Turning eccentric

I have asked about adjusting the rear bearing but have never been told that it needs to be adjusted. The owners manual only shows adjusting the middle bearing inside the headstock. The rear bearing is a double roller ball bearing and has the same type of adjustment collar on it.
 
I have .0003” of run out on the spindle. I checked it inside and on top of the taper. This was with the lathe cold. I’m going to check again after running it a while and see if there’s a change.
 
BWS Arms said:
I adjusted my headstock bearings because I figured they needed it based on how freely the chuck rotated. They are running nowhere near hot but now my lathe is turning eccentric. I aligned the headstock and have it perfect. I have less than .0001 over 10”. I purchased the lathe knowing that it had a noisy headstock but hoped it was just needing an adjustment.
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I'm at the WTF moment.
Sorry.
You adjusted your headstock.. not because you had a problem, but because you felt the chuck should rotate more freely.
You didn't explain any problem.

You have gone the opposite way of what I would have done.
You loosened it, and made it ???? better or worse... worse
But now you think you have a bent spindle??? HOW
It's not easy, no it's NEARLY impossible to bend your spindle..
I would tighten your spindle back up, generally they loosen over time, not get tighter.
I have not read ALL the post, because I was so amazed how without describing a real problem you made an adjustment and things went bad, and now you are possibly blaming everything under the sun.

Excuse me if I am offbase.. My feeling is your first move was the wrong move.
 
I had a suspected bearing knock and finish issues. I tightened the headstock bearing. I did not loosing it.
 
What lathe is it ? On my lathe you can only adjust the preload not individual bearings.

Mostly you set it so the spindle isn't free spinning without a chuck but isn't stiff either (if that makes sense).

Running it at top speed for a bit and measuring the bearing temps as you have been doing is a good idea.

Stu
 
BWS Arms said:
It’s a supermax 1660. Same as Victor 1660s.
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If you feel it's not cutting round then you should be able to measure a difference in size at 90 degrees apart on the test cuts your making.

Have you got anything round and accurately sized ? examples would be a test bar , some ground shafting maybe a chromed stanchion from a suspension strut.

In combination with a dial indicator you may be able to hunt down what is happening. Also you can give the bar a push in different directions to see if the bearings are tight enough. (lathe not turning just pushing the bar in the chuck, probably need to be a couple of feet in length for this)

edit , ... Push it about with a basic bit of bar stock not your know good one ! :)

Stu
 
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BWS Arms said:
Its more obvious in this clip. Its cutting heavier on one side. I had already made multiple passes and even blued it to be sure it was making a full cut.
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If the problem was turning eccentric you'd expect it to change once a spindle revolution. The sound is changing once a second but you are turning way faster than 60rpm, so it's gotta be something else.

Maybe a bent lead screw causing the feed rate to vary? Change your feed rate or try feeding manually and see what happens...
 
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