On Wednesday, July 21, 2010 12:06:38 pm Andy Pugh did opine:
> Given a 12mm / 1/2" thick aluminium / aluminum disc / disk of 80mm /
> pi" diameter with a thread on the entire cylindrical circumference,
> how best to lock the thread in place in a way that can be easily
> reversed and which will not damage the threads in such as way as to
> inhibit dismantlement?
>
> Ideas I have include a sort-of tangential saw cut through a
> part-threaded (with a taper / first tap) hole with a grub screw /
> setscrew in it (winding the screw into the unthreaded part pushes the
> slit open, locking the thread), A saw-cut in the plane of the disc /
> disk with a screw to locally squeeze or stretch the thread pitch to
> lock it, and a variant of the first idea where a wedge of the disc is
> cut out after the hole is part-threaded (possibly located with
> half-and-half roll pins).
>
> Any other ideas, or approaches that anyone has seen?
My first idea would be to saw a slit in the part with the internal threads,
and drill/tap for a small cap screw to squeeze the outer part down to the
alu plug.
But I also would have to assume some means of sealing the slit against
leakage would be required, so perhaps its not a good idea at second
thought.
One could also fit it in two pieces perhaps by rigging a ledge on the outer
edge, with spanner slots cut in the full thickness central portion, and cap
it with another thin ring, also with spanner slots, such as can be seen in
the exposed ends of a riflescope or binocular objective. But with two
working diameters of the spanner slots, two wrenches could then adjust the
plugs depth and lock it at that depth with the 2nd ring. That would be a
bear to fabricate though, best done as one piece, then the lock ring parted
off with a very thin cutoff tool meeting a thin groove cut in the top face,
and an o-ring fitted between them for locking pressure. With the right
choice of o-ring sizes, it should be able to hold a considerable pressure
if the o-ring expands both to block the visible groove in the face, and the
threads are also sealed by its expansion the other way. If there is no
leakage control needed, to heck with the o-ring. Re-reading your
description tends to say it doesn't have to be leak-proof
I don't like the roll pins as they would prevent truly fine adjustments.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
May's Law:
The quality of correlation is inversly proportional to the density
of control. (The fewer the data points, the smoother the curves.)
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