Trouble with Mandrel?

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willardz

willardz

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Jul 1, 2007
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Location
Smyrna, GA, USA.
The last couple of pens that I have made have one end that is not fitting properly.One side is thicker than the other.Would this be the Pen Mandrel slightly being bent? I am hoping there is nothing wrong with the Lathe. I have a Jet Mini Lathe and I bought about 4 months ago. Also would this be because of Vibration from not being Mounted, I have it on a work table. What do You think.
Thanks,
Zeke
Atlanta
 
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Bent mandrel. Not as likely, but could be bad bushings. Most likely bent mandrel.
Look here, tutorial for straightening a bent mandrel.
http://www.woodturner-russ.com/Pen12b.html
 
Go get another mandrel. Remount the blank and re-turn it just a bit and see if you can get the thick, wobbled part to turn round. Besides, it never hurts to have several mandrels on hand just in case you ever do bend one which always happens after the stores have closed for a long holiday during which you thought you were going to be turning ... Murphy's Law, dude. [:)]
 
Pull the tailstock away from the mandrel with the taper well seated in the headstock and turn on the lathe at a very slow speed. See if the mandrel whips like it's bent. If it does, loosen the nut or remove it and the blanks. If it still whips, it's the mandrel, if not, the blanks were not square. When you tighten the mandrel nut, it will force the mandrel to bend a little to conform to the blanks and cause it to turn out of round. Good luck.
 
The Pen Kit I am using is for the Navigator. Also I did not purchase an aftermarket 60 degree live center. I am using a mandrel from Rockler which I have had since I bought the lathe. I started with Slimlines on it. I believe the Mandrel is bent after doing the tests which were suggested.Thanks. I am going to buy a new mandrel.

Thanks,
Zeke
Atlanta, GA
 
Unscrew the mandrel from the arbor and then roll it on a flat surface like a pane of glass. If it is bent, it will be very obvious.

It would be a good idea for you to invest in a 60° live center. A lot of people like the #1189 from The Little Machine Shop that runs about $13, IIRC.
 
In the interim, if you are ordering new parts, once your piece is turned close to the bushing, unscrew the nut and rotate your work piece 90 degrees(not whole assembly)and turn some more. This should even it out.

I have used this method a couple times and worked. I had Bent my mandrel buy overtightening it.
 
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