[R-390] Bristol Clamp Screws

[Barry]

Hello Jacques,

You're measuring overall length.  The length of a cap screw is typically from the shoulder to the end of the threads.  I think the screw you're showing is the same length as John's.

Thanks,
Barry - N4BUQ

----- Original Message -----
> From: "Jacques Fortin" <jacques.f at videotron.ca>
> To: "jkharvie" <jkharvie at verizon.net>, "Barry Scott" <72volkswagon at gmail.com>
> Cc: "R-390 Mailing List" <r-390 at mailman.qth.net>
> Sent: Monday, July 15, 2024 12:31:00 PM
> Subject: Re: [R-390] Bristol Clamp Screws

> Barry and JK, the original screws for the "big knobs" clamps are 0.692 inches
> long.
> See attached picture.
> But the ones I still have are "eaten" in their internal splines.
> The other that are assembled in the clamps in my picture are (more available)
> stainless hex ones.
> Do not forget to have the small washer fitted in the clamp to prevent it to turn
> around when you try to tighten the screw(s).
> 
> 73, Jacques, VE2JFE in Montreal
> 
> -----Message d'origine-----
> De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De la part de
> jkharvie via R-390
> Envoyé : 15 juillet 2024 12:03
> À : 72volkswagon at gmail.com
> Cc : r-390 at mailman.qth.net
> Objet : Re: [R-390] Bristol Clamp Screws
> 
> 
> 
> 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.
> 
> 
> Sent from AOL on Android
> 
>  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)
> 
> 
> 
> 
> Sent from AOL on Android
> 
>  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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