(DoN. Nichols) writes:


The nut doesn't have to *look* like a nut. It can be a cone,
with pin holes or grooves (which could be disguised as decoration)
allowing a special wrench to tighten it firmly.

Hmm - I'd need to think about that.

How thick is the wheel at the hub? What pitch are the threads?

3/4" thick wheel, 5/16-18 threads

I think that you are using a wheel of about 1/2" thickness, which is not
really enough if half of its length is taken up by threads. And the
rather coarse threads which would seem to make sense in phenolic would
result in not enough of them to really trust.

Then 3/4" should be fine.

Otherwise, this is similar to how a lathe's spindle centers its
chuck, with a register shoulder and threads for the force.

Cool - got it.

Do you ever encounter a player who likes to turn the wheel
backwards most of the time? Do you have problems with it coming off
under those circumstances?

It's quite an unnatural motion. A very few players use a quick
back-and-forth motion sometimes for a special effect. We have
occasionally had difficulties with the wheel coming undone when the crank
is removed, as players often do when storing the instrument. To this end,
we have been milling a small pair of flats on the exposed end of the shaft
for a 1/4" box wrench. (The old method was a pair of Vise-Grips(TM) -
yuck!)

I would think so. Would the half that's
bored straight be enough to stabilize it? That's the way we used to do
it, with a nylon insert in a wood wheel, until we had several incidents
of the nylon threads being stripped.

I think that this answers your question. :-) It just isn't long
enough to devote half of the thickness to threads and half to a reamed
hole for centering.

Does the shaft stick out much beyond the hole? If not, a
cone-shaped nut could look rather nice, and be a lot stronger than the
phenolic, let alone than the nylon.

The shaft extends about 1.4", into the head bearing.

BTW Have you looked into using Delrin (acetal) for your wheel? It
is available in both Balck and natural (a sort of light cream
colored white. and is a lot more durable than nylon.

We need the rosin to stick, and for the material to be completely stable
regardless of the humidity.

Good luck,
DoN.


P.S. Can you trim your line length a bit? Standard length should
be no longer than 72 characters, to allow some levels of quoting

Sorry - I'm using ASCII, but the screen was really big. Hopefully my
resizing to 80 columns has solved this.

Alden
--
Alden F.M. Hackmann
Web: http://www.hurdygurdy.com/hg/hghome.html
"Beati illi qui in circulum circumeunt, fient enim magnae rotae."