Repairing Plastic

The faceplate on my Narco CP-136 Audio Panel was broken off (and glued back
together) before I bought the plane. The left side of the faceplate, where 2
retaining screws attach it to the metal chassis, had been glued at least
once before I bought it, and my avionics shop had glued it back together for
me twice.

All to no avail. In extreme cold, the glue would simply let go. There
simply wasn't enough original plastic left for the epoxy glue to grip.

So, when I picked up my plane from its recent transponder installation, I
was not surprised when the faceplate suddenly popped out on the left side
during the climb-out. (Hey -- everything in the panel had actually WORKED as
advertised for a good 2 minutes! :-) Vowing to somehow permanently fix the
damned thing, I jumped on line when I got home...

Suffice it to say that the alternatives I found were not good. The cheapest
solution I found was a used unit for $175 on Ebay. Narco wanted $200 (!)
for just the faceplate. At that point, I knew it was worth taking some time
and thinking this thing through -- so I pulled the audio panel out of my
minus 10 degree hangar and took it home to warm up in my workshop.

After raising it almost 80 degrees to room temperature, I carefully removed
the screws from the remnants of the original plastic. It was obvious that
some meathead had yanked it out -- hard -- by the faceplate, in an attempt
to remove it from the panel. They probably didn't realize that the
installation allen screw on this unit was the kind that you could turn
forever, until it literally backed the unit right out of the panel. (Some
radios just have allen screws that lock or release the unit from the panel,
which results in you having to then slide them out "manually" with a yank or
two.)

After too many gluings, the plastic around the screws was just a mess. When
I backed the screws out, the piece literally crumbled, leaving nothing left
to glue. I now had a rectangular faceplate with NOTHING at one end to screw
through. (For a visual image of this, imagine a shoe-box lid with one end
cut off...)

Now what?

With nothing to lose, I wrapped the end of the faceplate with a piece of
strapping tape -- the only thing I could think of that would be strong
enough, yet removable. I then C-clamped the faceplate on end, so that the
missing end was flat on my work-bench. I then started mixing up a batch of
J-B Weld...

J-B Weld is a 2-part mixture, rather like a thick epoxy except that it
applies like a "flowing" putty. It fills large voids, dries without
expanding (or contracting) into a rock-hard texture, and can be drilled, cut
and sanded. I carefully spooned my first batch into the void framed by the
strapping tape and the sides of the faceplate, making sure it was in contact
with the sides and back without over-flowing anywhere, and let it dry over
night.

The next day the new part looked good (better than expected, as it had
"gravity-smoothed" perfectly) and was well adhered to the sides -- my
faceplate had an "end" again! Still, it was a bit thin, and I didn't want
to take the chance of it breaking when I tried drilling it. So, another
batch of goop was mixed up, and I carefully built up another layer, packing
it in but again making sure not to over flow the edge of the tape...

Next morning it looked much more stout, but -- since the weather was
absolute crap anyway -- I mixed up another batch and used it to reinforce
the OTHER end, so it wouldn't break off someday, too. I also packed some
into the corners of the piece (using a toothpick) to reinforce some stress
points, and filled in a couple of cracked areas from behind while I was at
it. This was tedious, as the pieces are small, and you have to be careful
not to add material to spots that need to clear certain parts. (Like the
light bulbs for the marker beacon lights...)

The following afternoon it was time for the big test -- could I actually
drill this stuff without breaking the new "end" out completely? I first
carefully removed the strapping tape, and was surprised when it came off of
the new material rather easily. I then marked where the holes needed to go,
chucked the piece on end into my drill press, and EVER so carefully lowered
the spinning bit into the new plastic.

You can imagine how relieved I was to find that it cut through just fine.
The new J-B Weld plastic was just as strong (maybe stronger?) than the
original part, and I quickly finished drilling both holes.

It was a little spooky counter-sinking the holes for the screw heads, since
it meant hitting the piece with a fairly large drill bit. Again, however,
it held up to the drilling force just fine.

Upon reassembly, however, I discovered that my new end was JUST a tad
thicker than the original -- I had reinforced it a bit much. This didn't
allow the faceplate to mount on the audio panel chassis properly, so, using
the spinning bit in my drill press like a router, I carefully hogged out
tiny bits of the new material at a time, until it fit perfectly.

All that was left was the cosmetic touches. Using some flat black model
paint (J-B weld dries to a light gray color), I painted the new material to
match the original plastic. Since the repair is almost entirely on the side
of the faceplate, it's nearly impossible to see the new piece, and -- after
painting to match -- you can't see it at all.

I reinstalled the unit today, and it fits, looks, and works as good as new.
J-B weld is amazing stuff, and I'm $200 ahead because of it.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Sun, 01 Feb 2004 21:57:29 GMT, "Jay Honeck"
wrote:

snip

I reinstalled the unit today, and it fits, looks, and works as good as new.
J-B weld is amazing stuff, and I'm $200 ahead because of it.

Now invest some of that money in a Dremel tool and I'd bet you'll be
able to literally sculpt your next J-B Weld project.

Don

"Sharpie" brand permanent markers make excellent "touch-up" tools for
most black instrument surfaces. Much easier than painting.

Rip

Jay Honeck wrote:
The faceplate on my Narco CP-136 Audio Panel was broken off (and glued back
together) before I bought the plane. The left side of the faceplate, where 2
retaining screws attach it to the metal chassis, had been glued at least
once before I bought it, and my avionics shop had glued it back together for
me twice.

All to no avail. In extreme cold, the glue would simply let go. There
simply wasn't enough original plastic left for the epoxy glue to grip.

So, when I picked up my plane from its recent transponder installation, I
was not surprised when the faceplate suddenly popped out on the left side
during the climb-out. (Hey -- everything in the panel had actually WORKED as
advertised for a good 2 minutes! :-) Vowing to somehow permanently fix the
damned thing, I jumped on line when I got home...

Suffice it to say that the alternatives I found were not good. The cheapest
solution I found was a used unit for $175 on Ebay. Narco wanted $200 (!)
for just the faceplate. At that point, I knew it was worth taking some time
and thinking this thing through -- so I pulled the audio panel out of my
minus 10 degree hangar and took it home to warm up in my workshop.

After raising it almost 80 degrees to room temperature, I carefully removed
the screws from the remnants of the original plastic. It was obvious that
some meathead had yanked it out -- hard -- by the faceplate, in an attempt
to remove it from the panel. They probably didn't realize that the
installation allen screw on this unit was the kind that you could turn
forever, until it literally backed the unit right out of the panel. (Some
radios just have allen screws that lock or release the unit from the panel,
which results in you having to then slide them out "manually" with a yank or
two.)

After too many gluings, the plastic around the screws was just a mess. When
I backed the screws out, the piece literally crumbled, leaving nothing left
to glue. I now had a rectangular faceplate with NOTHING at one end to screw
through. (For a visual image of this, imagine a shoe-box lid with one end
cut off...)

Now what?

With nothing to lose, I wrapped the end of the faceplate with a piece of
strapping tape -- the only thing I could think of that would be strong
enough, yet removable. I then C-clamped the faceplate on end, so that the
missing end was flat on my work-bench. I then started mixing up a batch of
J-B Weld...

J-B Weld is a 2-part mixture, rather like a thick epoxy except that it
applies like a "flowing" putty. It fills large voids, dries without
expanding (or contracting) into a rock-hard texture, and can be drilled, cut
and sanded. I carefully spooned my first batch into the void framed by the
strapping tape and the sides of the faceplate, making sure it was in contact
with the sides and back without over-flowing anywhere, and let it dry over
night.

The next day the new part looked good (better than expected, as it had
"gravity-smoothed" perfectly) and was well adhered to the sides -- my
faceplate had an "end" again! Still, it was a bit thin, and I didn't want
to take the chance of it breaking when I tried drilling it. So, another
batch of goop was mixed up, and I carefully built up another layer, packing
it in but again making sure not to over flow the edge of the tape...

Next morning it looked much more stout, but -- since the weather was
absolute crap anyway -- I mixed up another batch and used it to reinforce
the OTHER end, so it wouldn't break off someday, too. I also packed some
into the corners of the piece (using a toothpick) to reinforce some stress
points, and filled in a couple of cracked areas from behind while I was at
it. This was tedious, as the pieces are small, and you have to be careful
not to add material to spots that need to clear certain parts. (Like the
light bulbs for the marker beacon lights...)

The following afternoon it was time for the big test -- could I actually
drill this stuff without breaking the new "end" out completely? I first
carefully removed the strapping tape, and was surprised when it came off of
the new material rather easily. I then marked where the holes needed to go,
chucked the piece on end into my drill press, and EVER so carefully lowered
the spinning bit into the new plastic.

You can imagine how relieved I was to find that it cut through just fine.
The new J-B Weld plastic was just as strong (maybe stronger?) than the
original part, and I quickly finished drilling both holes.

It was a little spooky counter-sinking the holes for the screw heads, since
it meant hitting the piece with a fairly large drill bit. Again, however,
it held up to the drilling force just fine.

Upon reassembly, however, I discovered that my new end was JUST a tad
thicker than the original -- I had reinforced it a bit much. This didn't
allow the faceplate to mount on the audio panel chassis properly, so, using
the spinning bit in my drill press like a router, I carefully hogged out
tiny bits of the new material at a time, until it fit perfectly.

All that was left was the cosmetic touches. Using some flat black model
paint (J-B weld dries to a light gray color), I painted the new material to
match the original plastic. Since the repair is almost entirely on the side
of the faceplate, it's nearly impossible to see the new piece, and -- after
painting to match -- you can't see it at all.

I reinstalled the unit today, and it fits, looks, and works as good as new.
J-B weld is amazing stuff, and I'm $200 ahead because of it.

Now invest some of that money in a Dremel tool and I'd bet you'll be
able to literally sculpt your next J-B Weld project.

Got one. It's a great tool, but the drill press gave me a solid, spinning
cutting tool against which to push the piece, rather than the other way
around.

This difference gave me much more control over the cut.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Now it's time to fix all thos cracks in your interior plastic overlays I
used a similar type of plastic epoxy to fix my instrument panel plastic and
it worked great. I also was able to "re-cover" my right yoke with
Plasti-Dip and that too had great results. I was afraid that it would start
peeling after a year or so but it's still holding strong. Not as cold to the
touch as the powder-coated left yoke too.

Marco



"Jay Honeck" wrote in message
news:kOjTb.76216$U%5.412616@attbi_s03...
Now invest some of that money in a Dremel tool and I'd bet you'll be
able to literally sculpt your next J-B Weld project.

Got one. It's a great tool, but the drill press gave me a solid, spinning
cutting tool against which to push the piece, rather than the other way
around.

This difference gave me much more control over the cut.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"





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Now it's time to fix all thos cracks in your interior plastic overlays

Don't have any left!

Actually, there is one cracked piece around the windshield which is not
visible unless you stick your head up by the whisky compass. Every time I
do that (like, once a year) it bugs me, so eventually I'll replace it...

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"