Craftsman 101.07381 headstock alignment

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fast204

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Hello all. I have an alignment question. My 12" craftsman lathe had a babbit bearing headstock, the bearings were shot so I replaced it with a timken roller unit. I have found that when turning ods I have a .002" taper consistently. The larger diameter being on the tailstock end of the work piece. I have wear on the ways but have tested at different spots with the same result.
Is it safe to assume the headstock needs to be trued? How do I test this? And can it be done?

All work was done without the tailstock.
 
I have the same problem on my little 6" and like you I have swapped heads also. I don't know if the factory hand-fitted each head to bed but I suspect it may be a batch issue.
Only way to correct it is to carefully remove material on the headstock boss that engages with the bed such that the headstock will rotate toward you (clockwise if you are looking down on it) a tiny amount to bring it back to perfect alignment, the resulting gap on the diagonal corners would have to be filled with epoxy or similar. How much patience you got? :)
Mark S.
 
I have a good bit of patience and some time. I was hoping it might be a matter of loosening the 3 bolts from headstock to bed and torqueing them in a different pattern but I'm open to explore the option.
 
A easy quick check , mount your face plate on the spindle , put a indicator in the tool post and drag it along the face plate .
 
If I can find the face plate I will try that. Would it work the same indicating the left and right face of my 3 jaw chuck??
 
.002" taper over what distance? Without the stock being supported by a tailstock center, deflection caused by tool pressure can push the work away more the further you get from the headstock. If that is what is happening, you are seeing workpiece deflection, not a lathe error. Adding a tailstock center can help, or not, the tailstock has to be set up to be in line with the spindle axis of the lathe or it will cause its own errors. What kind of stock (size, material), and what kind of tooling setup do you have when making the cuts?
 
Using hand ground hss small nose radius. Cutting anything from 1/2" 1018 cold rolled bar to 1 1/2" 6061. Have even done some brass bar stock. Still seem to be getting this .001"_.002" taper. Always bigger on the tailstock side.
 
The .002" taper is over roughly 3". After work tonight I ran an indicator over the face of my 3 jaw chuck. I'm getting a .0045" error from operator side to the rear of the lathe (motor side).

I removed the chuck and indicated the face of the spindle. From front to back was less than .0005". TIR is basically 0.000. I moved to the farthest point of the spindle where the step is and had the same results. ? I wonder if it is the worn bed or the even more worn second hand chuck.
 
The headstock on my 12" Atlas/Craftsman was on crooked from the factory. I made a test bar on another lathe and use that with a dial indicator on the carriage to measure it. I had to do some filing on the indexing ledge that mates with the lathe bed. This involved a lot of removing the headtstock, filing a bit, reinstalling it and checking the test bar until it was right. It was a bit of a pain, but it can be done.
 
Or maybe I'm looking at the results wrong. The spindle seems to be dead on but the measurement with the chuck on puts it roughly .004" out on the motor side of the lathe. This would have me cutting a taper that is larger on the chuck side of the work being held?
 
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