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Knowledge You Can Build On — Est. 1998

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A discovery about lathe alignment

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A discovery about lathe alignment

#1

A discovery about lathe alignment

John K Jordan

I discovered something yesterday. It appears to me that two supposedly identical lathes may not have interchangeable headstocks/tailstocks.

I have two Jet 1642 lathes in my shop. A few weeks ago a VFD failed and while it was down I moved the headstock from the second lathe over to my primary lathe so I could keep playing.

When turning some small finials with tailstock support I ran into vibration problems so I checked the alignment between headstock and tailstock. It was off by almost 1/16"!! Ack.

I tried jacking on the lathe legs but it would not get it close enough. Finally I swapped tailstocks with the other lathe and alignment was perfect.

Are these things made in aligned pairs? Are the tolerances so bad that someone at the factory has to try 15 tailstocks until they find one that is close? Perhaps a change in setup at the factory prevents interchange of parts from a different production run.

Maybe everyone kneew about this but me! One more thing to think about.

JKJ

Re: A discovery about lathe alignment

#2

Re: A discovery about lathe alignment

Dave Paine

I did not know this, but I am not surprised. I did not appreciate how bad the tolerances are in my wood lathe until I purchased a metal lathe.

I am wondering if the headstock/tailstock are machined to fit a particular lathe bed. This could result in slight differences in centreline to lathe bed dimension.

Perhaps the issue was lateral alignment difference. I can imagine how easily this would change from one lathe to another assuming the headstock does not have alignment pin which is likely.

Re: A discovery about lathe alignment

#3

Re: A discovery about lathe alignment

Dick Coers

Just can't imagine anything in this price point is machined in matching pairs. Maybe they have a department where the cheap labor can match them, but even doubt that. I would suspect that everything done in one production run would match, change tooling and maybe not a dead match the next time. Quite the mystery!

Re: A discovery about lathe alignment

#4

Re: A discovery about lathe alignment

Jim K from Trappe, PA

I found a similar issue with some chucks. I have two stronghold chucks, and the keys are different. They were both bought used, and are of different ages, so I guess they made some engineering changes along the way.

Re: A discovery about lathe alignment

#5

Re: A discovery about lathe alignment

ben d.

I changed out the tailstock on my 1442 and didn't really have any alignment problem but the one thing that I do is to unlock the headstock and run the tailstock up to it remove the center in the headstock and screw the locked tailstock live center into the headstock and push it on the ways just a bit then lock it down then turn the locking screw which had taken care of any misalignment that I have had.

ben d.

Re: A discovery about lathe alignment

#6

Re: A discovery about lathe alignment

John K Jordan

That sounds like a good technique. This pair was so far out and with so little slop nothing less than a file or milling machine (or maybe a big sledge hammer) would have helped!