Single Point Threading Issue - might be gearing?

Mine: a Yugo cobbled together with a leftover wheel off of a busted up measuring wheel that looks to be a wart on the lathe...

Mike's: a Rolls Royce piece that actually looks to be part of the machine.
:grin:
Titanium Knurler said:
WobblyHand, I attached a handwheel to my PM1236-T by attaching a solid wheel bored centrally to the same size as my spindle bore using a collar attached by an interference fit. This setup allows you to maintain your spindle bore for longer pieces and the solid wheel helps prevent you from getting entangled in the wheel spokes. It is removable but it pretty much stays on the machine. I use it all the time, especially when doing things like centering a piece in the 4JC. I bet a similar setup will work for your project. It amazing how one simple project leads to others. I have a pretty detailed description of it here on H-M.


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MrWhoopee said:
I would never try to discourage someone from trying new things or improving their skills.

However, if the object is to produce that little pin from O-1, I suggest simply using a die and (if necessary) making a very narrow undercut at the shoulder. It is difficult enough to get a decent surface finish threading O-1 at the appropriate cutting speeds. For this diameter, I calculate a turning speed of 1000 rpm and threading about half that. Slowing it down enough to compensate for your lack of experience is a recipe for extreme frustration. Feel free to try single-pointing for the practice, but be prepared to use a die to get the job done. I've done a lot of single-point threading, and I would use a die.

Learning to thread is much easier on larger parts with better machinability where the rpm's are lower and it's easier to get a finish. Once you've worked out the moves and timing you can progress to more challenging jobs.

You have to learn to walk before you can run.
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At some point, I'd like to make that little pin. I thought I'd use the pin as an excuse to learn SPT. Managed to do a couple of decent cuts, but my confidence is still low in stopping the threading fast enough. I get it right most of the time, but not always. The idea of using a stop and a dial indicator is interesting. Threading looks like it's a combination of eye/hand coordination, muscle memory and just practice, which I'm willing to do.

For the heck of it, I'll try using a die as well. That doesn't mean I'll abandon trying SPT to make the part. It's an interesting and compact problem.

Walking! Hah! I'm still working on the crawling part right now.
 
If you're planning to use tool steel like O-1, you are better off screw cutting the threads.

A die might work but getting the threads close to a shoulder probably won't happen so you might want to cut a thread relief first. If you try it, use a good, sharp HSS die and start on the side where the threads taper. Once the die has cut a few threads, flip the die over to get as close to the shoulder as you can.
 
WobblyHand said:
Threading looks like it's a combination of eye/hand coordination, muscle memory and just practice, which I'm willing to do.
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It is definitely all of that. I first learned to single-point in 1979. I still get that nervous feeling in the pit of my stomach on the first engagement of the half-nuts, especially when threading up to a shoulder. (I'm getting old, are my reflexes still up to it?) Once I've made 2 or 3 passes it subsides.
 
middle.road said:
Mine: a Yugo cobbled together with a leftover wheel off of a busted up measuring wheel that looks to be a wart on the lathe...

Mike's: a Rolls Royce piece that actually looks to be part of the machine.
:grin:
Click to expand...

I bet yours works just fine! I don’t know about you but I use mine all the time. I think a handwheel should be standard equipment or at least on option on a lathe.
 
darkzero said:
But if threading a very coarse pitch the thread dial will be moving pretty fast. There is no room for error engaging the half nut on a specific mark when needed.
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No kidding. My first for real threading was a 5tpi inside thread in a blind hole. Perfect for a beginner, right? I missed my mark more than once. Even though I was threading 6061 I still clobbered my home made cutter more than once.

Looking back, that hole didn’t really need to be blind and I should have just threaded it toward the headstock. Live and learn....
 
I think I'll make the spindle crank. Just ordered some stock for the spindle insert. I have stuff for the handle.

For anyone with a SIEG mini-lathe, LMS has the spindle crank for sale. Not sure the crank will solve my problem, but hey, it's a tool I can make. The first of many...

I will have to remember to unplug the lathe whenever it's attached. A spindle crank looks like a real arm breaker.
 
I made one for my mini lathe a couple of years ago. I used a chromed wheel from McMaster-Carr and machined the rest out of 4130. I think the angle of the cut was 37°. I think I posted it in the what did you do today thread. Works great for threading.

Roy

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