Shelton lathe run out

[jjtjr]

I have a 10" Shelton lathe. I seen to have run out but don't know where is coming from. When I make a long cut say 6" using the collects and center on the tail stock. Then make a pass the cut near the tail stock is greater then at the collects. To set the tail stock on center I used a test bar about 2' long and dialed it so the tail stock had no taper. But still got a taper when making cuts. Do I have bad bearings in my head stock or is my ways worn. Any info would help.

 

[Tom Griffin]

First of all if you are using a center in the tailstock you should be using a center in the headstock, not a collet. If there is any misalignment of the tailstock, constraining the part on one end will cause it to bow. Try doing the same thing over again using two centers and a lathe dog to drive the part and see if you get the same results. Also make sure your tool is properly ground and on center. Not enough clearance on the tool or setting it above center can cause the problems you describe.

Tom

 

[GK1918]

second reply first one got dumped. My gut feeling still points to the tailstock a real pain in my book.
If sombody ever dropped a test bar its junk and then my bunch of dial ind. dont read the same. I think
the best is Mr Petes vidio the South Bend method that is fail safe. If you havent watched its all made
from the junk box. Its about 1" round about a foot face and center drill both ends. Get two pieces of
alum or brass thats say 2"round by 1"fat. thats bored to the 1'' round stock, now press or Tubal used
lock tight to the ends of the bar. Your going to drive it with a dog in both dead centers. With power
feed take a light cut right to left, just let it run the bed by itself do this a couple times until both ends,
the alum or brass did get turned. Now mic. both. the error is always on the tailstock end. So say the
headstock end reads 2.000 even and the tailstock reads 1.950 so tweek the tailstock, I would go less
that half the error. Now I would just touch off the 1.950 move over to the headstock and turn that to
1.950 then start over and turn a slight cut across the board then mic. both should be getting closer,
repete till both ends are the same one or two thou good enough. Again tweeking tailstocks is a time
pain one twitch or hiccup and all is for not. Good thing all is made from junk and you can see whats
going on. Also remember its done between centers, when done the machine is now on line. Next is
the issue of a worn tailstock (two low) pinch a razor blade between centers that will show up quick,
if off , got to be shimmed. I dont think its ways or headstock unless its past dead. I do know tail-
stock will wear before ways do and have to be tweeked. Us old timers just have a knack for good
results on worn machines. Im not good with words hope it helps oh , once you make this thing
its now a tool for the future for the draw.. sam