mandrel problem

curiousgeorge · Post by **curiousgeorge** » Sun Dec 14, 2008 2:14 am

rdewinter wrote:I must not have clearly stated the problem. The pen blanks don't spin on the tube but on the mandrel. I rough up the tube, use CA glue and square the ends with a pen mill. I tighten the curled nut by hand. I get slippage on a square blank with too heavy chisel pressure. Once the blank is rounded I have no problem. Maybe the solution is to take lighter cuts. I might be a little too aggressive when first starting to turn.

Bob
San Diego

PS: I ordered the DVD from Penn State but I never got it. Bummer!

Refer to post #6 step #5....

nuhobby · Post by **nuhobby** » Sun Dec 14, 2008 7:39 am

Yes, all the above is good advice. Also, in the context of safety, some drive slippage threshold is good on the lathe. Infinite torque could be pretty dangerous. (This reminds me of Bill Mayo's posts on the slip clutch inside the old Gilmer drive sleeves.)

flyslinger · Post by **flyslinger** » Sun Dec 14, 2008 11:07 am

Rdewinter

I talked to a guy at Rockler and he told me that a little turning of the rough blank is okay, just hand tighten a little more and lite pressure until the blank is round . On a side note I also raised my SS 8" off the floor for my turning and that took the stress off my lower back......they say that the center of the spindle should be equal to the center of your elbow. good idea if you are going to be turning several pens in a row....

fjimp · Post by **fjimp** » Sun Dec 14, 2008 1:38 pm

Bob,

What you are experiencing is normal enought. I could suggest two options. First would be to set your bandsaw at a 45 degree angle and cut off the corners of your blanks.

The other is to set the lathe speed as slow as possible and use a feather touch in approaching the blank. Grabbing or spinning simply indicates you are a bit too agressive in approaching the hard corners of a blank.

I guess a third options might be to use your belt sander or a sanding disk to take a corner off. If doing this I would want thave some sort of jig to hold the stock so I don't get hit by it when it takes off. The bandsaw is still the best option. I have designed a jig to hold pen blanks at a 45 degree and for use on the band saw but never taken time to build it. fjimp