[R-390] R390 knob set screw - JB Weld

[Patrick]

Three years ago I epoxied the side cover of the electric starter for my 18HP 
lawn tractor that came apart in several pieces, so far working perfect. It 
is a great product.

Pat
----- Original Message ----- 
From: "John KA1XC" <tetrode at comcast.net>
To: "Barry Hauser" <barry at hausernet.com>; "R-390 reflector" 
<r-390 at mailman.qth.net>
Sent: Thursday, April 14, 2005 1:48 PM
Subject: Re: [R-390] R390 knob set screw - JB Weld


> Barry,
> I didn't know there was a quick set version, all I've used so far is the
> regular stuff  which is dark grey after mixing. The next time I'm out
> shopping I'll look for the quickie stuff out of curiosity.
>
> Check out  http://jbweld.net/index.php especially the FAQ and technical
> section, it has some of the info you seek.
>
> Yes, I've also noticed that it is a pretty good match for the front panel
> and its shade can also be altered depending on the resin/hardener mix 
> ratio.
> It also can be thinned with the usual paint solvents.
>
> They call it a "steel" epoxy. The MSDS info didn't say anything about 
> steel
> but the two components do contain calcium carbonate, iron powder, and 
> barium
> sulfate in large parts which probably account for it's hardness and
> machinability.
>
> They also said in the FAQ section that the quick set version is only half
> the strength of the original JB, which agrees with my thinking that the
> longer set time epoxies are inherently stronger. I'll use quick set epoxy 
> on
> tiny parts and things that don't require a lot of strength  but use the
> longer cure time stuff  elsewhere.
>
> I just epoxied part of  a hair dryer power switch back together where the
> switch contactor broke away from the finger slide part of the switch. It 
> was
> an easy fix but I couldn't believe how freakin' weakly they designed the
> broken joint; for lack of a bean sized amount of additional plastic they
> created a very weak link. So besides gluing the original break I also 
> filled
> in the entire hollow end of the joint and now it's strong as a rock.
>
> 73,
> John
>
>
>> Hi John
>>
>> Coincidentally, I have a question about JB Weld.  I just used it to 
>> repair
> a
>> small folding table which was inadequately glued to start with.
>>
>> I'm more accustomed to regular and quick-cure epoxy which is clear.
>>
>> Had some small tube sets of JB weld somewhere, but lost track of it.  I
>> picked up some at Pep
>> Boys -- big box "J-B Industro Weld, Cold Weld Shop Size"
>>
>> This stuff when mixed is medium to light gray.  Are all of the J-B Welds
>> that color?  I also picked up the small tubes of the quick set version.
>>
>> That grey looks very similar in shade to the "right" shade for R-390 
>> front
>> panels.  Anyone try it to detail out a chip?  Might not even need
> touch-up.
>>
>> I used to assume J-B was the same basically as regular epoxy glue, but
>> possibly better quality.  Must be something very different as it doesn't
>> have that characteristic annoying aroma.  It also cleans up a heck of a
> lot
>> easier.
>>
>> Barry
>>
>> ----- Original Message ----- 
>> From: "John KA1XC" <tetrode at comcast.net>
>> To: "R-390 reflector" <r-390 at mailman.qth.net>
>> Sent: Thursday, April 14, 2005 12:21 PM
>> Subject: Re: [R-390] R390 knob set screw
>>
>>
>> > 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.
>> >>
>>
>
>
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