[ARC5] Receiver covers...

[Michael Hanz]

"Kenneth G. Gordon" wrote:
> 
> I have a number of really good ARC-5/SCR-274-N receivers here
> which have beat up covers.
> What do you all do to repair these? Some have the cover studs
> missing. Others are just bent up.

I use a variety of small ball peen hammers and body bumping tools along
with several sizes of soft pine blocks and a BIG vise to clamp them in -
you need quite a bit of overhang with some dent geometries.  Each dent
is a special case.  The cover is so thin that your fingers and a little
muscle is sometimes better than mechanical help - especially for longer
swales and curves.  Unless the paint it already in bad shape from
moisture, it won't come off with a little careful tapping and working.

> The bent ones I can fix pretty well, but what does one do about the
> studs?

Make them on the lathe...  :-)  For a couple of particularly nice covers
I've had come through here over the years, it was easier to make the
rivet posts out of stainless and rivet them in than to try to resurrect
a couple of posts from junk covers, though that procedure *is* possible
with some care.  For the courageous, I'll describe a fairly precise way
to do that - you can modify as you see fit and to be compatible with
whatever tools you have.  Getting them out of a junk cover is easy -
just use a hollow tube or small socket to back up the cover material and
tap them out using a pin punch of the inner diameter of the hollow ended
rivet.  The more difficult task is reversing the rolled-over end of the
hollow rivet.  I stick it in a collet in my lathe, along with a "live"
center in the tailstock that has an extension the same size as the pin
punch used to remove the rivet.  That gives you a stable shaft to roll
the flared head back on.  Then, using a low speed, you essentially do a
metal spinning operation to straighten out the flared end to a cylinder
once more.  I have a box full of old dental tools I use for this kind of
procedure, followed with a 1/2 x 1/2 square oak bar to finish off and
polish the tubular end you have just restored.  Sometimes the oak bar is
enough to do the entire operation.  Depends on how clean the end came
out.

Now, I have to admit that's a fair amount of work when you compare it to
just making a new one, so it has to be worth it to you to retain an
original part.  It is also not foolproof, and you may have to perform
the operation on more than one to get an acceptable post for
re-riveting.  The original nickel plated brass is fairly workable, but
the riveting operation is hard on it, and you shouldn't be surprised if
a few cracks are left in the tubular part after restoration -  a few
more may appear when you re-rivet it in the cover you are trying to
restore.  Shouldn't make any difference in your basement shack, though. 
You should also keep in mind the fact that the hole destined for the
post may be oversized, so it may not be necessary to flatten out the
original rolled over head completely.  Trial fitting as you work the
head back to original shape is highly recommended - the idea is to do
the minimum required to get it to clear the hole it's going through. 
Nothing wrong with using a tiny washer if the hole is too big, either. 
Luckily, if you're lazy like me and decide to just make a new one, 303
stainless is indistinguishable in appearance and it saves making up a
barrel plating solution.  Like all stainless it does work harden, so you
effectively only have one shot to set the rivet - it has to be a sharp
rap if you're using the center punch method.  Subsequent beating on it
will only split the hollow end, so follow on taps should be lighter and
just for the purpose of folding the top over slightly with a shallower
tip (larger) punch.

Enough metal pounding for a Saturday morning,
Mike