[R-390] R390 knob set screw

[John KA1XC]

Dan,
my notes say it's 8-36 UNF thread, yet another oddity of the 39x's. If you
had the tap you could epoxy the hole and drill and retap it but a
replacement knob can be gotten cheaper.

Sometimes you can smear some JB Weld across just the damaged area, let it
firm up a bit, and then use the setscrew itself as a tap, then remove it and
let the JB cure. If your lucky it can give the setscrew the little extra
bite it needs to do the job.

That phenolic insulating shaft on the 390 is pretty tough, I wouldn't worry
too much about hurting it.

John


----- Original Message ----- 
From: "Dan Merz" <djmerz at 3-cities.com>
To: <r-390 at mailman.qth.net>
Sent: Thursday, April 14, 2005 12:22 AM
Subject: [R-390] R390 knob set screw


> Hi,  I ran into a minor problem.  The set screw in one of the larger knobs
> (on the ant trim on R390) doesn't want to tighten against the shaft and I
> see that the threads in the knob are damaged in the area near the shaft
and
> the screw likes to just ratchet back at the critical point of tightening.
> It's the knob not the set screw that's the problem.  I think a longer set
> screw of 3/8 length would solve the problem.  What is the thread
size/pitch
> on these set screws? I make it to be 8-36, an unusual size these days.
Are
> there some screws longer than the standard 1/4 inch length in somebody's
> pile?  The other alternative is to drill and tap it for the next larger
size
> set screw but who wants one knob to have a different size wrench, hi?  I
> guess I could shove a piece of solder or piece of plastic in front of the
> short one and hope for the best.  The trimmer shaft looks like phenolic so
> I'd like to treat it nicely.  Any advice on fix appreciated,  more later,
> Dan.
>
>
> _____________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:R-390 at mailman.qth.net
> Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>