Metric Threading with an Inch Lead Screw
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- čas přidán 22. 07. 2024
- I this video I show a new trick I added to my toolbox. Special thanks to Conrad Hoffman for a nice concise write up of the process. Here it is in video format. This demonstrates a practical method of metric threading with an inch lead screw allowing the temporary disengagement of the half nuts. This is particularly important when threading up to shoulders.
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After watching this, it's such an obvious solution. Makes me question my whole life. Many thanks to Conrad and youse.
That is what I love about this trade - the learning curve never flattens out .
Good tip.
Tom, Just wanted to say thanks for making this video. I was going crazy trying to cut metric threads. This was the answer!
Thank you so very much for posting this. I’m new to machining, had my lathe less than a year and was having the worst trouble cutting my first metric thread. Your video really saved the day :)
Awesome tips here! I’ve been wondering how cut metric threads on my small American lathe. As a fairly new hobby machinists, I’ve learned a ton from you and absolutely love the channel!!! 👍
Damn. I'm a prototype machinist, and I didn't know about this. I was always under the impression that you had to keep it engaged the whole time. You just made my life easier.
After a couple of broken hearts I never disengaged the halfnut all these years. Thank you for showing me how!!
Thanks Tom, excellent demo! Had just got done reading Conrad article and I noticed this video had come up in my search window and BAM, now to the video😀. Awesome job! Now threading metric to a ridge won't be so tense😎
Hi Rambler,
Conrad has some great stuff on his site. This is so simple but escaped me for many years. Thanks for the comment.
Cheers,
Tom
very good, just fighting a metric threading problem a couple months ago. will definately try this. THANKS
Very neat trick. This is so obvious when pointed out, thank you
Pretty pleased with myself, I was wondering what the heck you were going to do, then I figured it out just before you said it. Brilliant idea! Now I just need to find a set of metric change gears for my old lathe (almost impossible)
I had considered this threading method (but the opposite way i.e. cutting inch thread on a metric lathe) soon after its launch many years ago, but regarded it too complicated and forgot about it. But recently it started to bother me again. I re-watched the video and understood it better. Oh yes I tried it and what a sweet safe way it is to turn a thread to a shoulder. I am very grateful to you and your source for this excellent method. There are really no more steps than threading normal way. You only re-engage on the reverse instead on the forward. It is just that easy and fearless.Thank you Tom.
Thank you very much!!! That is really what I have searched for, no calculation, just the most simple and useful method for my chinese lathe without a brake :D
1.000.000 thanks to you Tom, I have learned so many things from you..!!!!!
Very Nice and Cool. That was nice and clever, but exhausting too. You are on the top of the world after completing a successful project not without a feeling a high. Thanks for the Video.
Wow, just ran across this video. I could have used that a few months ago. Definitely a great technique. Thanks for sharing.
Thank you for that neat trick, Bob
Many thanks for sharing Tom!
No more "Brake & Jog" for metric single point threading!
Very good demo,
Ray
On older machines with lots of backlash etc, ensure that you engage the 1/2 nut with the same amount of closure if it is variable. The other is to wind back enough off the thread for the start and I put a little of drag on the hand wheel to take up any backlash in the system, then I let go of the hand wheel before the cut starts. The main thing is not to change any gearing for when reversing etc. My other tip is to cut at a speed that you are comfortable with stopping by disengaging the 1/2 nut. This is very useful when cutting internal threads to a blind shoulder etc. I was shown this as an apprentice back in 1982. A great video .
Not watched you for a while Tom but this is a top tip was struggling with doing the same this on a lathe I recently changed and and handles a half nut lever was on opposite sides,thanks again for all the videos you post Dan
This is a super technique which should have been standard fare in all textbooks published in the last 50 years. For us who live in a metric standard country and purchase regularly from the States (Imperial dimension tools and supplies) this procedure is worth its weight in gold. I really enjoyed your demonstration (very well done) and continue to enjoy the CZcams machining community's generosity. Great stuff!
Hey Jim,
Thanks for the comment. I was as excited as you when I tried it myself. Its great to learn a new trick and add to your toolbox.
Cheers,
Tom
Thanks for the great advice Tom. Got some adaptors to turn tomorrow so going to give it a go. I have always been in the habit of keeping the half nuts locked at all times when cutting a metric thread.
Hi Andrew,
Well. How did it work out? Thanks for the comment.
Cheers,
Tom
This is a good "trick". Thanks. I have not done much threading, just a 3/4"-8 LH SQ thread on some chuck screws, and some 1/4"-20 threads where I turned the tool upside down and used reverse. I kept the half-nut engaged for the 8 TPI because it was too hard to hit the dial tick with a 16 TPI leadscrew and a little 64 tooth thread dial on my little HF 9x20.
I've been cutting metric threads for years and have never thought of this trick. I will certainly give it a go on the next job. It should releive the blood pressure problem of having to wind out the tool and disengage the clutch and still have to worry about the inertia of the machine and the risk of having a prang.with the tool runing into the shoulder.
Thanks heaps.
Hi Robert,
I know the feeling. This is so simple its a wonder its not more common. Thanks for the comment.
Cheers,
Tom
Cool technique. I have become VERY dependent on the footbrake and jog button when doing such a thread. It's nice to take some of the pressure off by being able to release the half-nut. I shall use this in future. Thanks to the original poster and yourself for the excellent demo.
Colin
Hey Colin,
Thanks for the comment. You can actually coast for quite a while. I use the foot brake out of habit.
Cheers,
Tom
I just had one of those "Why didn't I think of that" moments... Outstanding tip and explanation! Thanks for sharing Tom...
Hey John,
I felt the same way. Its so simple but apparently not obvious.
Cheers,
Tom
Super. a new tool in my box. I am thankful nearly everyday for youTube... I know there are those who curse it... but... not me.
I've used this for quite a while. I actually figured this out on my own because I thread a bunch of metric threads on my inch lead screw lathe in my ATV/Motorcycle shop. One problem I also had was that my metric side didn't cut 1.25mm or 2.50mm threads which are pretty common in the metric world. After seeing Keith Fenner calculate that a 20TPI is practically the same as 1.25mm! Now I can cut them all. Thanks for all of your great detailed videos.
Andy Maul
Hey Andy,
Thanks for the comment. Its a great trick.
Cheers,
Tom
Thanks for the video. I just picked up a set of Metric gears for my SB 10L and was thinking about how to go about using them. I figured it out about 2 seconds before you showed it. Thanks again!
Hi Precision,
Thanks for the comment.
Cheers,
Tom
Very cool Tom,
Always great to learn something new after all the years we put in to our profession. After I learn something, I always comment back,
"Now I'm smarter today than I was yesterday"
Thanks for sharing!
I'll be coming to the open house, looking forward to meeting you and yours.
Ray.
Hey Ray,
Thanks for the comment. See you soon.
Cheers,
Tom
Great video, I have a metric lathe and was struggling to cut an imperial thread until I discovered that the threading dial wouldn't work so used the keeping the half nuts closed method. I'm thinking that this method will also work for cutting imperial threads on a metric lathe, will try it. Many thanks.
Thanks Tom. Makes perfect sense, as all the good ideas do.
love it , I'm gonna do this tomorrow.. I always manually backed it off and never disengaged the half nut
Tom Lipton
Yes, even an old dog like me can learn,
after leaving a comment on metric threading with Keith F. tonight, I stumbled on your
tutorial on just that, it is a work around that I have never seen before
WOW-COOL. I have had to teach customers (angry customers) that had been sold a
lathe that should do inch metric threading and I had to teach that stop and backup routine for years and I see this and it is so simple, can’t believe that I hadn’t thought of it!
JON
Hi Jon,
I felt the same way when I first saw it. I was mad because of all those years of doing it the hard way. Thanks for the comment.
Cheers,
Tom
new student here, smart man there. I too am no spring chicken but love learning new things on anything
Thanks very much. Awesome idea I can’t wait to try it
Many thanks Tom, something we should have all thought ourselves...
Very good technique for people to see. Like most of my generation I was trained to never uncouple unless absolutely necessary and there are times when it is much easier to be able to momentarily uncouple as sometimes we were cutting inch threads on a metric lathe, ha ha - same problem. I will add that when one cuts one of the rare fractional pitches (11-1/2 TPI comes to mind here) that your demonstrated technique will prevent the "doubling" that can occur. Good job.
Hi Robert,
Yes you have the inverse problem. I am upset that I learned this trick after so many years of doing it the hard way. Thanks for the comment.
Cheers,
Tom
This is a great trick, I don't cut many metric threads but when I do I am going to give it a try, thanks.
Glad you like it. Thanks for the comment.
Cheers,
Tom
I have one of these moriseiki lathes. When I got it, it was set up for metric, with 36 drive gear. I had to replace with 72 drive gear. Am now learning how to operate this machine. I love the machine. Bought it out of a shop for $1000.00 dollars, and they thought it was european with european power. I built my own 3 phase unit and run it fine. My serial is 990.
Very good,I have am old craftsman lathe I am going to try that the next time I need to cut some metric threads
Thanks again
Hi Tom,
Good trick to not end up with a broken shoulder when working on a lathe with no pedal brake. I'll try for sure...
Today is another good day where I've learned something new.
Thanks,
Pierre
Hi Pierre,
I was happy to learn this as well. I was grinning like crazy.
Cheers,
Tom
Damn, why have I never thought of that. And there is nothing stopping you from doing the same at both ends of the thread.
I wish I'd watched that a month ago, I had a part to thread with very little room at each end of the thread. It was very stressful
This is GREAT I have always left the 1/2 nut engaged on metric threads
in the past but this makes perfect sense!!!
Another note on most lathes you can grab a faster spindle speed on the reverse
if you are cutting a long thread, as the feed drivetrain is driven directly off the spindle
and doesn't care what gear the spindle is in.
We have a couple of lathes with clutches that run faster in reverse for this exact purpose.
PS you can turn the spindle by hand for real finiky right up to a shoulder super fine
rifle scope type threads
Hey Gent,
You did the same thing I did. I went, well crap that is a cool trick. Why didn't I think of that years ago.
Cheers,
Tom
Great video Tom!
Absolutely brilliant my friend! I wish I would have thought of that a long time ago, as it would have made many a job easier. This is great for threading to a shoulder, but for through threading like I did recently I'll just keep it engaged.
Thanks for doing our homework for us, and showing us another way to getter done.
Thanks bud!
Adam
Hey Adam,
I was so excited when I tried it. It was like finding a new Starrett tool on the sidewalk in perfect condition. It just put a smile on my face.
Talk to you soon.
Tom
He does it wrong way. He should adjusts depth at compound slide rather than at cross slide.
Not necessarily. i don't see any reason to use the old fashioned way of setting the compound at 29 degrees and then letting one side of the tool burnish rather than cut. Might be OK with HSS tooling but most inserts don't do their best work with a very small depth of cut. That's what results when using the compound to advance. The left hand side of the tool would cut but the right hand side would burnish & heat. What do you gain by using the compound?
Clever, really good idea for machines that don''t have a foot brake (probably not the proper term for it)
And, for anyone doing metric threads- due to backlash, don't forget to pull your tool out before reversing! Quite a few winners I've seen forget to do that, not realizing how much slop some machines have
Hi Jay,
Thanks for the comment.
Cheers,
Tom
I'm new to actually doing any machining. I've been studying for a couple years but just got a lathe this spring. I've only done a few threading operations whatsoever. As I've read about going metric threading on my old Logan 10" it always seemed to me like this method you show should be perfectly doable. But everything I read said that you MUST leave the half nut engaged to do metric threading on an inch leadscrew. Thank you for confirming my "naïve" suspicion. :)
Hi Jon,
This is why this technique is so important. It really shows that the must leave half nuts engaged is not needed with a little care. Thanks for the comment.
Cheers,
Tom
I like it, thanks Tom for the great demo.
Nice demo Tom. Always learning!
So much to consider for a seemingly simple little plug:)
Keep in mind that there is a 3mm radius on the top flange of the transformer, so you can stop the thread 1mm short of the shoulder if you like..
You are getting me very excited now!
Hey Nick,
Fenner had the million dollar steady rest series. Now I have the 500Kb (kilo buck) brass plug. Everybody is going to really want to see where this goes.
Cheers,
Tom
Thanks a lot for this! Great tip!
Fantastic technique, just tried it ....just awesome...thank's for sharing. Would be great if you could show an internal thread with this technique.
That's one for the collection for sure! Thanks for putting it in living color...CZcams is great. My eye caught something during the video that I wondered if you would give us a better look at? That is the rack for your quick change tool holders.
Thanks!
Dru
Hey Dru,
I did a segment in one of the meatloafs on the tool rack. Search tool rack or toolholder rack and see if it catches it.
Cheers,
Tom
Good tip! It also seems that after you pullout and shut down the lathe, you could manually move the carriage until the thread dial lines up, engage the half-nut, then go in reverse. Should be the same. I'll have to check it out. It may be easier for those with a fine lead screw.
That is a very nice strategy!
Thanks for sharing that technique Tom. Just recently I was faced with the same scenario of metric threading up to a shoulder. To cut back on the stress factor I set up a micro switch mounted on a magnet on the lathe bed that would shut down the lathe motor just in time to allow the tool to coast up to the shoulder. Worked great but this would have saved me some screwing around.
Hey Chris,
I feel the same way. Somebody mentioned you can hand turn the spindle with the half nut engaged if the thread is in easy material and fine enough.
Cheers,
Tom
If the motor is 3 phase and the gearbox is industrial strength you can get very good repeatability from a micro switch by using "plug reversing", which is basically the same idea as the ancient dodge of stopping a steam engine by throwing it straight into reverse. Plug reversing used to be in common use on turret lathes, at least in the UK, and the motors were often fitted with a "zero speed sensing" switch, which would turn the power off at the moment rotation ceased, effectively using the motor as a very powerful brake.
However for threading this switch is not necessary, as you actually want to reverse the spindle rotation to get back for the next pass.
The concept works particularly well with a swingup toolholder, a modern idea based on an ancient one (the clapper box used on shapers and planers) which makes it unnecessary to withdraw the tool for the return to the next pass. It makes it possible to thread at CNC spindle speeds, at least if you have a VFD (where decel and accel can be set to make reversing a bit less instant, hence easier on the gearbox).
It can even eliminate the need for a thread relief groove, at least when using HSS (except in very hard materials)
If this idea had been commonly known a hundred years ago, the need for such things as threading dials, single tooth dog clutches, rapid retract toolposts and crosslides, ball-stop crossfeed, snaptap threading devices etc etc, would have been much more limited -- mainly I would guess being needed for internal single point threadcutting, where a swingup toolholder is impracticable, or for hobby lathes with single phase motors or lightly built gearboxes.
Conrad Hoffman is a pretty good guy, I have had a couple of conversations with him over at PM, didnt know he had this up though, thanks for pointing it out and the great demo.
Stan
Hi Stan,
What is his handle over on PM? I have seen his article on thread tool honing before but must have missed this gem.
Cheers,
Tom
Oddly enough .. Conrad Hoffman is his user name
Love the new intro and I enjoyed the tip. I hope I remember this when I buy my lathe. :)
Hey Wyatt,
I already forgot. I'll probably have to watch my own video again with that guy that says uhhhh all the time.
Cheers,
Tom
Nice video. I also enjoyed your book very much, Tom.
Hi Shobar,
Thanks for the nice comment and support.
Cheers,
Tom
Great video! Nice trick. I know someone who would have loved to know this before he messed up two parts that took quite a bit of work.
That is so stupid simple it's pathetic. Why did it take so many years for someone to think of this, and explain it so much earlier? Wonderful video, as always.
Your a clever guy!! you know that? Nobody thought at this before. Salute from England from a Transilvanian guy :))))
Hi Gigi,
Thanks for the comment.
Cheers,
Tom
Great Video, Like Lee below I am new to machining. I use PVC pipe to practice on. This technique was perfect first time out. Keep up the videos
you can do the same idea but still manually move the carriage back if you are using a carriage stop. i do this on inside threading for when i cant have a relief cut. like on the inside of a pressure vessel. ( relief cut can make wall thickness to small) you unlock the halfnut then shut off the machine, then roll back the carriage to the start position then start the machine in revers without the halfnut engaged until it lines up with number you started with on the threading gauge. set cutter to depth reengage halfnut then start machine.
Thanks for sharing this trick and thank you CZcams.
fantastic tip! im a novice and im trying threading for the first time as soon as my inserts show up.
Hi Jason,
Thanks for the comment.
Cheers,
Tom
Tom that is a really cool trick indeed.
Hey Bill,
I was stoked when I tried it. Its a keeper.
Cheers,
Tom
Tom, that is a fantastic trick! Honestly I have never cut a metric thread with a lathe, however since I have seen you talk about it in some of your videos I feel ready to try one. In the shop at school I only have one lathe (a Nardini) capable of metric threads. My primary lathe at home is a 20"x36" American Tool Works circa 1903 and I am fairly certain none of these were ever built to do metric threads.
Hey Mike,
Well all I can say is you will cut one eventually. Wow 20 x 36 lathe. That's almost tuna can proportions.
Cheers,
Tom
I appreciate the meaningful titles
great video thank you!
Hey Tom, love the guide on how to do this im trying this technique at the moment on my new lathe.
just a quick question ive reading conflicting how to's on threading, most are saying that you should compound feed instead of crossfeed? but in this vid you crossfeed the tool into the job
ive set my compound to 30degs as per my 60deg thread but when i compound feed it just keeps laying over the back thread?
im trying to make the same 18x1 thread as your doing
Thanks for any input
Cheers Troy
Used this today, worked like a charm. Thank you. :)
Al
Nice and thanks for sharing.
Thanks for this idea.
This will come in very handy if I ever end up with a lathe capable of cutting metric threads, or even one capable of reverse without flipping wires for that matter! lol Thanks for the great educational demonstration.
Hey Brian,
Just turn your lathe around 180 degrees, instant reverse. Its all in the observer.
Cheers,
Tom
At 9000lbs of lathe I think I will just stand on the other side. :-) That should work too. lol
Thanks for that Tom, getting the timing down will require some practice but that is a great idea. Gotta go make some chips now!
Hey Joe,
I practiced a little before I shot the video. I wanted to get the moves down.
Cheers,
Tom
depends on slack in screw and half nut apron etc. you can also engage every thing and use jog circuit on spindle. jog stops faster than spindle drive
I really enjoyed this video demonstration. Thank you. But what did you set your machine to? The only thing I got was 200 RPM.
great tip ty for sharing it.
Tom, thanks for conveying the cool technique. I think I'm starting to understand this threading stuff (will have to wait until I have a lathe to be sure though).
I understand the 30 degree thing vs the straight in form tool concept, but it occurs to me that using both compound and cross slide feed has an advantage even when going straight in...it reduces reliance on memory. In another video I've seen (maybe one of Mrpete222?) the cross slide was always used to back out of the thread, and always 1/2 or 1 full turn of the handle...so it was always 1/2or 1 full turn back in. The compound was used to control the cutting depth adjustment...and only ever advanced as the thread was cut, so no need to remember anything...just move in another increment and go.
Seems to me you could combine that with another method I've seen and set the compound initially to the negative of the depth you want and advance back to zero as you go. So as you are threading it's just one turn out on cross, move back to start, one turn in on cross, turn compound in a bit, if it gets to zero, it's the last pass. No math needed as you go, and no need to remember any numbers.
What do you think?
-- Mike
Hi Mike,
Its certainly easier to remember where you are when you use the compound or top slide as our viewers from the UK call it. Both methods work radial and angular. Your suggestion would work fine. The only issue I see is the numbers are weird. For example the dial reads zero to say two hundred when turned clockwise. If you unwind it you are starting at say one hundred forty five. As you advance toward zero the numbers don't have any direct reading correlation to the amount of slide advancement. So in this case I say old school rules.
Cheers,
Tom
Very good video Tom
Thanks for the new trick :))
Manny
by the way I ended up buying a Wilton 1440 gap bed lathe which is basically a Jet lathe model TL1440 hope its an ok lathe
I too am having much difficulty cutting a metric thread on a standardized lathe. Standard threads L and R no problem. And this is a great trick for keeping that position on the lead screw. I understand why you would need to do this when cutting a metric thread just fine. But what I don't understand is how to set up the change gears that are made for standard size threads to cut for example a 1.5mm thread? How do you get the right gear ratio? maybe you can explain that to us Tom. Thank you for making your videos and putting them out there.
That's a great technique.
Wow, that's great! Isn't CZcams awesome!
Thanks for posting this up Tom
Regards, Bill
Hi Tom if you get this. I would like to know we’re I could get one of the Starret posters. Thank ya
LOL.....well I'll be, now that is a really clever method of stopping the saddle travel when you get to the end of the thread and have to run up to a shoulder etc.
I don't have a threading dial on my old 1930 Colchester Bantam lathe but now I think I can use one even for Metric which I do mostly now......been using the manual spindle wind back method for years.
This is the never too old to learn new tricks scenario we are all in to if we want to get clever.
As you demonstrate, on fine threads in relatively soft material, you can advance the tool with the cross slide. But there's zero reason to have the compound set @ ~30* if not using the compound to advance the tool. A coarser thread in some 4140, not so much.
As far as the temporarily disengaging the half nut. I've become aware of this. Great tip.
Any tips on cutting internal metric threads in a blind hole? I would like to cut away from the chuck for speed and safety. (I have 300 parts to do). I thought about setting up a dial indicator to zero when I'm at the bottom of the hole and engaging the half nut on the same mark on the thread dial. Please tell me a better way if you can think of it. Thanks
Hi Tom,
Sorry to dredge this up from the distant past!
I wanted to ask how much effect would the backlash in the gear train from spindle to leadscrew have on this technique? Presumably there’s a point where it could allow you to catch the thread next to the one you want but still read as 1 on the threading dial? Would going in reverse past the 1 and then running the lathe forward again to engage at the 1 eliminate this (obviously you’d have to then reverse the carriage back to your start point as well)?
Thanks!
Abom, do you have a sample video of the through threading?
And I hope there is a way to cut inch threads with a metric lead screw, 'cause that's probably what I'll have to do.
Thanks man that's awesome appreciate it
Wish I had seen this video a couple of months ago.I had to cut an internal 38 X 1.25 mm thread in a blind hole for an adapter I was making for a hydraulic puller.Great stuff. Mucky Mel
Hi Tom , Thanks for your nice vid , in our shop we dont use chasing dial at all , just all time engaging and reversing at the and of the pass with out stopping the machine. (metric) i hope you understand what i'm saying .
Hi Nacer,
I do understand. For us metric handicaps we have to use special tricks to get it done. Thanks for the comment.
Cheers,
Tom
I'll be dipped in doo-doo if that's not a trick worth knowing! Thanks Tom.
Hey John,
That's one way to spin it.
Cheers,
Tom
How does this help with threading to a shoulder if you can't move carriage in between the threading passes?
very good video, thanks ....
That is a very usefull trick! Thanks for sharing. Will use it the next time threading to a shoulder.
Cool stuff!
Hello Tom
Would you please explain how you set up your gearbox to get a metric thread out of an inch lead screw?
Thanks
Bill
Video 200 !!! great vid !