Turning precision diameters
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- เผยแพร่เมื่อ 11 ต.ค. 2024
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I didn’t think you sounded arrogant - you sounded honest. We all make mistakes! The important part is to learn from them.
It sounded like he'd been watching me at my lathe. Except I don't use HSS, was too lazy to learn to grind them properly.
@@outputcoupler7819 indeed, me too, in my experience, nudging up a little at a time ends up with two or three rounds of burnishing, until on the last go, the pressure gets high enough for a proper cut to occur, and it ends up way to deep😀
Even better to learn from the mistakes of others :)
my boss turns precision fits this way since 30 years...not that successful i might add, also it takes him forever ;)
good video SG!
when are you going to put out another video? we miss ya.
Gotta agree. Sneaking up on a size is not only unreliable but wasteful in time. If a canny supervisor sees you making dust-like chips too often and you persist after he talks to you about it, it might lead to employment opportunities elsewhere. Stefan learned the use of balanced finished cuts in Germany in his apprenticeship. I learned it in Washington State in mine early '60's from an old machinist who learned his trade durinf the Depression in an Alabama railroad shop. A Korean sales rep who told me he learned the same technique when he was on the tools.
One thing I note on most machining videos in many TH-cam videos featuring lathe work is the narrative often blurs distinctions between diameter reduction and depth of cut. In direct reading dials where the micrometer collar registers slide movement, dialing in 1 mm on the slide takes 2 mm off the diameter. In diameter reading cross slide dials, dialing in 1 mm reduces the work diameter 1 mm. To add confusion the compound slide is usually direct reading.
In discussing these matters, "depth of cut" (DOC) should represent radial movement of the cross slide. Manufacturers base their insert reccommened speed, feed, and DOC data on radial, not diametral tool movement. HP and stock removal calculation formulae, speed and feed slide rules, nomographs etc are based on radial depth of cut. So if a presenter is to minimize confusion, he should clearly state "I'm taking 6 mm off the diameter" not "taking a 6 mm cut." A 6 mm cut to an old school machinist running a lathe means 12 mm off the diameter. A 12 mm diameter reduction cut would challenge the power and rigidity of most home and small commercial shop lathes. Are you hearing me out there Adam? Tom? Robin?
As it happens 0.5 mm is pretty close to 0.020", my default balanced cut for semi-finish and finish cuts for most work. Most any carbide insert performs well at this DOC at reccommened speeds and feeds and is sufficient to penetrate below the work hardened film the previous cut.
None of this is writ in stone. Materials, tool, machine condition, deflection, temperature, surface finish, etc all affect the optimum semi-finish and finish stock. What works for cast aluminum may not work for inconel. Be observant and flexible.
I am a simple man, I see a Stefan Gotteswinter video; I smash the like button.
To be fair, he's never made a video I didn't like, so why run the risk of forgetting to click... ;-)
You did not sound arrogant Stefan. This is an excellent technique and I'm sure your demonstration helped many people.
"I am a trained professional on a closed track." :-D
LOL... almost as good as “this old bunker”. 😂🤣😂 Love that German humor.
Now you've pointed this out, it comes to mind that Abom does this everytime. Great to see the rational behind it explained👍👍
Not "everytime". He often uses a lathe file and/or abrasive cloth to get to a desired diameter. There is none of that here.
MrShobar, it seems like abom does that when he wants a more polished finish on the part. I have seen abom on many occasions, split the difference of cut on the last two cuts and it comes out perfect.
2LeftThumbs yes also uses DTI
Some materials just don’t want to finish nicely so yes he comes in a little over size (still balanced cuts) and polishes the last part in.
I’ve been doing this for over 50 years guys, and I’ll tell you something. It doesn’t matter how you get there, as long as you do.
Stefan, this type of short educational video is pure gold for us hobby machinists. Please do more.
I'm a self taught lathe user, I always used to try and sneak up on a precision dimension with tiny cuts and guess what? I often over shot! I will be using your balanced cut method from now on.
Plus, I have just bought a very tidy Emco Super 11, so I must learn to use it properly.
Many thanks, Paul in NZ
It’s obvious you’re always striving for perfection. Your, English, narration, and of course your work. Hell man I’d like to see your lawn. Thanks for bringing us along.
Especially those little tricks,are what really helped me out a lot through my time as a hobbyist.
An honest thank you Stefan!
Please keep it up!!
No apology required Stefan. I think you fan-base appreciate the lengths you go to to make these videos and your tutorials are always warmly received. I fall into the category of 'sneaking-up on dimensions but will adopt this method from now on. Cheers!
You can be as arrogant as you want. When Stefan Gotteswinter talks about precision, I shut up and listen. 😁
Good stuff Stefan! You didn't sound arrogant but I like the intermission idea, I may use that.
ATB, Robin
We were using this technique in my night school machining classes. I just didn't trust it on my Chinesium lathe though, and was using the "sneak up" method as you described. Recently returned to using this method and it has proven better results. For what it's worth, no one here would ever accuse you of being arrogant, you are one of the most self-understated people I have seen on TH-cam. And, you truly do know what you're doing so we will listen, lol!
Great demo. This is how I have done it for many years. By far the best method.
Never noticed anything but honesty.
I was taught to get quickly to near size and sneek up on it 60 years ago.
What a disaster, it haunted me for 40 years until I thought about it.
If seeking little microns, then obviously workpiece and tool tip temp deviations do matter.
Similarly different depth of cuts will put different downward forces on the tool and work-side of the toolpost, these deflections will again be miniscule but any deviations will affect the "size of bite" that the tool tip takes.
We know carbide tools like to cut deeper than HSS, so we know that the depth of cut on the workpiece is Not always linear to the dial, the tool type or grind and depth of cut etc will have an affect on scale linearity.
Thats why the finish cut should be "a balanced bite" exactly as Stefan says.
There are work thermal expansions and stress deviations, there are tool thermal & mechanical deviations.
We may think in error that we have control of the ways backlash by only turning the tool feed (or mill table) 1 way into the work but while there is no backlash available on one side (the pushing side of course) of the top-slide or cross slide, that really means that All of the backlash has become available forward of the tool travel.
The backlash does'nt magically vanish!
If the tool takes a bigger bite, it will pull itself further into the work for a smaller finished diameter.
I have watched video this several times. One of the most important tutorials for those of us who are learning the hard way. Thanks
i think i speak for the overwhelming majority of your audience - you are *not* arrogant but you are meticulous, careful and exact . . . those are some of the reasons we like you.
[ that and your excellent German sense of humor!!!!! ]
Great information! I’d love to see more “good practices” tutorials like this. Just what us newbies need. For the mill as well.
Dear Stefan, you are not arrogant, just experienced. This video is very interesting to me as I tried to make a backing plate from 4140HT and found it very difficult to machine. Hitting a precision bore has been difficult on my lathe as I have been doing the "sneak up on it" procedure. I sincerely appreciate the knowledge transfer.
Thanks! Your so called harsh comments about hobbyists sneaking up on dimensions really caught my attention. I instantly recognised the problem I am having as a novice: overshooting when you are so close. Thank you for being a straight forward teacher. I didn’t mind in the least (but then again I am Dutch and pretty direct myself). I will try your approach and see if I can replicate it. Thanks again, very helpful this video.
Absolutely fantastic and straightforward demonstration of turning to a precision diameter, along with just the right amount of theory. For what it's worth, I don't think you sounded terribly arrogant, it's just the honest truth that I think nearly anyone who has scrapped a part *raises hand* can relate to.
A+ Material
Stefan that's what we are here for. It's to learn from you for most of us. Sometimes the truth must sting a little in order for it to sink in. You are one of the best I've seen at your trade. I really enjoy your channel and way of teaching.
You Sir are nowhere near arrogant! You’re a great teacher and a wealth of valuable know how. Great breakdown and explanations. 👍🏼👍🏼👍🏼
Stefan, I can't tell you have extremely timely and useful this has been. I've been in the "sneak up on it" camp for years, and now I'm liberated and can get to the precise diameter every time, no fussing around. Thank you. Thank you. I should say I'm using the DRO, not the hand wheels, but still. Now, about that MultiFix - please 'splain.
You can't do enough of this kind of video! Cheers, Matthew
Thank you so much for the the reminder. Being a new machinist, I did learn this in school, but I forgot about balancing the final passes, so I've been stuck "relying" on tolerance to keep everything out of the scrap barrel.
I gleamed this technique from watching some of the professional youtube machinists and started trying it out. I started hitting my targets much more reliably and easily. Thank you for going over the reasons behind it. Very helpful.
You didn't sound arrogant at all, You sounded like a very competent machinist giving sound, correct advise that will help people that are less competent than yourself.
Great work, thank you.
Excellent tutorial. Thanks for sharing your expertise Stefan. Knowing what you are talking about is not arrogance in my book. Stay safe stay well. regards from the UK
I learnt this method maybe a year ago. It was an absolute game changer
Also don't worry about the cables. We all know you have trained your lathe well enough not to grab them!
Hello Stefan from sunny lockdown England. I have to admit that for years I have been chasing down the diameter of close tolerance parts with my Wabeco lathe. After seeing your video I have tried your method and have seen a remarkable and straightforward method of getting precision results. I feel somewhat humbled!! Thank you for the method and for your excellent videos. Best wishes Adrian
This is a great method, Stefan. Thanks for taking the time to show this. I did very similarly and wrote every step down to keep track of the change vs cut depth and used a scratch pass or spring pass to finish. I have also done the spring pass twice on the same setting to get within .0002"
I think the point of balanced cuts is to keep the cutting forces similar, therefore deflection of tool and part stay the same and that allows to cancel out by dialing the difference from nominal diameter. With varying cutting depths you'd get a different deflection every time and that leads to errors.
Thank you. You explained it so well. As a general repair shop guy who's learning while working, you give master classes all the time that make me better at what I'm doing, and let me raise my standards.
No arrogance received, just shared knowledge.
Looking forward to more beers and blogs with the boys (hint hint)
Cheers
"Quite OK'ish" I love that Stefan. That's definitely my league. Thanks Stefan!
I was taught to check the diameter by taking a very short width cut, say 3mm, and then checking the diameter before running the whole length of the cut. It gives a final check that the calculation is correct and the machine is behaving as expected! Great videos Stefan.
Good evening everybody,
this comment is the icing on Stefan Gotteswinter's already fine cake - I saw the technique you write about firsthand when assisting a boring mill operator a few years ago. It is useful when you JUST CAN'T MESS UP that diameter, or the part will risk being scrapped. When machining a 76 mm G6 bore on a 2 ton welded steel fabrication, the operator would come in with the boring head, left a so-called "print" on the bore about 5 mm deep, measure with a three-point bore gage, and make the final adjustment on the boring head's tip.
It works just as well with lathes on shafts, and bores, if you are willing to accept that those 5 mm will be veeeery slightly different in surface finish.
Anyway - excellent work Mr. Gotteswinter!
Mauro from Italy
I don't see how anyone can thumbs down this video. It's an excellent presentation. Thank you Stefan.
I am happy to hear this approach to precision turning. I have found that I rough down to about .025" and then split it in 2 and take 2 cuts which is exactly what you said, I can hit my size very accurately. Thank you for sharing.
Hi Stefan, Just wanted to say hi. I've only recently picked up your channel and I must say, I am really enjoying watching all of your projects, both past and present. I have a home machine shop, mainly for hobby projects but I also do some custom work to support the investments. Watching your channel has given me a lot of motivation and new ideas to improve my tools and machines. I hope you steam engine project is still coming along? My father is also a model engineer, building 2 steam engines over the past 50 years, and that's where I picked up the bug. These toys take years to complete and don't always fit into life's daily grind. Wishing you all the best and looking forward to your future content. Stay safe.
Oh my goodness. Every day, you turn out work with fantastic precision, and selflessly share with us the techniques you use, and then apologise for seeming to sound arrogant ? There was no hint of arrogance, on the contrary, you're an expert passing on hard earned knowledge. I am humbled by what you do and the way you explain so carefully. Stefan, you are an example to us all.
“We’re not chasing microns” - since when?
"We're not chasing microns"... Earlier in the video, he was shooting for 16 +-.02 and he declared 15.999 "okayish"...
I’m a convert! I just went out to my shop and hit three target diameters within a half of a thousands on my lathe using the technique you showed. One of the diameters was spot on. Thanks! Chris
I'm a machinist by trade and and work for our University with lathes nearly every single day. Still I enjoy watching these videos, looking for hidden specs of information. Thanks Stefan! I like your work
!
Sometimes the perception of arrogance is an affirmation of skill. You are not arrogant you are just a very skilled machinist. Keep up the good work
Love the fact that the lathe sounds so smooth and quiet. Quality indeed.
Thank you Stephan, yet again helping by explaining good, sound practice.
This was also how I was shown in trade school decades ago and has worked consistently though the lathes have varied in quality and wear!
A variation would be to use a roughing tool to get to your start point for 3 balanced finals of a depth of cut that your chosen/known finishing tool likes.
You reach many hobbiests, just please don't stop making videos, we love 'em.
Stefan, please do not apologize. You are by far the least arrogant person on TH-cam. You always take time in your videos to teach hobbyist a bit and if we pay attention we always learn something. Thank you.
Worked exactly as advertised, now I just have to try not to forget it before I run a lathe again!
sounds like what the shop teacher said 30 years ago,most likely just what his teacher told him. thanks for sharing!
Thanks for the very clear demonstration. I've lost count of how many times I have scraped parts trying to sneak up on the final dimension. Next time I am definitely going to try this method.
I would love to see a similar video on how to using a boring head to get dead-nuts onto the target diameter. I understand the theory of the two-equal steps method, but applying that to a boring bar with super tiny markings (instead of using the DRO for OD work) is a real PITA. Any helpful hints on boring bar use with something like a Criterion boring head would be very welcome.
Well this is super confidence inspiring as its something I already do without being specifically taught. I'm guessing I've just picked it up subconsciously from watching the right people on here.
Excellent explanation of a standard technique Stefan, as on all turning on a standard lathe, you are experimenting on the fly.
Great vlog thanks for sharing.
I am EE/CS engineer, not trained machinist by any means. Knew about this technique but still use small DOC. I find producing brass dust with carbide insert relaxing. Chasing last micron with sandpaper also has health benefit. Glad to hear that I am not the only one. Bought 40 year old abused lathe only as stress relief from work. I enjoy Stefan's videos and admit I started learning machining because of him.
That's a great tutorial. I would love to see one on the different types of materials and the tips and tricks that go with them (bronze, aluminium, stainless, plastic, ...)
Hey Stephen, another solid video.
My first job, in 1979 was turning commutators on electric motor armatures on an ancient South Bend lathe. Worn out ways, high speed steel bits held in a lantern holder, and 10 minutes of instruction - good to go.
When I went on to do more precision work, where I had to actually hit a dimension, rather than just cut a round feature, I had the exact problem you describe.
Try and sneak up on it 0,025mm @ a pass - and end up undersize. And ask myself, "how the f*** did *that* just happen?"
There was no TH-cam to tell me that my setup had rigidity issues, or that correcting my practices would help make up for the deficiencies in the machine
By the way, I got to admit I cringed a little for a second when I saw that dangling cable. Then I realized that it probably appear too much closer to the work then it really was, because of the camera angle, and that even if it did get caught in the work, it would just break the wire, and maybe yank the mic off of your collar.
Incidentally, I learned the lesson about having long sleeve shirts near the exposed back gears of that same old South Bend lathe.
Looking back, I can't imagine turning a teenage boy loose in that environment with no more supervision than I had...
Thanks for simplifying what I all ways struggle with Stefan
Just math , no magic .
Thank you for this, Stefan. Something to keep in mind and not arrogant at all.
Thanks for sharing this, I used this technique a few days ago with a boring head to turn a shaft on my mill, and it worked wonderfully! (Running the mill in reverse, with the boring bar facing inwards -- I don't have access to a functional lathe right now, and in this case the material was too large to hold in the mill spindle.)
Excellent presentation, I've seen this technique mentioned before, but never fully explained start to finish as you have.
haha, Stefan, no apologies necessary, you were 100% correct in "my" case of a hobby machinist's mistakes of using small cuts WITH insert tooling .. I haven't even finished the video but needed to comment :) Now I'm hopefully going to learn how to do it right and avoid scraping parts .. or, in my case, accepting non precise parts (and have it bug me for a few weeks) .. thanks for the video(s)!!
I hope all is well with you good sir... Always looking forward to your next video.. Thank you for making them for all of us to enjoy, and learn... Stay safe..
Thanks, yes, all is well :)
New video coming soon!
This is indeed the best technique to do it on a manual lathe. I think you should have explained why this works also, helps especially the beginners to understand why you can't try to finish accurately with a single pass and why the sneaking is unnecessary. Namely, evening out the deflections that the cutting forces cause in your whole setup for the last 2 passes to get a reliable reading when measuring the second-last pass for what you need to take on the finish pass.
Did you actually watch the video? He explains that quite clearly...
@@elanjacobs1 I didn't hear him mention deflection but the fault might be only in my ears. I'm not a native English speaker so he might've told it somehow between the lines without me realizing it. The subject was clear for me partly because this is how I do it as well but I was thinking about the absolute beginners.
Great video, these are great for beginners such as I was a couple of years ago, and still have a ton to learn!
Prof Gotteswinter, when is the next "basics" lesson?
I second this. I am very keen on watching any more of these back to basics lessons you might have Stefan.
I so needed this video! The amateur you talked about who tries to sneak up on the final diameter then suddenly he's overshot and the part is scrap... that's me!!
When I can get to a lathe again (the hackspace is closed due to lockdown unfortunately) I'm going to be trying this out.
I remember discovering the balanced cuts approach and it works every time! I tend to do 3 or sometimes 4 just to make sure I’m on track. Creeping up sometimes works if the material is very soft but otherwise it just won’t cut at all and you keep moving the cross slide until it suddenly bites but now you have overshot the dimension. Also liked the **cough** solid toolpost **cough*. Waits for the next ToT upload ...!
It all depends on the nose radius off the tool you use how small cuts you can take/sneak on to the diameter you want, the same technique works with a bore and also for milling precision fits.Tool load worn thread pitch and play is affecting the precision
Another great video Stefan.. Some great tips here... Looking forward to the Multifix video! Take care, have a great week!
Excellent, precisely explained video. No arrogance taken; and thanks!
Great video, I am one of those who is guilty of creeping up with no reel plan and over shooting all the time. I look forward to implementing this balanced approach.
Solid info on machining technique with a pinch of double entendre tool room humour ... better than telly.
Another excellent presentation. I'm sure this will help me make better parts.
Not arrogant at all, Stefan. it's just a good tip. I use it for a while now and it works very well. Thanks foe sharing.
Nice to get your take on this. I’m learning my way round a lathe and I always sneak up in sizes out of fear of scraping a part. I’ll try this next time. Cheers
Thank you Stafan, I've only been turning for a few years but I learned quite early on that "sneaking up" to a final dimension was hit and miss at best.
Will be using this technique once I've made some new dials to replaced the useless ones that are currently on my lathe.
You were just telling the best and most repeatable way.
Thank you.
Bro,
I think it's safe to say that you've more than earned the right to sound as arrogant as you want lol
My favourite technique has always been to cut things a little oversized and then obliterate the surface finish with spring passes. With a surface finish that bad, you can usually find a place that's in the tolerance!
In all seriousness, awesome video!
Thankyou Stefan....EXCELLENT procedure!
Great video as always, Stefan! The one thing I would add is that if you're running a lathe that isn't in great condition or that starts with a lot of torque, or that needs some maintenance and leveling, etc... people should consider restarting the spindle before dialing in their cut. I have blown a tight tolerance or two before by dialing my cut in and then starting the spindle and if you watch a DRO or a dial set to read on the cross-slide you will often see the numbers change from the machine shaking a bit of error out.
Again, great video. Thanks for posting it!
Thanks stefan. This is the way I started doing it , because it made sense in my head to try to control, or even out the variables when making precision fits. Surprisingly, most of the old guys in repairing enviroments tend to sneak to final dimensions, and to me it never felt right.
One point for older lathes, backlash on thread on cross slide needs to be taken into account when setting the datum points, so always feel the engagement of nut in one direction.
I had to watch this again. It makes perfect sense. Sneaking up hasn’t worked well for me.
Thank you for pointing out clearly which method is the way to go. Even though I knew the method of balanced cuts I caught myself to sneak up on diameters if I am anxious to ruin a part.
Hey Stefan, many thanks for that demo!
I think, at the last part, you missed a micrometer reading: shouldn't you mic before the first balanced cut? Or else, it doesn't exactly serve you for setting the machine.
Describing the process in other words:
- know your tool, find the DOC (and speed-feed) where it's happy
- rough down till 2* DOC oversize
- take a mic reading
- take first balanced cut
- compensate
- take final balanced cut
Many thanks again for the demo!
Excellent advice Stefan, thank you for taking time & effort to create a great demonstration video. Very helpful indeed.
We learned the careful tiny final cuts approach at school, 40 years ago. Strange they had not yet the logic of balanced cuts in these days.
at least you're now back to the multifix gang. ^^
maybe some additional advice: using a roughing insert for finishing cuts is cost effective for sure, but considering precision it's always better to switch to a finishing insert with smaller edge radius with T, D or V geometry. and as a rule of thumb for the DOC when finishing: never go below the actual edge radius and try to use convenient numbers like 0.5mm DOC for 0.4mm edge radius or 0.25mm DOC for 0.2mm edge radius as it enables the chip breakers much better for chip control and the cutting forces are more balanced with an additional axial component.
Thank you again Stefan!.Please keep up your great channel!.....I have been failing with the "sneak-up" technique ever since i took this up as a hobby.....Now I want to go and practice (7x10). THANKYOU AGAIN for the great presentation :-) Mit Freundlichen Grüßen Richard. .... Mid Wales (UK).
This is exactly what was told to me at my internship. 2 balanced cuts to hit your dimension. And keep your nose radius fully engaged. Worked perfect, 150 h8 till parts as small as 4h6.
Good Morning, Stefan. Hope you're staying safe! Now on to watching the video :-)
it's probably evening by now in germany
@@multiHappyHacker 13:52 by the time this comment was written ;)
We all know that you don't want to sound arrogant Stefan. That's not in you. Thanks again for a super video.
Thank you, this helps me solidify my muddled thinking on this topic. No more sneaking
Hi Stefan, thank you for this. Your "intermission" was not really needed, but appreciated none-the-less. You were simply speaking from experience.
PS: you might need to get that cough checked out! :) Stay safe and well.
18:44 "The same technique works of course with a bore..." and not only for turning but also for milling precision fits ;)
THANK YOU, PROFESSOR GOTTESWINTER, THAT WAS EXPLAINED SO WELL , IT ALL MAKES SEANCE. REGARDS RICHARD.
Thank you that made perfect sense because I have used the sneak up method and have lots of junk parts. I will be trying you method and I will be working on removing my compound and building a lot more solid tool post to hold my multi tool holder.