[R-390] Bristol Clamp Screws

[jkharvie]

This is the screw, lock washer and square nutThe distance from the end of the screw to the socket head shoulder measures 0.508 inches Let me know if this works as a replacement.


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  On Mon, Jul 15, 2024 at 11:38, Barry Scott<72volkswagon at gmail.com> wrote:   ... and it just occurred to me that the smaller clamps may have shorter screws.  The screws for the large knob clamps are 9/16" long.  Is yours that long?
Thanks,Barry

On Mon, Jul 15, 2024 at 10:30 AM jkharvie <jkharvie at verizon.net> wrote:

Interesting!  I wonder if we have a collection of observed defected and other manufacturing irregularities.Yes, one screw surplus to my needs is yours, it is from a broken clamp that replaced with a split clamp configuration. Should be the size you need.John (N3JKE)




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  On Mon, Jul 15, 2024 at 10:41, Barry Scott<72volkswagon at gmail.com> wrote:   Looks like the front panel is about finished and turning my attention to
the knobs, escutcheon, and meter covers.

When I first removed the two large knobs a couple of years ago, I could
tell one of the clamp screws did not have the same spline-drive as the
other one as the socket was slightly larger than the other one.  I thought
someone had replaced the spline-drive with a hex-drive but yesterday, I
discovered that it is a larger spline socket.  Both are six-spline versions
but one is a 0.096" (Xcelite 99-66) and the other is a 0.111" (Xcelite
0.111").

>From what I can tell, they're both #4-40 screws but one is just a few
thousandths larger in diameter (not large enough to be a #5 and possibly
just manufacturing tolerance differences).

Also, one knob has the two ribs in it and the other doesn't.  I didn't
track which one had which screw in it and I don't think that really
matters.  Most likely, somewhere in a repair depot, a knob was installed
from a radio from a different manufacturer.

I'd like for these both to have the same Bristol drive (the 99-66 0.096"
version) so as to match the screws from all the other knobs.  Anyone know
where I could get a proper socket-head screw for this?  I know these are
pretty rare and likely the only place I'd find that is from another
clamp/knob/radio but thought I'd ask.

Thanks,
Barry - N4BUQ
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