Possible 7mm mandrel fix

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Forum topic by D_Allen posted 12-04-2011 06:03 AM 1038 views 0 times favorited 1 reply Add to Favorites Watch
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495 posts in 2746 days

12-04-2011 06:03 AM

I’ve got another idea…yea I know, that’s dangerous.
While making my second pen today I had problems with the blank getting out-of-round.
I use the mandrel saver but still you have to put pressure on the blank/bushing stack. There was noticeable slack where the brass tube rides the mandrel. Not much, so I measured it. There is a .002” difference between the inside of the brass and the mandrel size. However, if it gets loose and starts the assembly wobbling, it exaggerates the condition. So, what could I wrap around the mandrel to take up .002”? Even the thinnest sales receipt is too thick. However, tin foil is .001” thick. It is a bit tricky getting it into the tub and then onto the mandrel, but I tried one and it seems to work well.
Tomorrow I will try it on another pen and report back. It should also work on a sloppy bushing fit as well.

BTW, for those who may want to know. The drill bit letter ‘D’ is .246” and that seems to be exactly what the inside of the slimline brass tubes measure. The larger tube I have for the Artisan clicker pen measures .342”. An 11/32” is .3438”. I suppose I could take off that much by spinning it against some emery paper.
I may get a D bit for cleaning the glue out of the brass tubes. I’d be interested to know what the drill size is for the barrel trimmers.

-- Website is finally up and

1 reply so far

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495 posts in 2746 days

#1 posted 12-07-2011 05:09 AM

OK, here’s the deal.
The foil is a major PITA to use as setting it up is hit-or-miss.
The mandrel has a .004” run-out at the MT and the drive head has a .002” run-out in the point where the rod is pressed in. So I found the ‘sweet spot’ where there is about a .001” run-out at the mandrel.
However, there is play at the end of the mandrel too where it goes into the mandrel saver.
All this adds up to turning out of round blanks.
I am going with the center-to-center turning with special bushings. I can still use the mandrel for applying the finishes.

I’m gone!

-- Website is finally up and

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