Turning eccentric

[BWS Arms]

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.

 

[matthewsx]

Can't open your video on work computer. Is this after you take a cut on that material? Should be concentric to the spindle regardless I think.

John

 

[sdelivery]

Are you saying your part is egg shaped? Yet you have no taper?

 

[BWS Arms]

Watch the video and you will see that it cuts heavier on one side than the other. I only measured the diameter at one place while doing the two collar test but the part can’t be round based on the way it’s cutting.

 

[BWS Arms]

I think it’s going to need a set of bearings. I sure hope the spindle isn’t bent.

 

[BWS Arms]

Are you saying your part is egg shaped? Yet you have no taper?

I have no taper over 10”.

 

[matthewsx]

Measure the spindle.

 

[BWS Arms]

I’m going to pull the chuck and set up a tenths indicator on the inside of the spindle tonight.

 

[RJSakowski]

Unless you have excessive play in the spindle, it would be nearly impossible to turn an eccentric. Even then, the symptom would be rough finish and chatter.

Play can easily be checked bu mounting a rigid shaft in the chuck and bringing a dial indicator into contact. If there is play, you will see the reading change as you push or pull on the chuck.

Three jaw chucks usually don't locate work concentric with the spindle axis, That is why we use four jaw chucks and dial in the work. Depending on the chuck and how much wear it has, you can see eccentricity of .010" or more. The lathe bearings should be preloaded so they will be slightly warm after use and there should be no axial play.

 

[BWS Arms]

I only have the 10” Bison 3 jaw for this lathe.