Vibration Image on the pen

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bekeeper

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Jan 17, 2014
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I have an old Delta D40 lathe. I have been seeing and hearing vibration marks on the side away from the headstock. I have changed a pulley that had a chip, changed bearings on the top shaft, realigned the pulleys to make sure the is not rubbing. I bought one of the new mandrel holders where the out board side slides into the revolving tail stock bearing. Still I get this slight pattern in the blank that is easily sanded but still it should not be there. I have been up and down on the tightness or pressure on the blanks pushing toward the head.

Does anyone have any ideas on how to stop this or where it is coming from.

:mad::mad::mad::mad:​
 
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Bent mandrel? Take the tailstock away and see how much "whip" there is in the end as you turn by hand (you can use the toolrest as a reference point)
 
I have seen what you are describing on my lathe at times. When I see it is when I am turning with a mandrel and turning a two piece blanks and usually see it on the blank closest to the tail stock. I think mine is from the mandrel deflecting as I turn, and it seems to be worse when my tool is dull. I never see it when turning between centers and very seldom with an Aero or Sierra blank.

I would check the mandrel and make sure it is not bent, also make sure your tools are sharp.

Mike
 
I second their advice. First check that your mandrel isn't bent and the alignment between head and tail are right. Then, make sure your tools are sharp. A properly sharp tool should require very little effort to use.
 
Make sure you are not overtightening the nut on your mandrel.

Try putting a center in your head and tail stock and push them close together, you may be a little off center on one end.
 
The marks are from turning off center, then having the blank rotate slightly vs. the mandrel, and making more cuts. (Or it could be chatter from a dull tool or pressing too hard against the blank, causing the mandrel to flex).

As others have mentioned, check your mandrel to make sure it is perfectly straight. I use a cheap dial indicator from HF, along with the magnetic base. I remove the ball from the bottom of the indicator and it works much better against a mandrel. Total cost was less than $20, and I use it on a lot of things, so well worth it.

I have also had that problem when I used bushings that were not made correctly. The hole in the center was not quite centered.

My solution for a lot of pens now is to just turn between centers, but that's a whole 'nother ball of wax.
 
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