Single Point Threading First Time

[MontanaLon]

You are over thinking it. Just study how, then do some dry runs with the tool not engaged with the work (just clear of the work) until you get the muscle memory and are confident, and then cut metal.

This, it takes practice. You will find that even with cat like reflexes, hitting the numbers takes some advanced skills. And that will vary depending on the thread pitch and of course the speed of the machine. Whatever is making the dial move faster makes it harder.

 

[Bob Korves]

This, it takes practice. You will find that even with cat like reflexes, hitting the numbers takes some advanced skills. And that will vary depending on the thread pitch and of course the speed of the machine. Whatever is making the dial move faster makes it harder.

Someone already mentioned above that if you are starting from the end of the work and have plenty of clearance there, just start farther off the work for engaging the half nuts. If something goes wrong, you will have time to stop the spindle or disengage the half nuts. I rarely start cutting threads close to the work unless I have to, it just does not save much time, and can ruin the part, which wastes lots of time...

 

[ThinWoodsman]

The You Tube is by Joe Pieczynski where you turn the threading tool upside down and run lathe in reverse,and you don't adjust the compound slide you only adjust the cross slide.OK this is fantastic,but I'm a newbie and this seems to easy so I was wondering if other have tried his method of threading.Did you like or dislike threading in reverse?Pro/Cons if there is any?

I tried that technique after watching the video. Quite liked it - set the lathe at a low speed, put a carriage stop where the thread starts, and then just let it run off the end of the bolt. I had the work in a collet. The spindle on my Logan lathe is threaded, so if holding work in the chuck I'd be too scared of the chuck coming off to try it.

 

[Larry42]

I've gone to Joe's method. I find it easier. I can thread @ a higher speed. I can very easily engage the half nuts at the correct position. Again by following Joe's suggestion of putting a slight pressure on the lever slightly ahead of time. It will then very easily drop in at the correct position. No need to do the slam in method I've seen others use. It is very easy to position the tool at the start point, much easier than trying to disengage in a very narrow relief. As for the use of the compound at more or less 30* it just complicates the process and I can't see that anything is gained. On the other hand I can see a problem when an exact 30* is not dialed in. Which is most likely the case. If the back side of the tool is not engaged enough to actually cut it will result in a rubbing/burnishing action. Not desirable for several reasons. On the other hand if it is engaged enough to be cutting then you are doing the same as plunge cutting. As for liking to see the tool cutting, what do you do when cutting an internal thread? Each to his own. But you may make your life easier by just carefully watching Joe's video(s.)

 

[Bob Korves]

To cut threads from a shoulder off the work, I put the tool on the back of the work, with the normal top side of the tool facing up, as usual. Then I run the spindle in reverse to make the cut until it runs off the work. It is simple, looks normal, you can see what is happening, it just works. But, I do not have a threaded chuck/spindle.

 

[Martin W]

It only hurts because it is true. But it was said entirely in jest. But unless you are left handed, if tomorrow you saw no one who was left handed ever again, you would never notice. On the flip side, if everyone you ran into was left handed, you would absolutely notice. Unless of course you are of the type to run the carriage into the tailstock,

???????

 

[darkzero]

As for liking to see the tool cutting, what do you do when cutting an internal thread?

For internal threading I mount my tool upside to cut on the back side, still right to left though. I do use the compound for threading so this method allows me to use the same compound position as I use for external thread. Tool is upside so yes I can't actually see the cut but at least it is somewhat visible rather than being completely blind. Not that I really care, more it's the compound position that I like.

 

[hman]

+1 on Mal's caution about threading in reverse when you have a screw-on chuck. But with suitable cautions, it should be OK.

On the other hand ... back in 2017 I speculated that adding a switch to a lathe stop might be useful if you have a VFD with a braking resistor:
https://www.hobby-machinist.com/threads/lathe-threading-auto-stop.25014/page-2#post-460048 (Post #32)
I recently got a small CNC mill, designed the switch enclosure, and made the stop. See post #7 att:

Fusion 360 G-code bugs(?)

I recently bought a vintage DynaMyte DM2400 mill, converted to Centroid CNC, as a way of "taking the plunge" into CNC. I also bought Fusion 360, because my previous CAD software (CREO Elements Direct, free/restricted version) couldn't output any appropriate format. I've finally learned enough...

www.hobby-machinist.com

Here's a photo of the completed stop.


I tested it a couple days ago, and it does a great job of stopping the chuck consistently. 100 RPM, 8 TPI, 10 stops, all within ~½" on the circumference of the 8" chuck, or about 6º. The "X" on the chuck shows where the switch clicks, so the spindle repeatably stops within about ¼ turn at 100 RPM. At 8TPI, that's about 1/64". I'll be doing a final check, threading to a shoulder (with relief groove), within the next few days..

 

[Jubil]

I use the Joe Pie method and like it a lot. It's just easier and less stressful for me (key words "for me"). But I think you should get some scrap and learn both ways. Just my $0.02 worth.

Chuck

 

[Technical Ted]

I've never tried the Joe Pie method. I learned the way suggested in South Bend's book "How to Run a Lathe" years ago and have always used that method. Never had a reason to try a different way. If I'm threading up to a shoulder I will just slow things down. If I have a hard time seeing the relief groove at the end of the thread (because of chips and/or cutting oil) I'll put a dial indicator on the way so that it contacts the carriage as it approaches and I stop it when it hits "0". You can get good timing watching the needle move as it approaches "0".

Also, I always thread with my cross feed lever at the 9:00 position. When I get to the relief groove I know I have to push the handle down to get out. This also helps if I run into trouble while cutting the thread... just push down to get out! Threading internal? Set the handle at 3:00 and push down to get out of trouble! You don't have time to think and having an automatic move helps when things get nasty.

I also like using a hard thread stop. I made one for both my 15" and 13" SB lathes. It's nice to have a positive stop to return to each time between passes.

Use whatever method you are comfortable with. Don't be afraid of slowing things way down. You don't get extra credit for going fast! Take your time and you'll be fine.

Ted