flippin h***

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keithkarl2007

keithkarl2007

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Joined
Apr 22, 2008
Messages
1,727
Location
Ireland
I think my mandrel may be bent. Is it beyond repair? Will i have to get a new one? Could i keep it and shorten the bar for one blank pens like the sierra? Won't be able to get one for a while as beer vouchers are tight and the one available here in Ireland comes with 5 slimline kits which i just don't want as i already have quite a few. huff huff. That was a mouthful. Do mandrels vary in quality or will anyone do? How did i manage to bend it?:(:(
 
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when i sand the blanks they are flush on one side and on the other side of the bushing. I,ve just rolled it on the table and it seems fine. What else could it be?
 
Keith, if you tighten the nut on the mandrel too tight (or tighten your tailstock to tight), it will put a slight bow in the mandrel, which will cause you to turn/sand slightly out of round. Also, if you are sanding over your bushings you may have altered one of your bushings so that it is slightly flattened or out of round. If it is your bushing, then your blanks won't line up with your pen kit parts, and you will see or feel the difference when the pen is assembled. Like Roy said, slowly roll your mandrel on a piece of glass (this is better than a tabletop as it is almost totally flat). If it is not your mandrel, check your bushings, then check how you are tightening the nuts/tailstock. You just want them tight enough to keep the blank from spinning, no more (or not spinning when the lathe is on). Hope this helps.
 
thanks for that. i put the mandrel in on its own without the tailstock and spun it by hand it seems to be bent as it moves out of round. would the whole mandrel need replacing or can a separate bar be got for the centre
 
You've got nothing to lose by trying to straighten it yourself. I put mine between the headstock and tailstock line center and look for the high side. Then I use my thumbs to tweak it back to straight.
 
If your mandrel is like mine the bar just screws into the morse taper part of it. I have replaced mine once after the tail end of it where the tails stock rides in it became hollowed out enough that it concerned me. They have them at Wood Craft. I think I paid under $10.00 for it. Don't hold me to the price, but I am pretty sure I am right.
 
It is a long shot, but you could also try tapping out the entire mandrel (morse taper and all), then wiping the inside and outside of the taper clean before re-inserting. I once thought I had a bent mandrel but the replacement was not much better. It turned out to be a bit of crude in the morse taper "connection" that was throwing it out of whack. I cleaned it off and both old and new madrel shafts spun true again.
 
Tighten the brass nut too tight and the blank will bow. Tighten the tail stock will bow the mandrel. Doing both will compound the problem.

Reading Russ Fairfield's instructions about straightening a mandrel is excellent advice.

When you need a new mandrel make your own. Buy letter D (.246) size drill rod, cut to length and thread one end for the brass nut. Then you can cut mandrels to the length you need for the different kits.

Do a good turn daily!
Don
 
It could be that it is not the mandrel at all but your bushings, unfortunately they are not always true, i had the same problem once and bought a new mandrel and i still had the issue so i bought new bushings and the problem went away. of course now i turn between centers and no more problem:D
 
Can this be done for any pen, i'm still getting to grips with slimlines
Click to expand...

You'll need specially made bushings to turn 7mm between centers. You can make your own out of Corian, or purchase them from a couple of turners right here on this board.
 
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