Fat Boy Advice Needed

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lawry76

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May 5, 2005
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Peoria, Illinois, USA.
I just turned a fat boy pen, made my own CB, but when I put it together it was out of balance, lopsided. So when you turn it to release the pen tip, it no longer mates at the center band. The variation is slight, but I sure notice it. I suspect it is a mandrel problem, although I checked it at the beginning. Or I checked it rather casually. It was a bit of a disappoinment to me because the pen turned out great. Thanks
 
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If you are very picky, even the smallest amount of runout is a pain to deal with. With our mandrels being what they are, they flex, bend, and need frequent tuning. For reducing eccentric outcomes on custom CB pens, when you have it down to final size and shape, loosen the nut on the mandrel, and rotate the barrels by hand to a different position. Then re-tighten the nut and work on them again. If you do this several times, you should end up close to perfect.

Edit: also read the thread Jim just gave you. [:)]
 
Tim gave you great advice. Another way to skirt the issue is to have a CB that has a bead or a cove (see Yo-Yo Spin album) which has a larger diameter than the mating ends and even if it is off a bit it will not be noticeable.
 
There seem to be two problems that always follow us.

1st is that the mandrels are not straight. Look at this page for some help here.
http://www.woodturnerruss.com/Pen12b.html

2nd is blanks whose ends are not square with the brass tube. A bent pilot on a pen mill will cause this problem. Always check that the pilot doesn't wobble.

Sanding the ends of the blanks requires that the brass tube is square to the sanding disc.

You are on your own if you are sawing the ends. Square with the outside of the wood doesn't mean square with the brass tube.

You can get around slight problems by releasing the pressure on the mandrel nut before making the final cuts and sanding. You will be surprized how little pressure is required to hold the blanks after they are round.

There is a 3rd thing that can happen, and that is bushings whose ends are not square. This one is fairly obvious if we are looking for it.
 
I'm with Russ's second suggestion. It is likely that your blank was not faced to the tube properly. When this happens, probably more times than you realize, it is much more evident on larger size kits.

Fangar
 
I have begun using the blank trimmer after taking the finished pen off the lathe. This in addition to pre-turning squaring with disk sander and/or barrel trimmer. There is so little wood left after turning that any irregularity comes off quickly. I find this helps.
 
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