If the standard sized bore is 5/16" why not make a mandral from a
heavier piece of round stock, say 3/4". Make a section that is turned
to just under 5/16" Make two larger flanges to support the wheel your
turning that will it on this section in addition to the thickness of
the disk itself, and then thread the remaining portion so a nut or
threaded flange or collar can be snugged up to the disk. Pl;ace the
reduced sectin of the round stock in a collet, and use a live center
to support the opposite end. Aftere completion of machining the disk
round, use a ream to enlarge the hole to 5/16". I would imagine you
could make the intitial hole 5/16" to start with as well.

Becarefull of that phenolic your using as its known to be a
carcinogenic material the dust / smell is highly irritable to nasal
cavities and lungs. It was so much of a hassle to just even drill the
stuff where I used to work with having to have special ventilaors etc
that we soon just stopped doing anything with it in house. I like
working with it myself.



On 5 Aug 2003 22:32:51 GMT, (Alden Hackmann)
wrote:

x-OK, so here's the situation: We make this weird instrument (see www.hurdygurdy.com). It has a rosined wheel, turned by hand
x-by the player. For about a year we've been making the wheel from a linen-filled phenolic, which is wonderful - no moisture
x-sensitivity, much less machining time. The only downside is how long it takes to scrape the wheel so it has no runout.
x-
x-So at breakfast my wife asks me why the wheel always needs to be scraped, i.e. why doesn't it come from the lathe with no
x-runout - and I have to say I don't really know. I then postulate that it's because the wheel and shaft inevitably exhibit
x-some chatter when turned on the lathe. and I wonder what I can do about it.
x-
x-The shaft is about 7" long, and the wheel is 7" diameter x 3/4" thick phenolic. The shaft diameter is 5/16", O-1 drill rod,
x-held between a 5/16" A3 collet and a live center. The wheel is about 5" from the wide end (in the collet) mounted on a
x-threaded region, supported by a collar. I'm using a South Bend 9".
x-
x-Any suggestions for how I might turn this material with less chatter? For example, what side rake and back rake angles are
x-best for phenolic resin? A slow speed seems to help, but doesn't eliminate the problem. The shaft would still be relatively
x-"floppy". I could turn the wheel on a thicker, heavier shaft, but then it wouldn't be being turned on the actual shaft that
x-will be used.
x-
x-
x-Your help appreciated, as always,
x-
x-Alden

--
Visit my website:
http://www.frugalmachinist.com
Contents: foundry and general metal working and lots of related projects.
Regards
Roy aka Chipmaker // Foxeye
Opinions are strictly those of my wife....I have had no input whatsoever.
Remove capital A from chipmAkr for correct email address