and trained many journeymen and apprentices during my career and know first hand, 10 guys will do the job 8 different ways and get the same result. As a foreman, sometime you just have to stand back and trust someone else's hands and experience. I personally have had tough industrial machinery at my disposal for the majority of my career and have cut threads so over constrained for military applications, that plunge cutting is the only option. The compound is used for pitch diameter control once a critical root diameter is achieved by the cross slide. You are right...a good final part made in a reasonable time is truly the proof. Take care Adam. Thanks for the comment.
Something I'll add is that on my lathes I always keep the compound set at 29.5 and the tool post indicated square to the work. The lathe is most always ready to cut threads at anytime. It's when I have to use the compound for other angles is when I spend more time changing it around. At my day job machining hydraulics rods is an everyday thing, so lots of thread cutting there. Using the compound infeed easily allows you to keep up with depth if you return the cross slide to zero each pass. Keeping up with straight infeed position each time is too much for me. To each there own, I just don't want someone saying the all to familiar "your doing it wrong" just because there's more then one way to get the job done.
Hi Adam. I can understand everything you said. I too usually have my tool post indicated to zero, and usually have at least 1 tool holder where the vertical tool registration surface is also ground to zero. Thats my thread block. Your environment is perfect for your setup and technique. My latest video was more to address everyone's belief that there is no right side load with the 29 degree method. I think I successfully proved that is an incorrect statement. I am more than open to new methods and ways. Its what helps us all grow and learn. I would be the last person to ever say, you're doing it wrong' just because you are not doing it my way. We all have our techniques. Stick with what works and gets the job done, but keep an open mind for the next best thing. Regards JP
Joe Pieczynski. Abomb's Monarch, and mine also, has a return lock on the crossfeed dial that's designed for single point threading. It allows you to set the crossfeed at the major diameter of the thread, then back out of the cut, and return the carriage to start the next pass with a positive stop on the crossfeed, and dial in the depth of the next cut on the compound. The exact depth of the cut can be determined with a little trig, or read direct from an indicator. BTW, my 1946 Monarch CW 18x54 has 29 1/2 degrees plainly marked on the compound protractor. peace-out..Tc
Im 60 and got so scared of machines in HS i couldnt become a machinist. too much too fast. But I recently had a stroke and the logical part of my brain is starting to learn again. Boy I wish my machine shop teacher was as good as you. with a damaged brain I understand more than he taught. Thanks Joe
Mr Joe, u explain so my 4 year old daughter can understand. Some ppl get lost quick with extra words. Btw U are the only Yutube Lathe I watch. Do some CNC Programming . Thank u sir.
Joe, well played. I just got to watch this one (3 years late!), and it is probably the best representation of tool movement and cutter engagement I have seen on the single point threading subject. The computer assisted tool trajectory image made the video. My background is in engineering, and this is spot on. This should be required content for any apprentice learning to single point. This has other applications as well, as tool trajectory is always a consideration in any machining application although not always as critical as in threading. Again, outstanding rendition and simulation.
I enjoyed seeing your computer modeling skills. As a T&D apprentice this theory was explained to me by an old French t&d maker. He was a master. He demonstrated cutting (moderate diameter) threads to size in a total of 3-4 cuts! Scared the crap out of me. He could do it every time. All HSS in those days. Time was money. Wouldn't tolerate scrapping 5 thou or so per pass. Rip Emile.
Thanks Michael. My modeling skills are solid on Pro-E. I enjoy it. I've go some crazy model in the files. Take a look at my 'Modeling a gage perfect thread" video. If you think about tool contact, your first thread cut can be very deep because the tool contact is so small. No reason to grow old running a thread.
I am new to all of this and as yet have not tried to cut threads because I could not picture the reason for the 29.5 angle. This video cleared up that for me. Thank you so very much. Oh, I am trying to teach my self and really have no one to ask about things like this. Thanks again.
Joe, i would like to start by thanking you for so much amazing info, you have helped me in a huge way! Second, if i could split my insert it could still be done, if your compound is set at 30 degrees because of the fact that it is a helical movement, you do not contact the right side of the tool. Your pc model is only good if the tool is not moving to the left or right. If the tool is stationary and the part is rotating then yes! That would be the effects of cutting. But you are not plunging! You are effectively scraping the surface of the part as it rotates and the tool moves from one side to the other. If the right side(using your model that is threading from right to left) of the tool is cutting then i would be forced to say that your tool is not moving at the right speed, i.e to slow. I can't wait to hear back from you. Thank you again so much!
Greetings. I have to respectfully disagree with your conclusion. Any advancement of the tool towards center, compound or cross slide, plunges the tip of the tool into the part. It is impossible to advance a tool into any material and not translate the area of the tip of the tool as the cut profile. If you were to split a threading tool and set your compound to 30 degrees, your incremental depth movements would have to be microscopic and you would have to make 100 passes or one side of your thread profile would be serrated. The computer model proves this without a doubt. Doing that is not like back turning a 30 degree taper. Totally different.
I am rather new to machining especially compared to your career in machining so i am rather stumped on this, so if you are strictly talking about the plunge of the tool into the part, at what point of threading do you ever plunge the tool in? That wouldn't leave you with a thread, that would leave a groove.
@@zachjohnson3261 i see why you are confused, but it's difficult to explain. the way you talk, you are thinking along the lines of, even when you're not threading, your still threading, because normal turning is technically still threading, because you're always cutting a spiral, it's just that a actual thread is just really coarse turning, say a hundred thousandths per rev instead of three, but where threading differs from turning is that 1. you are leaving material on the o.d.,the material that forms the thread, and 2. the tool is clocked to the part, and is "retracing it's footprints", it does not move away from the left side, if it did, the root of the thread would keep getting wider with every pass, the left side of the tool is locked on a tangent axis to the left side. think of it this way, when you do you'r first pass, the whole tip of the tool is cutting, on both sides, the second pass is exactly the same as the first, the tip of the tool is still cutting on both sides, the only difference is that on the second pass, you're using the right side of the tool to make the cut wider.
This is correct, same as if you are reducing the diameter of a shaft with a conventional slide feed cut. Are you cutting off both edges of the cutter then? No, not really. The left side of the cutter is removing the material, the front tip of the cutter is behind the material that was already lifted by the leading edge of the cutter. Equally if you are using a parting tool to plunge 90 degrees into a part, is the side of the cutter cutting? again, no not really, it is behind the leading edge of the tool that has already lifted the material. The main point of running at a 29.5 degree is to keep the tool pressure holding the carriage lash tight to the lead screw, while reducing tool pressure at the bit. Look at the difference in the swarf coming off a straight threading cut vs one where you are feeding the compound cutting off "one side", huge difference.
I love this content. I spent a semester at WA state in a machine work class and was always told 29.5. A decade later I’m still doing hobby job theads like barrels with that same teaching with great success. Keep up the great content!
Hi Joe; This very subject has probably started many arguments over the years. I'm saying that as a humorous aside, not to lessen the info in your video, which I enjoyed. I always enjoy being right. :) I do agree with you, no matter the angle, both sides of the tool cut, and I was convinced of that before your excellent computer demo. Well done on that! The 30 deg angle does help small or old machines, and that is probably where the practice originates. Like one comment mentioned, it likely made a difference to old forged tools, as well as old machines even when they were new, considering babbitt bearings and less than perfect gibs. Back in the steam power days. One thing the 30 deg angle offers is to effectively increase the resolution of the infeed on the compound if you use a little trig to figure it out. Other than that, meh, plunge it and cut that thread. Thanks for another well presented vid!
Thank you Joe, i never really understood this before. Understanding the the tip as a form tool was the ah ha moment! As was the fact that you can form a perfectly good thread with a straight plunge, so it follows if 0 degs works and 30 deg works 29 or 29.5 deg should work with no problem , clearly it does.
Hi Joe, English born and engineered here, and I like your analysis and explanation, but to be fair, in our neck of the woods...we were never taught that using compound projection toolpath totally eliminated rear side cutting (or rubbing). Quite the opposite in fact. We were always taught that there would be material contact via depth of cut, however, this was always spoken as "good practice". The reason being that the root form is executed more securely if the tool is cutting around the tip or root of the thread, be it a flat form or radii form. To suggest that "snugging" the root form is a stronger and perfectly defined process. However we we also taught that upon forming the "root", minimal contact on the trailing edge was also paramount... I kinda get what you are 'myth busting' about and agree, but as I say... My educators never claimed that no tool contact was made on the trailing edge...rather just to keep it to the root form for rigity in cut etc...
Thanks Joe, first time single point thread cutting, this coming weekend, can't even begin to do that without checking you out. Thanks as always Sir, you've more than helped and inspired as always
Thanks for another great video. One thing I learned from watching Bruce Wittham is that machinists in a lot of countries outside the US plunge cut threads using the cross slide only with no problems. I'm going to stick with 29.5º because that what I've always done and the chip load is low. Chris
It's not a US versus the rest of the world issue, if memory serves the really early South bend books showed going straight in. Having said that, go with what works for you or you are comfortable with, that way you will make less errors, even if it is not necessarily the best way.
Hi Joe, good video.Took me back to the mid 70's when I was training in UK. I was taught to do Metric and Whitworth (had half nut drop out during finishing cut on a 1" Whitworth, wasn't good, still got a scar . I didn't know any better back then ) 'We' were taught to use anything from 10 to 27.5 degrees or just plunge cut forsmaller dia. 55 degree Whitworth threads. T he difference on 'shadow graph' was noticeable, and looked like north face of the Eiger when magnified 500 times. (Surprisingly, Honda motorcycles used Whitworth threads back then on some components, I used to measure 'everything and anything' to practice) You mentioned tool was likely to rub rather than cut, often it does. even with industrial machines which are way bigger plus more rigid. That was the reasoning behind using smaller angles, get tool loading reduced but not removed. It was obvious both sides of tool were cutting even at 27.5 deg. Only subscribed last week, jobbing machine shop does more interesting things than factory machining.
Thank you George Carlson!!! I apparently have a Chinese (ENCO, should have guessed it) lathe. As per your post, I set my compound slide at 60* and VIOLA!! Perfect cut! Since the graduation tag only reads to 45* in each direction, I rotated my slide to 30* and scribed a mark at "0" then rotated it on around until 30* aligned with my scribed mark. Works like a dream. Out of all the thread cutting videos I have watched, I don't remember anyone mentioning the diff in compound slide markings between different manufacturers. Thanks again!
Old topic but YT recommended it so I researched it. I usually just go straight in as I can't be bothered to move my top slide off its carefully set to parallel position. Years ago I did a series of tests cutting a 1.5mm pitch thread in 303 stainless going straight in and with offset top slide using the same full form insert. Looking at the results under a microscope I could not tell which was which as they looked identical. Having said that, today I cut several 1 5/16" by 9TPI threads in Aluminium on an unpowered Myford, don't ask, and set the top slide over just to give my left arm a chance of being able to lift a beer bottle afterwards.
Hello Master Joe, I only have a small lathe and not all these magnificent machines you can use. But your ideas, principles and methods are great and I adapt them to my small shop. You explain everything very well. Thanks a LOT. Stay Healthy, Pierre
I truly love your videos Mr. Pie. You're good nature and humor, the consistency of your explanations and demonstrations, and thoroughness of information is what really makes them a pleasure to watch. It's almost as good as being in shop class with the guys. I particularly enjoy your old school utilization of your dry erase board and filming your computer screen. If it ain't broke, don't fix it, right? With that said, regarding threading, I have very little experience with it and have a few questions. If your 60° HSS thread-form tool is set perpendicular to the workpiece, the cutting plane is ran parallel to the threads being cut, the cut is typically began from either a relief channel or from outside the part and ran into the cut itself, what does the angle of the Compound have to do with anything other than approximate measurements to get in the ballpark of your desired Pitch Diameter? Also, what methods do you use and recommend to set your tool height and Perpendicular to your workpiece?
Joe, thanks for the explanation. After watching your inverted tool video method of treading, I go strait in. If you take small bites, it works for me and I can use the cross slide DRO to get the required depth of cut.
Think that seems to prove once and for all a thread tool is a form tool and ALWAYS cuts on both sides. Setting the compound to 29 degrees etc only serves to REDUCE tool load on the right side of the tool ( when cutting towards the chuck ) Got it ! Thanks Joe I’m in Britain and have a small 4.5” smart+brown model A lathe iv cut various 55degree whitworth threads ( native to this machine ) just for fun mainly and have previously just cut them , filed them till a nut fits. Having watched your various threading videos I now plan to dial in my depth of cut with the cross slide at the extremity of the thread forming a “relief groove” then verify the pitch diameter with wires back out the 27degree compound then cut the thread using the compound only to hit the exact pitch diameter 1st time 🤞🏻 Great videos excellent content, well explained 👍🏻 Side note I think the inverted threading looks superb why doesn’t everyone do this ?? Unfortunately iv a screw on chuck and won’t be able to try this 🙈
Thanks Joe. I had been worried that if I wasn’t exactly 29 1/2 degrees, which on Asian machines may not be close, my thread would suffer. Your explanation takes away the anxiety. Thanks again, JB San Diego
I have abstract thought not all people do but I could see you computer program in my mind some time ago. I also looked at the chip the tool produced and you can see it is cutting on both sides the trailing side the least, there is no way it cant. Most if not all of the time I dive straight in anyway. I set the top slide/compound parallel with the cross slide. I back out and in with the cross slide and cut to depth with the compound slide. Plus as you do I do all of it going out not in. Works for me.LOL Thanks for the great non rehash BS videos we all see here way too often. Worth
Another good video Cap'n Although this was directed at Your Imperial Thread Cutting audience, we reckon it would be most applicable to our Metric threads as well. Putting the demo on CAD clearly shows the cutting angles perfectly Thanks again for showing and sharing aRM
I recently threaded with slightly less than 30 deg., but decided to try a smaller angle-- 15 deg. And surprisingly the cuts went smoother (reduced chatter) with the same light pass techniques. Sometimes, maybe it is many facets of the processes involved: tool, material, machine.. . and so on...
Thanks Joe for another thought provoking discourse ! My thoughts have always been that the area of metal which you identify as being removed by the right side of the tool is in fact removed by the left side, as the helix of the thread means that it is presented to the left face of the tool before it sees the right side, or am I wrong ? I can recall my college days, back in 70’s, when we did some investigations into cutting forces in machining operations. All machining is a tearing process, where the force generated at the tool cutting edge has to exceed the ultimate tensile strength of the material being cut, and it follows that the greater the length of cutting edge, the more load there is on the tool. To minimise the loads on the form tool, which is often quite a frail device, it made sense to only cut on one face, so that the flow of the chip was cleanly away from the tool cutting edge, and this was clearly demonstrated by less tool deflection and lowest power consumption. Plunging the tool into the work perpendicularly to its axis means that you are cutting on both faces and the two streams of chip come together and are compressed as they try to escape, which further increases the load on the tool tip beyond the expectation of that due to the doubling of the shear area. Furthermore, with a flat topped form tool, when you take into account the thread helix, the left side of the tool has some degree of positive top rake, whilst the right side of the tool has an equal amount of negative rake. This might be problematic when machining some materials . . . . It might give you a wry smile when I tell you that the machine which we carried out the tests on was a brand new Colchester Triumph 2000, fitted with a 3phase watt meter for measuring electrical power consumption and strain gauges on the tool holder, to measure the deflection of the tool ! Load on the tool eventually translates into wear at the cutting edge, as some exponential function, so any reduction keeps the tool sharp for longer and, on a batch run, makes for more quality threads, before a tip replacement is required. Now retired, my little 5 x 20 workshop lathe ( probably even older than me ! ) isn’t capable of dealing with a plunge cut, so I’m not too proud to set the compound slide over. To sum up, plunge cutting is fine, if your machine and tool set up are strong enough to take it, but on a production run, the economics of higher power consumption and increased tool failure might not yield the expected profits. As my college lecturer, himself a retired production engineer, was fond of reminding us “Gentlemen, our job is to make as much swarf, as fast as possible, because the customer only buys what’s left !” Apologies for this rambling dissertation ! Kind regards, Steve.
Done a lot of female, acme, double leed, left hand threads for limit torque operators in motorised valves. These were made of aluminized bronze. This stuff is hard and tough. You want to talk about wanting to chatter. The bores were not that big, and the nuts were fairly long, so good boring bar rigidity was never there. Typically, a general purpose acme at 28 degrees, so 14 on the compound. This stuff actually chattered worse on light cuts. Less tool pressure more harmonics, I suppose. So, I just started setting the compound at 90 and plunging straight back. Most were 2 sets of 2 at 4 threads per inch. So, slipping the nut was the norm. Anyway, with the compound at zero, I could fudge the tool forward and back, turn the lathe chuck very slowly by hand while engaged, and remove chatter marks when I was to depth. Engineering wanted a looser thread fit, so tolerance was not a problem as the minimum thread crest was not exceeded. Wow, that was 25 years ago.
Hey Joe Where you going with that……….I,ll stop that I was a production lathe operator back in the sixties and seventies.The setter would set up the machines,which were often capstan lathes or centre lathes and screw cutting was an everyday event. You really were spot on with the nerves when screw cutting but we just learned the tecnique and got on with it. The method you described here would have saved my premature ageing but as i was watching i wondered if you were brought up old school and used the old method of screw cutting first or did you develop this because of the nervous shake that would develop as you neared the under cut and had to stop the machine, remove the tool …..no i cant go on Keep up the good work, respect.
Great video, Joe. Thanks. I have used lathes for a couple of decades now but just as a self taught (trial and error) machinist, and I used that term very loosely. Mostly facing, turning and grooving. I am now needing to learn thread cutting. Following these instructions, the outcome of my efforts is a thread that more resembles a "buttress" thread. I have the correct TPI and have all but mastered the half-nut engagement (thanks for that video, as well) but with using the cross slide only for plunging and retraction and the compound set at 29-30 degrees, all my practice pieces come out with a very lopsided thread. The leading (cutting) edge actually appears to be 10-15 degrees and the trailing side appears to be about 35-50 degrees. I am using a 60* thread cutting insert and am cutting a 7/8"-9 external thread on PVC solid bar stock. I have also tried it with aluminum bar with same results. A nut will easily thread onto it but it just doesn't look good/correct. I don't know what I'm missing here.
Great video Joe let's hope it makes it clear for a lot of people. Personally my own experience when I first started in the trade 60 years ago I used to plunge straight in and trash the tools. (HSS on a manual engine lathe) breaking the very tip. Back then I never understand why. If you plunge straight in you have equal chip load on both sides with a tendency of the chips loading up and destroying the very small tip of your tool. 29 1/2°, I've used ever since an old timer explained why. Most of the cut is on the left side most of the chip curl away clean while the right side of the tool just barely skins but just enough to make it look good and clean and a lot easier on the tool.
Like this video proves, both sides still cut, and the tip is always working. Carbide like to be buried, but HSS may be different depending on the setup.
Thanks Joe. Love your videos, I checked this out using my own cad to hammer the concept into my brain. More than 30 degrees results in a stair step, less than 30 and the right side of the thread is either burnished or cut but thread is perfect just the same.
Just subscribed. Of coarse I started watching your videos in reverse order, but I will catch up. Well presented and to the point. Thanks Ed K. Cleve. Oh.
Like many I started with a SB 10K back in the late 60s and stayed with the way I was taught until you came along. I have a 3 horse 14-40 chinese machine I have had for 20 years. It does just fine with straight in threading, just do the scratch pass at final to clean up. do a lot of rifle barrels, threading, away from the shoulder is great, thanks and keep the info coming!
All this time I thought it was a bad setting on the compound, guess there must be another reason why it is raining frogs in my shop. Thanks for another excellent video.
Have to admit I didn't know what the 29-1/2 degree was for even tho I know that angle and I simply used the cross slide knob for threading. It'll be fun to see how my next threads turn out. Thanks Joe!
Dang Joe, thanks for the very informative video. Actually, the first of yours that I watched concerned threading with the toll upside down, spindle in reverse and cutting away from the head stock. I had to try it for myself, it sold me. Then I watched this video. OK....I hit the subscribe button. I like how you think and work.
Thank you Mr Joe for sharing your wealth of information and knowledge. I’m new to the machining game and your channel is my #1 source of education. I reset my brain to the plunge thread cutting after seeing your videos and trying for myself I realized how much better results I was getting compared to the compound feeding at 29. I wish I could try the reverse tool technique but I have an old ( 1944) south bend 9A with a threaded chuck. Thumbs way up to your channel and content!!
Don't completely abandon the compound approach since it does serve a purpose. On smaller diameter parts, the lower load can really help. Thanks for your positive support.
I never thought that 29.5 degrees was a solid angle but it was simply to lower tool pressure. I was taught to finish with a straight depth cut. Depending on material type maybe tenths or a couple of thousands. I Dig your videos, by the way. I've been machining for 30+ years off and on and sometimes I feel like I'm a boot camp in the Navy when I hear something new!
Thanks for the video Joe - very informative; however in addition, I'd like to see you do something similar explaining some of the calculations, terminology, tables, etc. that deal with how deep to advance your compound to achieve the proper thread depth, what is meant by "double depth of thread", thread types, what the numbers on the fish tale mean and how to they relate to compound depth, etc. Basically I'm asking for "basic" info that you pros have learned through experience and/or formal & informal education that us weekend hobbyist haven't had the benefit of. Also, the dial on my lathe's compound must be different from most machines. To set mine to 30 degrees I have to set the dial at 60, so to achieve 29.5 would I set to 59.5 or 60.5. :-) Thanks again!
28 people who downvoted this video should not be allowed anywhere near the lathe (or any other machine). Also, they should post their names here so those who read comments don't make a mistake of hiring them for any machine work, either.
Thank you. I'm just about finished seeing up a minilathe to start learning while refurbing the Sheldon. My first project is facing, turning and drilling only but the second one I want to try threading. I watched the video to get exactly the information you presented. I saw @Abom79 commented a few years ago and I have a lot of respect for the work he does but this is far more apropos for a beginner with a light, Chinese minilathe than the rigidity of the big machines he's running. If I run my first try, it won't be because I didn't do this correctly, thanks to you. :-)
Interesting video. I agree totally that as long as you don't exceed 30 you will get a good thread. One point someone once made was that if your last few passes are done by plunging with the cross slide, then any discrepancy caused by compound alignment becomes irrelevant, as the tool is acting as a form tool. One question - when using the reverse threading technique that you have shown, should the compound be set at the opposite angle to when you are threading conventionally? Eg. 29 degrees the other way?
I plunge everything. 100% of the time. I would suspect the compound setting should be the same for the inverted tool. One side would still be cutting, it would just be the trailing edge.
Excellent Video, I haven't bothered to set my compound at 29.5 for years, With modern tooling (Inserts) I just plunge straight in after ensuring that my tool is set perpendicular to the axis. I taught my students the same thing. THe only time I use the compound is when I am using high speed hand-ground tooling and then only if I am on the first cuts, when I get in deep and am neat finish size I do the last few thou's with a plunge cut, it kinda evens up the finish. Excellent Video dems of what I was taught years ago.
Hi Joe, Thanks for the excellent demonstration of a subject not well understood. I've cut many threads at 30 degree angle and straight in and both work well. However, there's one situation where a 29/30 degree angle produces superior threads than straight in. Lets say you're cutting a 1.00-8 thread in 304 SS, 4140, aluminum bronze, or other tough material. In that case an 8/10 degree positive side rake produces a smoother cut with less chatter than feeding straight in. Keep 'em coming.
yes Joe I have done it both ways on smaller threads my biggest problem is I get a lot of chatter and my Trent but I will keep trying Another great job thanks
Very clearly explained Sir. I have a small EW Stringer lathe that I am about to start cutting threads with. I could not understand the reason behind having the compound set at an angle. I do now. Thank you.
Great Info! I always use 29 degrees and have often wondered what the difference is between 29 and 30.....I always grind hi speed tools and was taught that the angle greatly minimizes the stress on the tool, part, and machine.. Mike in Louisiana
The reason you should cut at 29 is so you don't get a chip from each side feeding (and smashing) into each other on top of your tool especially on larger threads I can cut way more per pass this way and tools aren't breaking the reason we go 29 instead of 30 is to make sure to drag the right and keep nice profile and finish the last .005 I do straight in a couple fine passes heavy chips do not like to be fed straight in to each other especially on ss and any steels or harder metals brass you can feed straight if u want Thats all i have to say about that
Joe that digital model makes things so much more clear and answered a lot of questions in my old fart mind. Thanks for all the effort you put into your videos. I sure wish you would consider teaching some classes, hint hint.
As a backyard hobby machinist, I watch Joe's tips religiously and learn from every one of them. This video ignores a giant, checkered yellow, elephant in the room. Namely Joe's religion of threading in reverse and away from the headstock. I just made a custom BXA holder so I could get a left hand threading tool high enough to get the tip on center and cut a few threads on a new to me and in new condition 13x40 Harrison lathe. Joe's model is accurate and appropriate when the leadscrew is pushing the cutting tool towards the headstock. His chip load analysis is spot on. But what happens to the chip load when the tool is upside down and going away from the headstock? Common sense says chaos, chatter and premature tool wear! I can't tell because the Harrison and inserts exists in a different universe from HSS and a heavy ten South Bend(my only limited threading experience). Maybe I should learn to full form thread without the compound? Maybe experiment with finer pitch threads to begin?
How very interesting, I found the video very informative. I was playing around with this a short period of time ago, you have confirmed entirely what I have thought. Thank You again
I was always told to keep the compound square against the part being turned, but then again I was only cutting fine threads so turning the compound to 30 degrees probably wouldn't make too much difference. Also you could ensure the cutting tip was pretty square against the part being turned. Thanks Joe!
Hi Joe, I'll only use the compound in extreme situation(s), always straight in with pretty heavy cuts at the start and smaller as I go deeper... Normally it's possible to cut a 13 pitch thread in about 4 to 5 passes max, needs to be done at max possible speed though... Cheers, Pierre
Joe, just want to say I saw this when you first posted is and decided to review it again. Just as good as the first time I saw it. Also your comment about "That Lazy Machinist" Was right on. He did a excellent video also on this subject. Thank you again for all the work you do on you video. Still subscribed and watching them.
Just tried the "threading away from the headstock" in your early video. I had heard about this before but never bothered. IT...IS...SWEET! I just did straight in and thread looks great. Actually, if you *did* want to do the 29.5, 30, etc. while moving away from headstock, wouldn't you have to swing the compound to that angle on other side? Just curious - straight in works fine as fas as I am concerned...
thanks Joe, love you're videos. ive wondered about that for years. i set mine at 29ish low hp and kinda spindly! 14 1/2" southbend. not so tiny but also not a pacemaker or a monarch. thanks again
Totally agree Joe, seems like common sense to me. A better way to show it might be to view the full diameter of the threaded rod, with the tool inserted, that way you also see the helix "coming over", & down onto the tool.
A very good demonstration and I'm slightly surprised that there were no threats of burning your effigy from die hard flank cutters. From past chats on the subject there are some who think going straight in is ranked much like spitting at the Pope or going to a rock concert without ear plugs, things you should never do. I have always favoured the radial feed because of the advantages of keeping the top slide set where it is most useful, in line with the lathe axis. For threading, being able to widen the cut once full depth has been reached (to allow for too small a nose flat) has its benefits.
I really expected to find a box of challenges on the comment list this morning and got nothing but great feedback. Surprised the heck out of me. You just cant argue with the facts and graphics. Maybe I won a few people over. Who woulda thunk it?
Joe: this doc helps allergies and everything! l watch u & im a novice! watch doc late evening. One thing l remember him talking off was egg whites is allergy territory. Who would of thunk it?
Nice explanation. The rubbing action on the right hand side really helps stabilize the tool, especially on larger threads. An interesting thing to note is that on American lathes the compound 0 is usually perpendicular to the spindle axis, where Chinese lathes read 90 degrees, so you have to set them at 60.5 degrees on the compound. So if a newbe sets his Chinese lathe to 29.5 degrees, the thread is a disaster. I've seen those knife edge threads on TH-cam a few times.
Man I struggled along time with my Asian lathe before figuring out that angle difference between what I read on my lathe and what I read in books! Nobody ever seems to mention it though?
To confuse everyone a bit more I do not use the topslide for threading. I put the threading tip with a fishtail correct to the schaft and use the crosslide to feed in. No matter what the topslide angle is. After setting the gearbox to the correct pitch I always engage the threaddial at the 1 position. I normaly work in Metric and can disengage the threadnuts. Do not ask me how it works but this is the way I have learned it many years ago.
You have confirmed what I suspected all along. The reason I say this is simple. All of those who insist on an angular approach defeat their argument as soon as the begin internal threading with a boring bar. They all have their compounds set so the tool approaches the part at a 90 degree or straight in cut angle due to bar interference to the part. It kills their argument. Now, if I were to hypostulate regarding where this idea of 30 degrees evolved from, I would venture to say it comes from working with old used and worn machinery or machinery that is poorly made. I believe that with the initial reduced load on the tool as it went into the existing vee groove created by the previous pass would allow the tool to self align in accordance with the slop worn or built into the machine gradually as where a straight plunge cut would be much more forceful and tend to "vibrate" or chatter its way into the existing groove. This vibration or chatter as it bounced back and forth side to side as the machine aligned itself would tend to create a poor surface on the thread faces.
Joe, as always thanks for sharing your thrity plus years of knowledge with us negus. I Especially enjoy the why of things and most of my theorem instructors have given me a hard time about why? I Personally believe you can't understand a thing until you know the why you are doing it to begin with.
I think having a combination of why and how is the perfect mix. It not only teaches you something, it gives you something to think about and possible grow upon. Thanks for the comment.
![[MV] A leap of faith...ความเชื่อใจครั้งสุดท้าย (From "Petrichor the series")](http://i.ytimg.com/vi/U1piZH2CNXA/mqdefault.jpg)
There may be a thousand videos out there on TH-cam on "how to machine", but Joe I gotta tell ya, short of actually doing an actual apprenticeship your videos are far and away the best resource for learning the tricks of the trade. Bravo. Thanks, and looking forward to any more tips you've got to share.
That's a great compliment. Thank you.
Hi Joe, Pierre has taught me the straight in method, no issues on the Graziano.
I just ease up on the DOC the deeper you go.
Great Video as always, thanks
He's right. I plunge everything too.
Same here.
It's always good to save the worry and anxiety for the stuff that needs it. Thanks Joe.
I couldn't agree more.
I've seen videos saying both 29 and 30 degrees. Some by South bend, (old!) and one this morning saying 30 degrees also really old. I see that there is machinists on both sides of the isle. Myself I still struggle at times getting my cutters exactly perfect, so anthing that close I am perfectly happy. I'm glad that we have these great videos so I can help hone my skills. Thanks Joe for the effort, its appreciated.
Hello Joe I just wanted to say I really appreciate all of your videos I am about to Retire from a 32 year career in Law enforcement and I am thinking about getting a lathe and starting to learn metal working Something that I have always been interested in. Your videos are very educational and inspiring to me Thanks again
JPD
Thanks for the comment. I'm glad they are assisting you.
I'm 70 years old, and I always learn something from Joe P. I Never miss a JP video.!
I hope any apprentices you have, realize how fortunate they are.
Keep up the good work, it's a pleasure to watch the theory as well as the practice.
Best Regards
Mike N
Thanks Mike.
Hi Joe, when I saw the title of this video, I knew it was going to generate a huge 'mail bag' and it did not disappoint. This is what is great about the community, absorbing info from multiple sources before synthesising a work plan. Mr. Bloom would be proud of you!! Kindest regards from Bonnie Scotland. Joe.
Thanks Joe.
Hi Joe, thanks for the interesting and informative video. Another technique that I like to use, especially when picking up an existing thread, is to set the compound at 90 deg (parallel to the bed), and to advance the cross slide for the depth of cut, say for example .010", then advance the compound by half of that amount, in this example, .005". This gives a tool position change close enough to what a 29 deg compound advance would give (the correct compound advance in my example would be .0055"). The amount of cross slide advance directly compares with the fish tail gauge values, and a final light pass of .001" or .0005" without any compound advance should complete the thread form. This technique also allows precise control of the form of the thread root. With a coarse thread, for example 1" x 8 TPI, the root flat should be .0313" (P/4). This can be accomplished with advancement of the compound only. Using the 29 deg method, an overly deep root cut or special tool tip grinding would be required. Thanks again for your good work.
Thanks for watching. I always enjoyed picking up existing threads.
A few months back I experimented with this on a Sunday afternoon. I did two threads on the same piece of steel. One using the 28.5 degree and one just advancing straight in. I could not see any difference in the threads. I even examined them with a usb microscope and they look very much alike. Then some viewers told me that overseas plunge threading is normal and they had never heard of the 29.5 degree stuff. So I can certainly vouch for your facts, from my non-machnist experience. I have been threading using the plunge method since. Thanks for the great video.
I plunge everything too. I did this video to illustrate chip load and tool geometry impact on the cut. I hope the message came across. Thanks for watching.
Did the same test years ago to prove the point, and got the same results as you.
thanks Joe, like that you talk clearly and slow enough for us old folk who are hard of hearing but still want to learn. You are really a big help !
Thanks Joe. Very interesting. I always wondered about the criticality of 29.5, but never came across a demonstration of the logic involved. Very cool, thanks again...
I hope I cleared up some of the mystery.
Mr. Pieczynski; It's obvious you have a wealth of first hand experience in the craft. Thank you for your shop advice, and excellent illustrations. Being a retired lifelong machinist, I still have a love for the trade. Before I retired, I thought of myself as an accomplished machinist. Watching your videos has been really enlightening, even for an old dog. Just one thing. When setting the compound for a 60° thread, I must say I favor 29-1/2°. In my experience, especially on older equipment, I've had "scuffing" on the trailing flank, especially with carbide. (@ 30°). Tool life is shortened, due to chipping. Chips seem to be dragged past the trailing cutting edge, making a poor finish. Your equipment looks to be top-notch. You may not have this problem. Much of my experience was on old rats. Early 1940's machines, especially war production board tools. That's where I learned the trade. Mark
Joe, wondering if you could ever get around to making a full video on threading. From start to finish. Showing the full tamali of how you go about it, from putting it in the chuck to testing the finished thread for fit. Be a real treat for a beginner learning from the master how to do it the proper way.
I'm only a hobbyist, but I've always thought machining and the techniques required should be based on logic, facts, and physics. So great explanation of what's really happening Joe. Since everything is basically rubber and nothing made no matter how heavily built is ever completely rigid, plus the stack up of tolerances that allow the slides to move even on a high end brand new tool room lathe, plus the tool and machine parts flexing under cutting forces. That would tend to force the tool slightly off that 29-29.5 degree path and to the right anyway. So setting the top slide to a certain angle is still only going to be approximate to what it will actually be during a threading operation. As the thread depth deepens the cutting loads go up on the left side of the tool tip and the tool and machine parts will flex even more to the right. That angled top slide does help on my lighter lathe simply for the reasons you've pointed out. Mine just doesn't like straight in threading on larger thread depths.
Very clear with theory and practice combined. The whiteboard is great because it is so focused. Keep it up.
Any properly thinking machinist must agree with your conclusions about the compound angle - I have learnt something new. Thanks Joe.
Your teaching ability is so on point! When im having trouble fully grasping certain processes and you make a video about it, I always get it right away. Keep up the good work brother it is much appreciated 👍🏻🇺🇲
Glad to help.
Wow that's great content! Thanks for that. "29.5 deg." never made a lick of sense to me, but this is the definitive explanation why close to 30 but never over is the way to go. I never realized there was right side chip load even at 30 before, but it's clear now. I've plunge cut (0 deg) plenty of times, but 30 minus a smidge at half the chip load while still cutting the ENTIRE length of both sides is obviously the way to go. Never understood that until now. Love your channel!
Thank you very much. I enjoyed this one.
Good demonstration Joe, and the PC model makes it easy to see. I do however think some of your comments below are biased to your own experience with thread cutting for 40 years. I've been doing it half of that and always used the compound angle infeed and it's what I know, and what I'm comfortable with. Muscle memory. Why should I change? Why is having my compound always set at 29.5 a waste of my time? I like keeping my cross slide set to zero on each pass and keeping up with the depth with the compound. It's what I'm used to and it's what I'll continue to use. The proof is that it works.
Hi Adam. Thanks for checking in. You are correct. I am a big advocate of plunge cutting threads. Its my comfort zone just like your offset compound is yours. In our job shop world of "time is money" I just wouldn't support one of my guys spending too much time trying to set the compound to a precision 29.5 degrees when a quick 25 or 27 is only going to afford .0002 more of a chip load. That is a waste of time. I hope you agree. The muscle memory comment is something I will never argue. I have supervised and trained many journeymen and apprentices during my career and know first hand, 10 guys will do the job 8 different ways and get the same result. As a foreman, sometime you just have to stand back and trust someone else's hands and experience. I personally have had tough industrial machinery at my disposal for the majority of my career and have cut threads so over constrained for military applications, that plunge cutting is the only option. The compound is used for pitch diameter control once a critical root diameter is achieved by the cross slide. You are right...a good final part made in a reasonable time is truly the proof. Take care Adam. Thanks for the comment.
Something I'll add is that on my lathes I always keep the compound set at 29.5 and the tool post indicated square to the work. The lathe is most always ready to cut threads at anytime. It's when I have to use the compound for other angles is when I spend more time changing it around. At my day job machining hydraulics rods is an everyday thing, so lots of thread cutting there. Using the compound infeed easily allows you to keep up with depth if you return the cross slide to zero each pass. Keeping up with straight infeed position each time is too much for me. To each there own, I just don't want someone saying the all to familiar "your doing it wrong" just because there's more then one way to get the job done.
Hi Adam. I can understand everything you said. I too usually have my tool post indicated to zero, and usually have at least 1 tool holder where the vertical tool registration surface is also ground to zero. Thats my thread block. Your environment is perfect for your setup and technique. My latest video was more to address everyone's belief that there is no right side load with the 29 degree method. I think I successfully proved that is an incorrect statement. I am more than open to new methods and ways. Its what helps us all grow and learn. I would be the last person to ever say, you're doing it wrong' just because you are not doing it my way. We all have our techniques. Stick with what works and gets the job done, but keep an open mind for the next best thing. Regards JP
Joe Pieczynski. Abomb's Monarch, and mine also, has a return lock on the crossfeed dial that's designed for single point threading. It allows you to set the crossfeed at the major diameter of the thread, then back out of the cut, and return the carriage to start the next pass with a positive stop on the crossfeed, and dial in the depth of the next cut on the compound. The exact depth of the cut can be determined with a little trig, or read direct from an indicator.
BTW, my 1946 Monarch CW 18x54 has 29 1/2 degrees plainly marked on the compound protractor.
peace-out..Tc
Im 60 and got so scared of machines in HS i couldnt become a machinist. too much too fast. But I recently had a stroke and the logical part of my brain is starting to learn again. Boy I wish my machine shop teacher was as good as you. with a damaged brain I understand more than he taught. Thanks Joe
Thanks for the support.
Mr Joe, u explain so my 4 year old daughter can understand. Some ppl get lost quick with extra words. Btw U are the only Yutube Lathe I watch. Do some CNC Programming . Thank u sir.
Joe, well played. I just got to watch this one (3 years late!), and it is probably the best representation of tool movement and cutter engagement I have seen on the single point threading subject. The computer assisted tool trajectory image made the video. My background is in engineering, and this is spot on. This should be required content for any apprentice learning to single point. This has other applications as well, as tool trajectory is always a consideration in any machining application although not always as critical as in threading. Again, outstanding rendition and simulation.
I enjoyed seeing your computer modeling skills. As a T&D apprentice this theory was explained to me by an old French t&d maker. He was a master. He demonstrated cutting (moderate diameter) threads to size in a total of 3-4 cuts! Scared the crap out of me. He could do it every time. All HSS in those days. Time was money. Wouldn't tolerate scrapping 5 thou or so per pass. Rip Emile.
Thanks Michael. My modeling skills are solid on Pro-E. I enjoy it. I've go some crazy model in the files. Take a look at my 'Modeling a gage perfect thread" video. If you think about tool contact, your first thread cut can be very deep because the tool contact is so small. No reason to grow old running a thread.
I am new to all of this and as yet have not tried to cut threads because I could not picture the reason for the 29.5 angle. This video cleared up that for me. Thank you so very much. Oh, I am trying to teach my self and really have no one to ask about things like this. Thanks again.
Feel free to ask a question. A fresh comment will have a better chance at a reply. Good luck.
Joe, i would like to start by thanking you for so much amazing info, you have helped me in a huge way! Second, if i could split my insert it could still be done, if your compound is set at 30 degrees because of the fact that it is a helical movement, you do not contact the right side of the tool. Your pc model is only good if the tool is not moving to the left or right. If the tool is stationary and the part is rotating then yes! That would be the effects of cutting. But you are not plunging! You are effectively scraping the surface of the part as it rotates and the tool moves from one side to the other. If the right side(using your model that is threading from right to left) of the tool is cutting then i would be forced to say that your tool is not moving at the right speed, i.e to slow. I can't wait to hear back from you. Thank you again so much!
Greetings. I have to respectfully disagree with your conclusion. Any advancement of the tool towards center, compound or cross slide, plunges the tip of the tool into the part. It is impossible to advance a tool into any material and not translate the area of the tip of the tool as the cut profile. If you were to split a threading tool and set your compound to 30 degrees, your incremental depth movements would have to be microscopic and you would have to make 100 passes or one side of your thread profile would be serrated. The computer model proves this without a doubt. Doing that is not like back turning a 30 degree taper. Totally different.
I am rather new to machining especially compared to your career in machining so i am rather stumped on this, so if you are strictly talking about the plunge of the tool into the part, at what point of threading do you ever plunge the tool in? That wouldn't leave you with a thread, that would leave a groove.
@@zachjohnson3261 i see why you are confused, but it's difficult to explain. the way you talk, you are thinking along the lines of, even when you're not threading, your still threading, because normal turning is technically still threading, because you're always cutting a spiral, it's just that a actual thread is just really coarse turning, say a hundred thousandths per rev instead of three, but where threading differs from turning is that 1. you are leaving material on the o.d.,the material that forms the thread, and 2. the tool is clocked to the part, and is "retracing it's footprints", it does not move away from the left side, if it did, the root of the thread would keep getting wider with every pass, the left side of the tool is locked on a tangent axis to the left side. think of it this way, when you do you'r first pass, the whole tip of the tool is cutting, on both sides, the second pass is exactly the same as the first, the tip of the tool is still cutting on both sides, the only difference is that on the second pass, you're using the right side of the tool to make the cut wider.
This is correct, same as if you are reducing the diameter of a shaft with a conventional slide feed cut. Are you cutting off both edges of the cutter then? No, not really. The left side of the cutter is removing the material, the front tip of the cutter is behind the material that was already lifted by the leading edge of the cutter. Equally if you are using a parting tool to plunge 90 degrees into a part, is the side of the cutter cutting? again, no not really, it is behind the leading edge of the tool that has already lifted the material.
The main point of running at a 29.5 degree is to keep the tool pressure holding the carriage lash tight to the lead screw, while reducing tool pressure at the bit. Look at the difference in the swarf coming off a straight threading cut vs one where you are feeding the compound cutting off "one side", huge difference.
You are absolutely right .setting the compound at 30 degrees minimizes the load on the tool and the lathe with better finish.
I love this content. I spent a semester at WA state in a machine work class and was always told 29.5. A decade later I’m still doing hobby job theads like barrels with that same teaching with great success. Keep up the great content!
Great video Joe. Sandvik also has a good video on all the different types of threading. Thanks again.
Thank you, now I understand why this number isn’t critical. Makes perfect sense.
Hi Joe;
This very subject has probably started many arguments over the years. I'm saying that as a humorous aside, not to lessen the info in your video, which I enjoyed. I always enjoy being right. :)
I do agree with you, no matter the angle, both sides of the tool cut, and I was convinced of that before your excellent computer demo. Well done on that!
The 30 deg angle does help small or old machines, and that is probably where the practice originates. Like one comment mentioned, it likely made a difference to old forged tools, as well as old machines even when they were new, considering babbitt bearings and less than perfect gibs. Back in the steam power days.
One thing the 30 deg angle offers is to effectively increase the resolution of the infeed on the compound if you use a little trig to figure it out. Other than that, meh, plunge it and cut that thread.
Thanks for another well presented vid!
Thank you Joe, i never really understood this before. Understanding the the tip as a form tool was the ah ha moment! As was the fact that you can form a perfectly good thread with a straight plunge, so it follows if 0 degs works and 30 deg works 29 or 29.5 deg should work with no problem , clearly it does.
Hi Joe, English born and engineered here, and I like your analysis and explanation, but to be fair, in our neck of the woods...we were never taught that using compound projection toolpath totally eliminated rear side cutting (or rubbing).
Quite the opposite in fact. We were always taught that there would be material contact via depth of cut, however, this was always spoken as "good practice". The reason being that the root form is executed more securely if the tool is cutting around the tip or root of the thread, be it a flat form or radii form. To suggest that "snugging" the root form is a stronger and perfectly defined process. However we we also taught that upon forming the "root", minimal contact on the trailing edge was also paramount...
I kinda get what you are 'myth busting' about and agree, but as I say... My educators never claimed that no tool contact was made on the trailing edge...rather just to keep it to the root form for rigity in cut etc...
Thanks Joe, first time single point thread cutting, this coming weekend, can't even begin to do that without checking you out.
Thanks as always Sir, you've more than helped and inspired as always
Thank you. Be sure to consider this method if your machine will allow it. th-cam.com/video/Z-dqOi_z5bk/w-d-xo.html
@@joepie221 I checked that out a while ago, that fuelled my interest in single point threaded lol
Thanks for another great video. One thing I learned from watching Bruce Wittham is that machinists in a lot of countries outside the US plunge cut threads using the cross slide only with no problems. I'm going to stick with 29.5º because that what I've always done and the chip load is low. Chris
Unless there is a specific root dimension given, I plunge every thread I cut.
It's not a US versus the rest of the world issue, if memory serves the really early South bend books showed going straight in. Having said that, go with what works for you or you are comfortable with, that way you will make less errors, even if it is not necessarily the best way.
Hi Joe, good video.Took me back to the mid 70's when I was training in UK. I was taught to do Metric and Whitworth (had half nut drop out during finishing cut on a 1" Whitworth, wasn't good, still got a scar . I didn't know any better back then ) 'We' were taught to use anything from 10 to 27.5 degrees or just plunge cut forsmaller dia. 55 degree Whitworth threads. T he difference on 'shadow graph' was noticeable, and looked like north face of the Eiger when magnified 500 times. (Surprisingly, Honda motorcycles used Whitworth threads back then on some components, I used to measure 'everything and anything' to practice) You mentioned tool was likely to rub rather than cut, often it does. even with industrial machines which are way bigger plus more rigid. That was the reasoning behind using smaller angles, get tool loading reduced but not removed. It was obvious both sides of tool were cutting even at 27.5 deg. Only subscribed last week, jobbing machine shop does more interesting things than factory machining.
Thank you George Carlson!!! I apparently have a Chinese (ENCO, should have guessed it) lathe. As per your post, I set my compound slide at 60* and VIOLA!! Perfect cut! Since the graduation tag only reads to 45* in each direction, I rotated my slide to 30* and scribed a mark at "0" then rotated it on around until 30* aligned with my scribed mark. Works like a dream. Out of all the thread cutting videos I have watched, I don't remember anyone mentioning the diff in compound slide markings between different manufacturers. Thanks again!
George Carlson was a comedic genius.
Old topic but YT recommended it so I researched it. I usually just go straight in as I can't be bothered to move my top slide off its carefully set to parallel position. Years ago I did a series of tests cutting a 1.5mm pitch thread in 303 stainless going straight in and with offset top slide using the same full form insert. Looking at the results
under a microscope I could not tell which was which as they looked identical.
Having said that, today I cut several 1 5/16" by 9TPI threads in Aluminium on an unpowered Myford, don't ask, and set the top slide over just to give my left arm a chance of being able to lift a beer bottle afterwards.
Hello Master Joe,
I only have a small lathe and not all these magnificent machines you can use. But your ideas, principles and methods are great and I adapt them to my small shop.
You explain everything very well. Thanks a LOT.
Stay Healthy,
Pierre
I truly love your videos Mr. Pie.
You're good nature and humor, the consistency of your explanations and demonstrations, and thoroughness of information is what really makes them a pleasure to watch. It's almost as good as being in shop class with the guys. I particularly enjoy your old school utilization of your dry erase board and filming your computer screen. If it ain't broke, don't fix it, right?
With that said, regarding threading, I have very little experience with it and have a few questions.
If your 60° HSS thread-form tool is set perpendicular to the workpiece, the cutting plane is ran parallel to the threads being cut, the cut is typically began from either a relief channel or from outside the part and ran into the cut itself, what does the angle of the Compound have to do with anything other than approximate measurements to get in the ballpark of your desired Pitch Diameter?
Also, what methods do you use and recommend to set your tool height and Perpendicular to your workpiece?
Joe, thanks for the explanation. After watching your inverted tool video method of treading, I go strait in. If you take small bites, it works for me and I can use the cross slide DRO to get the required depth of cut.
Excellent. Makes it easy doesn't it.
Think that seems to prove once and for all a thread tool is a form tool and ALWAYS cuts on both sides.
Setting the compound to 29 degrees etc only serves to REDUCE tool load on the right side of the tool ( when cutting towards the chuck )
Got it ! Thanks Joe
I’m in Britain and have a small 4.5” smart+brown model A lathe iv cut various 55degree whitworth threads ( native to this machine ) just for fun mainly and have previously just cut them , filed them till a nut fits.
Having watched your various threading videos I now plan to dial in my depth of cut with the cross slide at the extremity of the thread forming a “relief groove” then verify the pitch diameter with wires back out the 27degree compound then cut the thread using the compound only to hit the exact pitch diameter 1st time 🤞🏻
Great videos excellent content, well explained 👍🏻
Side note I think the inverted threading looks superb why doesn’t everyone do this ??
Unfortunately iv a screw on chuck and won’t be able to try this 🙈
Love your videos. Not just "do this" but why you should do this. Understanding makes all the difference.
Thanks Joe. I had been worried that if I wasn’t exactly 29 1/2 degrees, which on Asian machines may not be close, my thread would suffer. Your explanation takes away the anxiety. Thanks again, JB San Diego
I have abstract thought not all people do but I could see you computer program in my mind some time ago.
I also looked at the chip the tool produced and you can see it is cutting on both sides the trailing side the least, there is no way it cant.
Most if not all of the time I dive straight in anyway.
I set the top slide/compound parallel with the cross slide.
I back out and in with the cross slide and cut to depth with the compound slide.
Plus as you do I do all of it going out not in.
Works for me.LOL
Thanks for the great non rehash BS videos we all see here way too often.
Worth
Thanks Worth. I'm sure I'll double someone else's work eventually, but it will be by accident.
That is the first decent explanation of the suggested angles that I have seen. Finally makes sense to this hobbiest. Thanks
I have had the occasion to cut a square thread on a restoration. What compound angle makes sense. Zero or minus 1/2 degree?
I would have to believe the tool should be ground square or less, and the feed angle should be zero.
@@joepie221 thanks
Another good video Cap'n
Although this was directed at Your Imperial Thread Cutting audience, we reckon it would be most applicable to our Metric threads as well.
Putting the demo on CAD clearly shows the cutting angles perfectly
Thanks again for showing and sharing
aRM
Thanks, the CAD does really help.
You say Imperial threads , but this doesn't work for the British Whitworth threads @ 55 degrees.
I recently threaded with slightly less than 30 deg., but decided to try a smaller angle-- 15 deg. And surprisingly the cuts went smoother (reduced chatter) with the same light pass techniques. Sometimes, maybe it is many facets of the processes involved: tool, material, machine.. . and so on...
Thanks Joe for another thought provoking discourse !
My thoughts have always been that the area of metal which you identify as being removed by the right side of the tool is in fact removed by the left side, as the helix of the thread means that it is presented to the left face of the tool before it sees the right side, or am I wrong ?
I can recall my college days, back in 70’s, when we did some investigations into cutting forces in machining operations.
All machining is a tearing process, where the force generated at the tool cutting edge has to exceed the ultimate tensile strength of the material being cut, and it follows that the greater the length of cutting edge, the more load there is on the tool.
To minimise the loads on the form tool, which is often quite a frail device, it made sense to only cut on one face, so that the flow of the chip was cleanly away from the tool cutting edge, and this was clearly demonstrated by less tool deflection and lowest power consumption.
Plunging the tool into the work perpendicularly to its axis means that you are cutting on both faces and the two streams of chip come together and are compressed as they try to escape, which further increases the load on the tool tip beyond the expectation of that due to the doubling of the shear area.
Furthermore, with a flat topped form tool, when you take into account the thread helix, the left side of the tool has some degree of positive top rake, whilst the right side of the tool has an equal amount of negative rake. This might be problematic when machining some materials . . . .
It might give you a wry smile when I tell you that the machine which we carried out the tests on was a brand new Colchester Triumph 2000, fitted with a 3phase watt meter for measuring electrical power consumption and strain gauges on the tool holder, to measure the deflection of the tool !
Load on the tool eventually translates into wear at the cutting edge, as some exponential function, so any reduction keeps the tool sharp for longer and, on a batch run, makes for more quality threads, before a tip replacement is required.
Now retired, my little 5 x 20 workshop lathe ( probably even older than me ! ) isn’t capable of dealing with a plunge cut, so I’m not too proud to set the compound slide over.
To sum up, plunge cutting is fine, if your machine and tool set up are strong enough to take it, but on a production run, the economics of higher power consumption and increased tool failure might not yield the expected profits.
As my college lecturer, himself a retired production engineer, was fond of reminding us “Gentlemen, our job is to make as much swarf, as fast as possible, because the customer only buys what’s left !”
Apologies for this rambling dissertation !
Kind regards,
Steve.
Thanks for these paragraphs. They’re easy to understand and flow very well for me
Done a lot of female, acme, double leed, left hand threads for limit torque operators in motorised valves. These were made of aluminized bronze. This stuff is hard and tough. You want to talk about wanting to chatter. The bores were not that big, and the nuts were fairly long, so good boring bar rigidity was never there. Typically, a general purpose acme at 28 degrees, so 14 on the compound. This stuff actually chattered worse on light cuts. Less tool pressure more harmonics, I suppose. So, I just started setting the compound at 90 and plunging straight back. Most were 2 sets of 2 at 4 threads per inch. So, slipping the nut was the norm. Anyway, with the compound at zero, I could fudge the tool forward and back, turn the lathe chuck very slowly by hand while engaged, and remove chatter marks when I was to depth. Engineering wanted a looser thread fit, so tolerance was not a problem as the minimum thread crest was not exceeded. Wow, that was 25 years ago.
Thanks for taking the time to teach guys like me your skills. You explain clearly and I am the better for it. Best wishes from Ireland.
Thank you. Regards from Austin Texas.
Hey Joe
Where you going with that……….I,ll stop that
I was a production lathe operator back in the sixties and seventies.The setter would set up the machines,which were often capstan lathes or centre lathes and screw cutting was an everyday event.
You really were spot on with the nerves when screw cutting but we just learned the tecnique and got on with it.
The method you described here would have saved my premature ageing but as i was watching i wondered if you were brought up old school and used the old method of screw cutting first or did you develop this because of the nervous shake that would develop as you neared the under cut and had to stop the machine, remove the tool …..no i cant go on
Keep up the good work, respect.
Great video, Joe. Thanks. I have used lathes for a couple of decades now but just as a self taught (trial and error) machinist, and I used that term very loosely. Mostly facing, turning and grooving. I am now needing to learn thread cutting. Following these instructions, the outcome of my efforts is a thread that more resembles a "buttress" thread. I have the correct TPI and have all but mastered the half-nut engagement (thanks for that video, as well) but with using the cross slide only for plunging and retraction and the compound set at 29-30 degrees, all my practice pieces come out with a very lopsided thread. The leading (cutting) edge actually appears to be 10-15 degrees and the trailing side appears to be about 35-50 degrees. I am using a 60* thread cutting insert and am cutting a 7/8"-9 external thread on PVC solid bar stock. I have also tried it with aluminum bar with same results. A nut will easily thread onto it but it just doesn't look good/correct. I don't know what I'm missing here.
Try just plunging straight in
Great video Joe let's hope it makes it clear for a lot of people.
Personally my own experience when I first started in the trade 60 years ago I used to plunge straight in and trash the tools. (HSS on a manual engine lathe) breaking the very tip.
Back then I never understand why.
If you plunge straight in you have equal chip load on both sides with a tendency of the chips loading up and destroying the very small tip of your tool.
29 1/2°, I've used ever since an old timer explained why.
Most of the cut is on the left side most of the chip curl away clean while the right side of the tool just barely skins but just enough to make it look good and clean and a lot easier on the tool.
Like this video proves, both sides still cut, and the tip is always working. Carbide like to be buried, but HSS may be different depending on the setup.
Thanks Joe. Love your videos,
I checked this out using my own cad to hammer the concept into my brain. More than 30 degrees results in a stair step, less than 30 and the right side of the thread is either burnished or cut but thread is perfect just the same.
More than 30 on the compound never ends well.
Just subscribed. Of coarse I started watching your videos in reverse order, but I will catch up. Well presented and to the point. Thanks Ed K. Cleve. Oh.
Thanks Ed. Welcome aboard
Like many I started with a SB 10K back in the late 60s and stayed with the way I was taught until you came along. I have a 3 horse 14-40 chinese machine I have had for 20 years. It does just fine with straight in threading, just do the scratch pass at final to clean up. do a lot of rifle barrels, threading, away from the shoulder is great, thanks and keep the info coming!
All this time I thought it was a bad setting on the compound, guess there must be another reason why it is raining frogs in my shop. Thanks for another excellent video.
Thats funny. Good comment. I hope this took some mystery out of the setting.
Have to admit I didn't know what the 29-1/2 degree was for even tho I know that angle and I simply used the cross slide knob for threading. It'll be fun to see how my next threads turn out. Thanks Joe!
Dang Joe, thanks for the very informative video. Actually, the first of yours that I watched concerned threading with the toll upside down, spindle in reverse and cutting away from the head stock. I had to try it for myself, it sold me. Then I watched this video. OK....I hit the subscribe button. I like how you think and work.
Thank you Mr Joe for sharing your wealth of information and knowledge. I’m new to the machining game and your channel is my #1 source of education. I reset my brain to the plunge thread cutting after seeing your videos and trying for myself I realized how much better results I was getting compared to the compound feeding at 29. I wish I could try the reverse tool technique but I have an old ( 1944) south bend 9A with a threaded chuck. Thumbs way up to your channel and content!!
Don't completely abandon the compound approach since it does serve a purpose. On smaller diameter parts, the lower load can really help. Thanks for your positive support.
@@joepie221 copy that! Thanks!
I never thought that 29.5 degrees was a solid angle but it was simply to lower tool pressure. I was taught to finish with a straight depth cut. Depending on material type maybe tenths or a couple of thousands.
I Dig your videos, by the way. I've been machining for 30+ years off and on and sometimes I feel like I'm a boot camp in the Navy when I hear something new!
Thanks for the video Joe - very informative; however in addition, I'd like to see you do something similar explaining some of the calculations, terminology, tables, etc. that deal with how deep to advance your compound to achieve the proper thread depth, what is meant by "double depth of thread", thread types, what the numbers on the fish tale mean and how to they relate to compound depth, etc. Basically I'm asking for "basic" info that you pros have learned through experience and/or formal & informal education that us weekend hobbyist haven't had the benefit of. Also, the dial on my lathe's compound must be different from most machines. To set mine to 30 degrees I have to set the dial at 60, so to achieve 29.5 would I set to 59.5 or 60.5. :-) Thanks again!
28 people who downvoted this video should not be allowed anywhere near the lathe (or any other machine). Also, they should post their names here so those who read comments don't make a mistake of hiring them for any machine work, either.
You are pushing your luck Ian.
Thank you. I'm just about finished seeing up a minilathe to start learning while refurbing the Sheldon. My first project is facing, turning and drilling only but the second one I want to try threading. I watched the video to get exactly the information you presented. I saw @Abom79 commented a few years ago and I have a lot of respect for the work he does but this is far more apropos for a beginner with a light, Chinese minilathe than the rigidity of the big machines he's running. If I run my first try, it won't be because I didn't do this correctly, thanks to you. :-)
Thanks Joe....sure answered a lot of questions that have had me curious on threading.....
Hey Chuck. The whole 29 degree thing is always taught, but never explained. I hope this cleared things up a bit. Close enough is good enough.
You're right on sir. good demo. I agree with Barry on setting up short of 30 degrees i.e. 29, 29.5 or even 28. Just don't go past 30.Thanks Joe
Hi Chuck. Its all a matter of machine rigidity. I rarely use my compound for threading. Thanks for watching.
Interesting video. I agree totally that as long as you don't exceed 30 you will get a good thread. One point someone once made was that if your last few passes are done by plunging with the cross slide, then any discrepancy caused by compound alignment becomes irrelevant, as the tool is acting as a form tool.
One question - when using the reverse threading technique that you have shown, should the compound be set at the opposite angle to when you are threading conventionally? Eg. 29 degrees the other way?
I plunge everything. 100% of the time. I would suspect the compound setting should be the same for the inverted tool. One side would still be cutting, it would just be the trailing edge.
Excellent Video, I haven't bothered to set my compound at 29.5 for years, With modern tooling (Inserts) I just plunge straight in after ensuring that my tool is set perpendicular to the axis. I taught my students the same thing. THe only time I use the compound is when I am using high speed hand-ground tooling and then only if I am on the first cuts, when I get in deep and am neat finish size I do the last few thou's with a plunge cut, it kinda evens up the finish. Excellent Video dems of what I was taught years ago.
I too plunge all my threads.
Hi Joe, Thanks for the excellent demonstration of a subject not well understood. I've cut many threads at 30 degree angle and straight in and both work well. However, there's one situation where a 29/30 degree angle produces superior threads than straight in. Lets say you're cutting a 1.00-8 thread in 304 SS, 4140, aluminum bronze, or other tough material. In that case an 8/10 degree positive side rake produces a smoother cut with less chatter than feeding straight in. Keep 'em coming.
That aluminum bronze is fussy material. Not hard to work with, but don't take small cuts or it just shines up and laughs at ya.
Right as rain Joe. Interesting how Aluminum and Bronze, both relatively soft, produce such a tough alloy when combined.
Fantastic bearing material.
yes Joe I have done it both ways on smaller threads my biggest problem is I get a lot of chatter and my Trent but I will keep trying
Another great job thanks
Have you tried my inverted tool technique yet?
Sorry Joe I have a spin on on Chuck
Very clearly explained Sir. I have a small EW Stringer lathe that I am about to start cutting threads with.
I could not understand the reason behind having the compound set at an angle.
I do now.
Thank you.
Thanks. I enjoyed doing this one. I
Great Info! I always use 29 degrees and have often wondered what the difference is between 29 and 30.....I always grind hi speed tools and was taught that the angle greatly minimizes the stress on the tool, part, and machine.. Mike in Louisiana
Sort of a beginner machinist here - wow! Thanks for the THOROUGH explanation.
I have several threading videos on my channel. As a new starter, you may find value in each one. Good luck.
Great example, Joe! Thanks for sharing. Love the channel; I learn something every video.
Great to hear. Thanks.
The reason you should cut at 29 is so you don't get a chip from each side feeding (and smashing) into each other on top of your tool
especially on larger threads I can cut way more per pass this way and tools aren't breaking
the reason we go 29 instead of 30 is to make sure to drag the right and keep nice profile and finish
the last .005 I do straight in a couple fine passes
heavy chips do not like to be fed straight in to each other especially on ss and any steels or harder metals
brass you can feed straight if u want
Thats all i have to say about that
Hi Joe Just want to say how much I enjoy your video's, very useful and informative.
Regards
Andy (from across the pond!)
Thank you. I try to address the areas that show they need addressing.
Joe that digital model makes things so much more clear and answered a lot of questions in my old fart mind. Thanks for all the effort you put into your videos. I sure wish you would consider teaching some classes, hint hint.
As a backyard hobby machinist, I watch Joe's tips religiously and learn from every one of them. This video ignores a giant, checkered yellow, elephant in the room. Namely Joe's religion of threading in reverse and away from the headstock. I just made a custom BXA holder so I could get a left hand threading tool high enough to get the tip on center and cut a few threads on a new to me and in new condition 13x40 Harrison lathe. Joe's model is accurate and appropriate when the leadscrew is pushing the cutting tool towards the headstock. His chip load analysis is spot on. But what happens to the chip load when the tool is upside down and going away from the headstock? Common sense says chaos, chatter and premature tool wear! I can't tell because the Harrison and inserts exists in a different universe from HSS and a heavy ten South Bend(my only limited threading experience). Maybe I should learn to full form thread without the compound? Maybe experiment with finer pitch threads to begin?
How very interesting, I found the video very informative. I was playing around with this a short period of time ago, you have confirmed entirely what I have thought. Thank You again
Its all smoke and mirrors. I hope this clears things up a bit. Proper tool alignment is still important, but the compound....not so much.
Great explanation...always heard 29 1/2 but know one has ever explained the tool load as well as you do.
I was always told to keep the compound square against the part being turned, but then again I was only cutting fine threads so turning the compound to 30 degrees probably wouldn't make too much difference. Also you could ensure the cutting tip was pretty square against the part being turned. Thanks Joe!
Hi Joe,
I'll only use the compound in extreme situation(s), always straight in with pretty heavy cuts at the start and smaller as I go deeper...
Normally it's possible to cut a 13 pitch thread in about 4 to 5 passes max, needs to be done at max possible speed though...
Cheers, Pierre
Absolutely spot on. I agree 100%. I never use the compound either. I did this video to release some of the 29 degree mystery.
You are nothing short of a genius Joe. I have massive respect for you and your knowledge. I have really learnt a lot from your videos. Thank you
Thank you very much.
@@joepie221 you are most welcome. I am a recently qualified toolmaker and I'm also into gunsmithing. Really appreciate your videos
Joe, just want to say I saw this when you first posted is and decided to review it again. Just as good as the first time I saw it. Also your comment about "That Lazy Machinist" Was right on. He did a excellent video also on this subject. Thank you again for all the work you do on you video. Still subscribed and watching them.
Still good to have you on board. Happy New Year.
great job professor P. I know just enough to dangerous, now I feel less dangerous. thankyou good sir
Now you have more room to learn something to make you dangerous again. Thanks for watching.
Just tried the "threading away from the headstock" in your early video. I had heard about this before but never bothered. IT...IS...SWEET! I just did straight in and thread looks great. Actually, if you *did* want to do the 29.5, 30, etc. while moving away from headstock, wouldn't you have to swing the compound to that angle on other side? Just curious - straight in works fine as fas as I am concerned...
watching far a second time and always great Joe......you are the Man...cheers from Florida...Paul
Thanks Paul.
thanks Joe, love you're videos. ive wondered about that for years. i set mine at 29ish low hp and kinda spindly! 14 1/2" southbend. not so tiny but also not a pacemaker or a monarch. thanks again
The compound feed does benefit less rigid machines. The angle is just not critical at all.
Totally agree Joe, seems like common sense to me. A better way to show it might be to view the full diameter of the threaded rod, with the tool inserted, that way you also see the helix "coming over", & down onto the tool.
Great illustration, Joe Pie!
Thanks for sharing
The software made the demonstration very easy to prove. Thanks for watching neighbor.
A very good demonstration and I'm slightly surprised that there were no threats of burning your effigy from die hard flank cutters. From past chats on the subject there are some who think going straight in is ranked much like spitting at the Pope or going to a rock concert without ear plugs, things you should never do.
I have always favoured the radial feed because of the advantages of keeping the top slide set where it is most useful, in line with the lathe axis. For threading, being able to widen the cut once full depth has been reached (to allow for too small a nose flat) has its benefits.
I really expected to find a box of challenges on the comment list this morning and got nothing but great feedback. Surprised the heck out of me. You just cant argue with the facts and graphics. Maybe I won a few people over. Who woulda thunk it?
There is no wrong way until you realize it's wrong. Until then its right.
I believe that is called learning.
Joe: this doc helps allergies and everything! l watch u & im a novice! watch doc late evening. One thing l remember him talking off was egg whites is allergy territory. Who would of thunk it?
Thanks for sharing the knowledge. I have to learn and relearn what is forgotten. These videos help a lot.
Nice explanation. The rubbing action on the right hand side really helps stabilize the tool, especially on larger threads. An interesting thing to note is that on American lathes the compound 0 is usually perpendicular to the spindle axis, where Chinese lathes read 90 degrees, so you have to set them at 60.5 degrees on the compound. So if a newbe sets his Chinese lathe to 29.5 degrees, the thread is a disaster. I've seen those knife edge threads on TH-cam a few times.
Those threads work great as wood inserts
Man I struggled along time with my Asian lathe before figuring out that angle difference between what I read on my lathe and what I read in books! Nobody ever seems to mention it though?
Excellant Joe!! That's the way I've always cut mine and have had no problems.
To confuse everyone a bit more I do not use the topslide for threading. I put the threading tip with a fishtail correct to the schaft and use the crosslide to feed in. No matter what the topslide angle is. After setting the gearbox to the correct pitch I always engage the threaddial at the 1 position. I normaly work in Metric and can disengage the threadnuts.
Do not ask me how it works but this is the way I have learned it many years ago.
What grade of HSS
You have confirmed what I suspected all along. The reason I say this is simple. All of those who insist on an angular approach defeat their argument as soon as the begin internal threading with a boring bar. They all have their compounds set so the tool approaches the part at a 90 degree or straight in cut angle due to bar interference to the part. It kills their argument.
Now, if I were to hypostulate regarding where this idea of 30 degrees evolved from, I would venture to say it comes from working with old used and worn machinery or machinery that is poorly made. I believe that with the initial reduced load on the tool as it went into the existing vee groove created by the previous pass would allow the tool to self align in accordance with the slop worn or built into the machine gradually as where a straight plunge cut would be much more forceful and tend to "vibrate" or chatter its way into the existing groove. This vibration or chatter as it bounced back and forth side to side as the machine aligned itself would tend to create a poor surface on the thread faces.
Best machining instruction resource on the internet, IMO. Thanks!
Many thanks.
Joe, as always thanks for sharing your thrity plus years of knowledge with us negus. I Especially enjoy the why of things and most of my theorem instructors have given me a hard time about why? I Personally believe you can't understand a thing until you know the why you are doing it to begin with.
I think having a combination of why and how is the perfect mix. It not only teaches you something, it gives you something to think about and possible grow upon. Thanks for the comment.