How to cut a thread on a manual lathe (Intermediate method ideal for home workshop & hobby engineer)
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- เผยแพร่เมื่อ 5 มิ.ย. 2020
- How to cut threads on a lathe is a fundamental skill of any machine operator. This is an intermediate method that is ideal for most applications and lends itself perfectly to the home workshop and hobby engineer. Cutting threads on the lathe this way is both fast and low risk. The basic way to cut threads on a lathe is very slow. The more advanced way to cut threads on the lathe is a little more risky and you are more likely to make a mistake. It's not hard and i'm sure you are more than capable, there is just more to do and therefore more opportunities to make a mistake. I think this method of cutting threads on the lathe is a good compromise between the two. The beauty of cutting threads on a lathe using this method is it is very versatile. If you need to stop thread cutting and do another operation you can just come back to it and the tool with pick up where you left off. You can't to this with the basic method...
I was asked to make a new motorbike axle for a friends flat track motorbike. The axle is turned from S275 which is a steel with a yield strength of 275 MPa. It machines nicely and has good shock loading properties making it ideal for this application. The Axle consists of three diameters with an M14x1.5 thread on one end for a nut.
Here is a recap of the order of operations for cutting a thread on the lathe using this method.
First set up your part, tool, speeds and feeds.
Colour in the area you want to thread and do a scratch pass.
Check the scratch pass with a thread gauge.
Cut your threads.
Clean up with a file, emery paper, and scotchbrite.
For the actual thread cutting:
1) Wait for your number on the thread dial indicator
2) Then your number lines up, engage the half nuts.
3) The thread is cutting.
4) At the end of the thread, dis-engage the half nuts.
5) Withdraw the tool in the -X Direction. (+X if threading internally)
6) Move back in Z direction to your start point.
7) Put on your next cut and repeat until down to size.
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Rob
- Handmade Extreme -
Disclaimer: This video is meant for educational and entertainment purposes only. It is in no way meant to be a set of instructions and therefore no attempt should be made by any party to recreate what has been seen in this video. Any attempt to do so is done completely at your own risk. - วิทยาศาสตร์และเทคโนโลยี
It is more imortant that you are taking the time to show someone how to do something . Good on ya mate
Nicely done sir. In the early 80's I was fortunate enough to have my employer fund a full 5 year mechanical engineering apprenticeship. This Brough back happy memories. Excellently and precisely explained.
Thank you. I'm glad you enjoyed it. I too was lucky to be in a similar situation where my employer at the time put me through college. On the job training or 'learn as you earn' is a great way to gain both knowledge and experience in my opinion.
I agree the method is right, but I would have loved him to javelin shown the method of using the compound rest at 29.5 degrees. That's the traditional way it was a taught and I feel it's easier to pick up a thread for repairing threads as well.
However, great video with good explanation and the method isn't incorrect in anyway tbh.
Superb video mate,& demystified manual threading massively for me- been having to use retention screws instead of threaded parts on my hobby project due to lack of time to get trained up,& this has given me a mental grounding in the process to get started threading future builds.Brilliantly clear explanation- much obliged,sir!
My father used to do a 14 feet long shaft with ease.
I was about 11 or 12 years old maybe. He was a great turner. Passed away in 2012.
Wish he was alive to teach me all this stuff.
That's how I learned it during my apprenticeship but we also rotate the toolpost. Very good tutorial!
You just earned a subscriber. Just started to look for a metal lathe and gathering some information on various techniques and this one is very concise. Excellent job !!!!
That was a brilliant lesson on thread cutting. I'm a very keen hobbyist and self taught. Your lesson has taken away most of the scary stuff for me. Thank you very much
Glad it was helpful. Good luck with your own projects. 👍
This is the method I have learned on the manual lathes. and always used. I used to make spindles for axles on semi tractors and stuff. Then I went to school for CNC and was smitten. Thank you for explaining this so well
Your welcome. Glad you enjoyed it.
Excellent video!! I have seen dozens and dozens of videos of thread cutting. This one is by far the best and most well explained!
Thank you. Glad you enjoyed it.
Great instruction with perfect clarity. Thank you for sharing your insights via this video!
Nice video for demonstrating cutting metric threads, may also add depending on what brand of lathe swapping gears to do metric or atandard threads. Ive been cutting threads on old school lathes for 35 years myself,over all great video
My two cents worth……..engaging and disengaging the half nut lever is only done when you are cutting very long threads. With most typical threads such as this you simply withdraw the tool quickly at the end of cut and put the machine into reverse to get back to your start.
I agree. Where you disengage and engage the half nut, it doesn’t always go back exactly the same. Especially with an older lathe. You can easily cut the thread too deep or too wide usually when doing final cuts.
Flip the tool upside down, and start the tool from the chuck side and feed toward the tailstock and run the lathe in reverse. Learned this from the best toolmaker I have ever know who was from Germany. Many advantages, the most important is that the chips fall down out of the groove instead of bouncing around in the groove and ruining the finish. Running off the part at the end is more forgiving and gives you more time to disengage the half nut, therefore you can run the rpm higher for smaller diameters. And no, you won't cut a left hand thread this way.
Dude, you dont even know that you saved my sorry ass right now, thanks😁
A great method as long as the chuck doesn't unscrew and follow the chips into the chip tray. Make sure the chuck is locked onto the spindle thread. 🙂
This is also a better method for parting off.
But don't do this for any heavy turning op's as the force is not directed down into the machine.
Just subscribed, recommended by my brother Carl Wilson. That was as good an explanation as I've seen on TH-cam. I like to make the gutter to the thread depth, that way when it scratches the gutter it's a good indication that you are pretty much at full depth. Tipped tooling is great because it gives you an indication when you get to the flats anyway. Great video. Dean in Oxfordshire.
Ahh, another Wilson. Welcome to the channel it's great to have you here. I'm glad you enjoyed the video and thanks for the tip 👍
This is a good, thorough, tutorial covering ALL steps in setting up the machine. I would offer to immediate improvements to ending up with a better thread. The first being a faster spindle RPM. It appeared the RPM chosen was simply the slowest ...which is fine. But the problem is this cutting speed is in fact very slow ....on purpose.
1) A faster CS would automatically provide a better finish on the thread form. But this is up to the operator and their comfort zone with operating the half-nut disengagement only, for this one example. As determined and explained, for this thread pitch, any of the 8 engagements on the thread dial indicator will keep the pitch ...so there is no challenge factor in engaging ....and this engagement can be as far away from the thread start point aw the operator chooses. It is the "disengagement" that is the critical point ....but this is also dependent on how wide the relief is. Nothing wrong with practicing this technique. It just requires concentration.
2) The depth of cut chosen was very deep on the second pass. Considering the extremely low RPM, this resulted in extremely poor surface finish because the metal was literally tearing off the parent material ....and the surface finish looked awful. The depth extreme depth of cut can be taken, but it need NOT be that deep. As the final thread depth of cut is approached, the actual cutting depth should be reduced, simply because there is more material being removed at the deeper cuts.
3) And lastly, it is very common practice to run at least one "extra" pass after the last finish depth has been reached. Even though this bar is supported on a center, the bar material still deflects. There was a lot of tool pressure still on the last cut. A "cleanup" cut just makes sense to perform. It will literally always improve the thread surface finish as well .....which is what the female thread is going to be running on.
There wasn't very much offered about "fitting" the thread and the testing of the nut did not reveal very much either nor was there any mention about the fit/class .....but considering this was only a tutorial using the cross-slide, ....enough said.
Great video .. in my school days we did so much theory on how lathes worked and then never got to use one.. now I'm at an age I can maybe buy my own and learn.
Many of your viewers (me, for instance), have less rigid lathes. If I try to plunge-cut a 1.5mm thread on my seventy year old Myford Super 7, I will end up with a lifetime supply of chatter marks!
For lesser beings like us, the 29.5 degree compound slide method is our saviour! Sadly for me, my lathe is also short of its thread-cutting dial... My father bought the lathe when I was five years old, and gave it to me thirty years later, so I know it did not ever have a dial... might be a project for me. 😜
Great video, thank you. It did drive me la-la though; your voice is very familiar, but I could not figure out why! 🥴
As an afterthought... because the Myford has a clutch, I can make a cutting pass, disengage the clutch and withdraw the tool, then wind the carriage back using the handwheel on the leadscrew. This is actually a very quick process, and works great with the 29.5 degree compound, and no threading dial... it's also pretty foolproof. 😛
Excellent, concise and honest presentation. No verbal diarrhea ... just tell it as it is. Well done ... thanks.
Your welcome, thank you. Glad you enjoyed it. 👍
Nicely done, sir. Excellent organization, camera work, sound and editing. It is one thing to know how to do the operation and entirely another to be able to communicate it effectively.
One thing this illustrates is the difference between a shop lathe and a small lathe like a Sherline that may have the lead screw gearing to cut threads but lacks refinements such as the dial.
Love your cnc X and Z axis references on a manual lathe.
Cheers, Glad you enjoyed it.
Manual machines have the Axis as well
Great video mate! I came originally for the transit caliper rebuild but now I’m fascinated!! Cheers
Thank you for the support. Glad you are enjoying the channel.
Amazing tutorial, so informative, thank you!
This is the method I learned in school, great job at making info more accessible.
Glad it was helpful! Thank you.
Cheers mate. Nice refresher.
Just found your channel as I've upgraded to an M300 from a Myford and liked your RPC video.
If you're just doing a simple "plunge cut" threading job and you have the nut handy for sizing, advance the top slide a couple of thou every cut, this mimics the angled top slide method and let's the tool cut primarily on its leading edge, reducing tip loading and generally provides a smoother finish to the threads.
Nice idea. I'll have to give that a try some time. Thanks for the support.
Comprehensive and clear. Thank you.
This is the way all 'how-to' videos ought to be made - concise, but still quite instructive. Very well done indeed - thank you!
Another great vid, thanks! now, I just need to work out a way to get a lathe up all those stairs into my flat :) Luckily, I've a great mate who lets me play around on his whenever I want, I just need to convince him he needs a mill, surface grinder and a shaper next, 👍
Hahaha better buy him a few bears. Glad you enjoyed it and thanks for the support.
Absolutely awesome vid! Much respect and gratitude from New York
Thanks, glad you enjoyed it.
Looks amazing... Nice video!
Great explanation there that gets straight to the point.Well done.
Thank you.
I don't have a lathe and I found this very interesting. Thank you
This is great info! Thanks very much for the demo!!
Nice job explaining what can be a very complex procedure. Also for showing the importance for learning the parts of the lathe.
I might suggest for some that one way to speed up the process and to get very good results for the thread cut depth is to rough the thread to a size close and then run a thread die cutter over the rough cut thread to finish cut. That way you will have started the threads nice and straight as a lead for the thread die. Use the thicker thread cutting oil for a nice finish too.
We used to do this because even a slight distance off on your depth can cause major problems either too tight or loose. Too deep and you made scrap.
If you’re experienced enough you can place the thread cutter in the holder and let handle rotate up against the carriage. Turn the lathe on slow and stop the machine just before finishing the cut. Let the handle follow the carriage. Finish by hand and reverse the lathe holding the die cutter handle.
This allows a straight precise thread every time that works. Most people can’t cut threads by hand without going crooked so they cut a rough thread and finish by hand.
Brought back memories and using the thread gauge rods to measure groove depth. Learning how to read and find the information in a source book is a lesson in itself!
Thanks for sharing
Always wondered how this was done. Thank you!
Great video! I really appreciate the detail you used.
Dude that was awesome 👏
Thank you for sharing this
Glad you enjoyed it! Thanks.
Very concise explanation, cheers!
So THATS the part I forgot to do, been a while since I've run a lathe and I was running some practice passes a bit ago on some plastic and a few times I cut right through the high side of my threads, wasn't sure why, now I know, I got certified as a machinist when I was 16 and I'm 22 now so I've forgot quite a bit, tryina get back into it and you just solved my issue, I knew it had to be something simple, I just forgot to wait for the number to come around before I engaged the feed
Thank you I just bought a lathe without a compound slide, only a tool holder on the cross slide, I think I can cut threads with it now.
Excellent tutorial! Tyvm 👍
Brilliant Video for learners.
Thanks for showing great tutorial ,nice and simple
Great video explaining this process. Thanks.
Fantastic, very easy to follow. Thanks for sharing
When I started my apprenticeship, I was taught how to calculate the thread depth (using simple mathematics). The second thing I learned is that when you did the final cut and the nut fits perfectly, NEVER to use a file on the thread or "scotch brite". The thread should be smooth and shiny. In this video, you can see on the "chip" that there is chatter. However, a good tutorial for a beginner !
Yeah, this video is pretty scary to watch. He's going way too slow to get a good finish and I don't understand why you wouldn't turn the compound to decrease chatter.
Could you share the info on how to calculate the thread depth?
@@spazzwazzle he said that there are better ways to do the job ...but this is a fairly basic method with less chance to make mistakes... i am sure he could do if he wanted to
Excellent video demonstrating basic thread screw cutting and very well explained how you go about it and why you do things the way you do. Only difference in the way I do it is I turn the compound slide around to half the angle of the thread im cutting so that the depth of cut increase on the compound slide is following along the back edge of the thread and the tool is only ever cutting on the front edge, gives a nicer finish but is slightly more complicated for the lathe operator. As always learn to get he job done first then you can improve your skills and methods as experience increases.
Smashing, brilliant, awesome!
thanks for sharing this method.
I will check it out on my kather when it arrives.
excellent video, brother!
That lathe is wicked upscale compared to either of my lathes.
Very good demonstration thank you
NIce lathe, good tooling, good job, good worker and excellent teacher. Thank you 😊
Thank you, great tutorial.
Brilliant info on this video
Nice video shot, keep it up, thanks for sharing it :)
Excellent video, it's very well explained and filmed. Thank you so much to you.
Glad it was helpful!
Interesting, very inspiring indeed. Thank you
Excellent post.. straight to the point with no excessive verbal chatter (:0)
Realy enjoyed that 👍
Dude this is so great. I have always wondered how this worked. Because I have seen loads of videos where the camers is focused on the cut while threading but with no explaination. I just assumed the person using the machine practiced their timing enough that they were just that good. I am not ignorant enough to assume it was like mastering an "etch a sketch". But my interest lead me here because I want to know. I wish I could meet someone that could traim me to use a lathe. I would learn for free in exchange to benfit the master on my spare time. This is some of the most interesting stuff I have ever come come by. My wanting for things to be precise, mechsnical inclination, my ridiculous attention to detail, and drive would come in handy. Time for another career change, what holds me back is that I do not have the freedom, nor can I afford to start off as a newbie. This is it though. I know it.
*Typos
I have a lathe with an imperial lead thread so need to change gears to cut metric threads. I always cut straight in and much prefer to cut away from the chuck. I prefer to use HSS steel tools though I do have carbide inserted tools. I also have made an inside carbide tool for small inside threading. Well done video.
When the thread chart says 1-8 you can engage the half nuts on any one of those numbers. You can also use a different number each time you engage the half nuts as well.
Nice work sir,excellent.
Very Clear explanation! Thanks
Your welcome. Glad you enjoyed it.
Just found your video good quality all round & the lathe it speaks for its self, just subscribed, Coventry Uk 🇬🇧👍.
Welcome to the party, great to have you here. Glad you enjoyed the video and thanks for the support.
Good to see an instructional video with carbide threading inserts , only thing I would add is carbide inserts give a much better finish at higher speeds , something to work your way up to if you're disengaging the half nuts and you've got good hands.
Absolutely right. Got to have quick hands when doing it manually at the higher speeds.
Appreciate the comment. I was wondering how slowing the lathe way down was affecting the “speeds and feeds” equation. Presumably a high speed steel cutter would work better, perhaps with some tuning of the tool geometry? The trade-off is: if you don’t already have the tool in your inventory, you might spend more time grinding the tool than what it takes to make the part.
In any event, the thread seems to be mechanically sound and passes the cost/benefit test. Comparing the final thread with one cut with a die would be an interesting exercise.
Really good video nice and clear. Thanks
That was excellent, thanks, a very good explanation. That's my chosen method too. With inserts I think it's totally fine to go straight in with the cross slide and cut on both sides. These days I tend to keep the half nuts engaged, because I set my VFD up to have a fwd/rev switch for threading. I have programmed very fast deceleration times for the motor when run from that switch. It's a bit like having a clutch, as on the Harrison 140. I can stop dead, back the tool out and reverse the carriage. I need to make sure I cut a big enough drop out groove though, first!
Thanks again, really enjoyed.
Cheers Carl,
Great to hear from you again. Nice move with the VFD. Luckily I have a foot brake on mine if I need to stop it QUICK.
Thanks again for the support. 👍
@@Handmadeextreme No problem. You have a great lathe. Very useful tool. I'm looking forward to the next video about the car too.
Fantastic..amazing work...
Thanks, this is like having a virtual 'over the shoulder' look within a machine shop - I have a small imperial Holbrook I acquired from my old Chemistry teacher's dad who was an RAF mechanic and then a technology teacher before he suffered from health problems and had to have his basement workshop cleared out - there are so many bits he had made for it I have no clue what many of them do as they only taught us basics at school - I would love to be able to use the thread cutting feature but am too scared I'll mangle the whole lathe doing so!
Great video, thank you, what is also awesome is the tips from the "knowledge network" in the comments section, however, the way you explained this is great for beginners like me, get comfortable with the basics and throw in the all the tips below, JUST AWESOME...
cheers.....
I was taught to turn tool upside down, run lathe in reverse, and cut from chuck towards tailstock. This reduces the risk of a crash into the shoulder, and no need for a large undercut. I always cut threads this way, and have done for last forty-five years, unless using an Ainjest attachment.
Martin 1299S: that is a good method if you have a good lathe, but it does tend to be lifting the toolpost off the bed, rather that pushing it down.
Great explanation, thank you very much!
Glad it was helpful!
Would recommend using coolant when screw cutting you will get a much better finish, when I served my apprenticeship in the late 70s I ended up doing all the 2 and 4 start threads for the marine engineering company I worked for; that’s advanced screw cutting 😀
thanks man....
great video
Very good , thank you!
Absolutely amazing video !!! Thanks for sharing and especially for throwing in the mistake because I make that mistake all the time !! Liked and subscribed
Glad you enjoyed it. Welcome to the channel.
I got 11 cars and several motorbikes. I bought a lathe for this kind of projects.
I remember the first time I cut a perfect thread. It was like I'd mastered witchcraft!
Very well explained.
Excellent video
Im about to start working on one of those, i have basic knowledge but it would be great if you had a video explaining every feature of the machine
Nice and great job 👍👍👍
i always wondered how threads were lathed, and i never imagined for some reason they are just built into the machinery, as a function even on a manual one lol. for some reason i thought i was gonna be some etcha sketch magic with 2 knobs for feeding and cutting or something lol thanks for the vid. still crazy the manual timing amazing
Suggest you check Colchester training films on screw cutting. They show the topslide set over at half the thread angle. The cut is applied using the topslide with the cross-slide left at zero.
So you are only cutting on one edge of the tool, the other side of the thread being generated by the top slide.
Funny this should come up. I have a Myford ML7 and I was doing an internal acme thread yesterday. It's a bit of a challenge.
Muito bom trabalho. Excelente explicação.
Very helpful and easy to understand, keep at it !
Thanks Jack, I'm glad you found it helpful. 👍
hello
join me at facebook to learn more gideon de hit maker
Phwoooooaaaar! That's some good lathe operation!
Haha, thanks glad you enjoyed it.
Great little video and I still cut threads with this method.
Cutting speed is way to slow as the tool is tearing the metal not cutting it.
Coolant or Rocol will help with tool life and finish.
Did you set the tip square to the job?
Thank you for your tips. Do you have a video to do a self reverse scew?
Great video 👍👍👍
Good video editing. I also have a metric Harrison. For the thread you were cutting you can engage on any number every time. You seemed to use 8 the first time, then wait for 8 every time you re-engaged. You could re-engage on any number. Try some “air cuts” to prove it.
Thanks very much, glad you enjoyed it. For that thread your absolutely correct. I think I might have just reused the same bit of footage each time. Takes a lot time to set a shot up so reusing the footage saves a bit of time in production.
Thanks for your support 👍
I bought a used Harrison AA. I took apart the cross slide dial assembly to clean and destroyed by mistake the 2-pin circular locking ring that holds things together. Tried to fashion a new one but cannot get the right size/pitch to go on smoothly. Any idea what those numbers could be?
It realy helps me thank u so much
That's ok. Best to run in CCW thread from left to right. Use a hard saddle stop or DRO for Z0.
You are really unique, thank you for your efforts, it was great.🙏🙏🌹🌹
Beautifully explained. Very educational and useful. Thanks a lot!
I doing this from last 10 years in Singapore. And i love to make it
It's well worth getting the full form inserts for whatever pitch you are threading, especially for common pitches such as 1.5mm. You can easily tell when you've cut the thread deep enough & you get a much nicer finish with no need to faff around with a file & Scotchbrite !
I'll check them out, thanks for the tip. 👍
That insert is far too big for the pitch & will give a much larger radius in the root of the thread. So the cut had to be deeper to get the nut on that's why you machined into your undercut. This thread will not engage properly as the flanks have been machined too wide for the nut crest radius to clear the large root radius formed by using a tip that has a root radius form too large for the pitch. Also a full form insert will create the correct crest radius so no file or scotchbrite. The inserts are not designed to cut all around their profile so plunge cutting is not advised. Always advance the tool on the compound slide for each cut. You could have also increased the undercut with the threading tool.
My lathe was built before threads were invented .... if I win the lottery I will upgrade ! ( some nice tip in that vid such as highlighting the part )