Thread dial question

[john mullen]

I tried my first threading today. 1.500 8 tpi. I was making a holder for a 3" 3 jaw chuck to fit to a 5c collet for my spin index. what a nightmare, my 10x 24 jet lathe has a feed index wheel and I started the thread on the number 2 and when I came back for the second cut I also started on the number 2 but the threads were not the same and it made new thread pattern . it didn't repeat the thread pattern . then I measured the travel for 1 turn on the 8marked wheel and the carrage only moved 3" not 4" as I expected.
Anyone had any experience on the jet 10x24 threading. I need skoolin... John

 

[JimDawson]

John, it kind of sounds like your gear train is not set up correctly for threading 8TPI. I would expect the threads to repeat when you hit the same number on the threading dial. Not sure what you mean by ''then I measured the travel for 1 turn on the 8marked wheel and the carrage only moved 3" not 4" as I expected. '', if you are talking about the threading dial (the 8marked wheel?). That movement/revolution would depend on the pitch of the lead screw and the pitch diameter of the mating gear.

Sorry I am not being very clear here, maybe you could post a couple of pictures of your setup and I'll be better able to help you.

 

[Don B]

That's very odd, as Jim says sounds like something isn't set up right, for an even number like that you should be able to drop it in on any number but most defiantly should work on the same number, is there any chance that the compound was moved?

 

[12bolts]

John,
What is the thread pitch of your leadscrew?

Cheers Phil

 

[Terrywerm]

Chances are that your lathe has an 8 pitch lead screw, or 8 threads per inch. If this is the case, you should be able to engage the half nut lever anywhere and still end up on your first thread, since you are attempting the same pitch thread as the lead screw. If your lead screw is in fact 8 threads per inch, then I agree with the others that either the gearing between the spindle and the quick change gear box is incorrect, or your quick change gearbox is not set correctly.

I must apologize that I cannot offer any advice based on the lathe that you have, as I do not have the same lathe as you, but most of them are so similar that it is almost uncanny.

 

[john mullen]

John,
What is the thread pitch of your leadscrew?

Cheers Phil

the lead screw pitch is 8 tpi x 5/8 dia.

- - - Updated - - -

hear are photos of my lathe... my settings were lever b and 1 on the gear box
by the way the photo of the gear box was not where it was set for the threading , it is where I set it when running the power feed when turning

 

[john mullen]

I was reading the lathe manual and looking at the thread charts it shows a set up of leavers b and 1 for 8 tpi however it also shows a chart for Diametrical pitch threads as lever a and 1 for 8 tpi . The thread I was trying to match is the spindle thread from my old craftsman 10' that has a 1.500 x 8tpi spindle thread and I now wonder if this is a diametrical thread pattern ??? just something I need to find out before I attempt a do over

 

[chips&more]

I’m not sure about the amount of carriage travel with one revolution of the threading dial? But, it definitely sounds like something moved on you. If you always start/engage on the same thread dial number, it will always cut on the same thread cut. Or maybe you did not engage the half nuts/threading lever all the way, that will give you the problem you are having...Good Luck.

 

[Tozguy]

Wouldn't it be a bit$h if the thread dial screws were loose and it was skipping on the leadscrew.

 

[Don B]

I was reading the lathe manual and looking at the thread charts it shows a set up of leavers b and 1 for 8 tpi however it also shows a chart for Diametrical pitch threads as lever a and 1 for 8 tpi . The thread I was trying to match is the spindle thread from my old craftsman 10' that has a 1.500 x 8tpi spindle thread and I now wonder if this is a diametrical thread pattern ??? just something I need to find out before I attempt a do over

B 1 looks right is there a gear train form the spindle to the QC gear box that could have an improper gear installed in the wrong position..?
Put it in B 1 and engage the split nut, put an indicator on the saddle, rotate a little to remove backlash, then rotate the spindle one turn an see what you get (all by hand)