buggered spindle threads

[bowlman]

Here is a photo of the outboard spindle of my circa 1982 General 260. The Oneway vacuum rotary adapter came loose and rattled around on the spindle before I was able to ut down the lathe. Of course, with a blank on the in board side, the spindle kept right on rotating. You can see the results. Compare the flattened top threads with the knife edge thread right next to the green headstock.

So I'm screwed right? Option 1: take the headstock apart (an all day job) take the spindle to a machinist and have them restore the 1 1/8 x 8 left hand threads. Big $$$$ ... or

Option 2: take the spindle out, order a new one from General Interational, and hope that 1) it fits and 2) thy still make that particular spindle ... bigger bucks... or

Option 3: Buy a new American Beauty (good reason to buy one, right?) even bigger $$$$

Option 4: find a way to do it myself. can I find a tap and die large enough to do it and do it with the spindle in place? Maybe I had a hardened left hand nut I could thread it on and restore the threads.

But wait a minute! I DO have a left hand nut ... its called the hand wheel. And yes, it is harder than the spindle. So, find the handwheel (20 minutes of searching) use my extra large channel locks, and several minutes later, all the threads are now knife edged once again. damn, I'm just brilliant today. Tomorrow is Tuesday ... that's my day to be a dumb***.

 

[Bill Boehme]

Option 3, obviously. 😀 It only hurts once to buy quality.

Even though the threads are not pretty, it looks as though there is still sufficient thread depth for chucks and faceplates to solidly hold. I should mention that alignment is not provided by the threads, but by the flat registration face at the base of the threads that mates with the registration face on the chuck or faceplate. Threads are not accurate enough for controlling alignment. Standard threads have about a 50% engagement. Even tapered threads can't provide accurate alignment -- the angular and radial errors will vary with the amounts of tightening torque. You might consider what was done in another recent thread where a threaded adapter was used to change the spindle diameter. You might need to go to 1½" since it doesn't seem likely that you could go from 1⅛" to 1¼" diameter.

What could a machine shop do? Possibly machine the spindle down and then press a bushing on that could be threaded. However the Morse taper socket in the spindle would put a restriction on how much machining could be done. It is also possible that the MT socket would have to be reworked after such an operation.

 

[Tom Hamilton]

Option 3: Buy a new American Beauty (good reason to buy one, right?) even bigger $$$$

I see no other options. 😀

Happy turning
Tom

 

[Hu Lowery]

I think you messed up!

Here is a photo of the outboard spindle of my circa 1982 General 260. The Oneway vacuum rotary adapter came loose and rattled around on the spindle before I was able to ut down the lathe. Of course, with a blank on the in board side, the spindle kept right on rotating. You can see the results. Compare the flattened top threads with the knife edge thread right next to the green headstock.

So I'm screwed right? Option 1: take the headstock apart (an all day job) take the spindle to a machinist and have them restore the 1 1/8 x 8 left hand threads. Big $$$$ ... or

Option 2: take the spindle out, order a new one from General Interational, and hope that 1) it fits and 2) thy still make that particular spindle ... bigger bucks... or

Option 3: Buy a new American Beauty (good reason to buy one, right?) even bigger $$$$

Option 4: find a way to do it myself. can I find a tap and die large enough to do it and do it with the spindle in place? Maybe I had a hardened left hand nut I could thread it on and restore the threads.

But wait a minute! I DO have a left hand nut ... its called the hand wheel. And yes, it is harder than the spindle. So, find the handwheel (20 minutes of searching) use my extra large channel locks, and several minutes later, all the threads are now knife edged once again. damn, I'm just brilliant today. Tomorrow is Tuesday ... that's my day to be a dumb***.

You had a perfectly valid reason to go out and buy the American Beauty and you went and fixed the problem instead!

Sounds like you are in business this time but for future reference there are some square bar thread chasers. Fairly inexpensive and I think you get eight different tooth counts per bar. I'm pretty sure they work equally well on right and left hand threads. I was pretty skeptical until I tried one, it worked well.

Hu

 

[Bill Boehme]

You had a perfectly valid reason to go out and buy the American Beauty and you went and fixed the problem instead!

Sounds like you are in business this time but for future reference there are some square bar thread chasers. Fairly inexpensive and I think you get eight different tooth counts per bar. I'm pretty sure they work equally well on right and left hand threads. I was pretty skeptical until I tried one, it worked well.

Hu

Are you talking about this or something else?





I believe that the threads are slightly inclined. Their "complete" description neglects to give the thread pitches.

I have never seen external helicoils, but wonder if they exist.

 

[Hu Lowery]

This was a bar

Are you talking about this or something else?


View attachment 6082


I believe that the threads are slightly inclined. Their "complete" description neglects to give the thread pitches.

I have never seen external helicoils, but wonder if they exist.

Bill,

Never seen external helicoil type repair kits either, no idea if they exist.

The thread chaser was a square bar. A little over a half inch per side best I remember and about ten inches long. Each side had a different tooth count on each end that went most of the way to the middle of the bar. Had to dig awhile, they actually call it a thread repair file. You may need to click on a larger picture to tell but they are square and the teeth run so that you can stroke the file lengthways across the bad teeth. Once started you rotate the shaft or whatever and keep stroking with the file. Cleaned up some nasty threads for me that I couldn't replace without spending a lot of dollars and did it quite fast. Works on threads so damaged it is hard to start a die on since you can start clean up any place on the threads and work your way from good to damaged thread areas.

Hu

http://www.amazon.com/Nicholson-Thr...1373516127&sr=8-1&keywords=thread+repair+file

 

[Bill Boehme]

I have seen those thread files, but never really paid attention to what they were meant to do.

I have a different kind of tool that is around 80 to 100 years old or more. My dad gave it to me and he got it from someone much older than he was at the time. It is a hinged two piece die that will allow you to put a given thread pitch on a range of rod diameters. You could even use it to put threads in the middle of a smooth rod, but I don't know how you would get a nut on it. 😀

 

[Hu Lowery]

old tools

I have seen those thread files, but never really paid attention to what they were meant to do.

I have a different kind of tool that is around 80 to 100 years old or more. My dad gave it to me and he got it from someone much older than he was at the time. It is a hinged two piece die that will allow you to put a given thread pitch on a range of rod diameters. You could even use it to put threads in the middle of a smooth rod, but I don't know how you would get a nut on it. 😀

Bill,

I run across an old tool every now and then that it seems the only reason they quit making them is that they figured out people would pay more for something else! Something I think is still available but you rarely see is the split die. They have a slot and an adjustment screw and you can fit the threaded shaft to whatever you are threading it into with whatever contact you want. Now all I usually see are very expensive dies if you want more than typical contact.

I think what Dick needs now is a thread buggering tool so he can go buy that Robust!

Hu

 

[Bill Boehme]

... I think what Dick needs now is a thread buggering tool so he can go buy that Robust!

I recommend that he thread a RH nut onto those LH threads. Next step, give Brent English a call.

 

[Hu Lowery]

should do it!

I recommend that he thread a RH nut onto those LH threads. Next step, give Brent English a call.

That'll work!! 😀😀😀