Topics

TM500 series plastic face plate repair; solvents?


Dave Seiter
 

In the world of modeling and slot cars (and any other place styrene is used) there is a repair technique whereby one uses liquid styrene modeling solvent to "melt" scrap plastic into a goo that can be applied as a filler to holes, missing sections, or even build up new features that didn't previously exist.  Once the solvent outgasses, the new plastic can be worked the same as the original.  Slot car folks do this all the time, because kids were encouraged to "modify" their cars, leaving endless cut wheel wells in their wake.  A really good repair is almost invisible, but usually given away by dirt/slight discoloring in the repair.
Last night I was wondering if the same technique could be applied to all those broken corners on the TM500 plugins.  The plastic isn't styrene, and while the styrene solvent did dissolve the plastic, it became chalky and unusable, even the next morning.  
Has anyone experimented with this before?  Know what type of plastic was used?  It wouldn't be good for large missing sections (too much time involved), but smaller missing sections could easily be repaired if the right solvent was found.
-Dave


stevenhorii
 

I have repaired non-styrene plastic with a UV-cured resin called Bondic.
The kit comes with a tube of the resin and a blunt needle-type application
tip built-in. The opposite end includes a UV LED "flashlight". The stuff
cures very quickly on exposure to this light (or other shortwave UV
source). It is clear and needs to be used where the UV light can get to it
or it won't cure. The resulting plastic is hard and quite strong. I fixed
an ID card that cracked at the oval cutout for the neck lanyard. I
reinforced it front and back with pieces of clear plastic cut from a
typical semi-rigid plastic package. That repair has held up very well with
no delamination and despite some flexing of the card. To repair something
like a faceplate, if a small piece is missing, it could be built up with
the resin (best to cure it in "layers") and then sanded and painted to
match. A crack could be repaired from the back and then sanded down. Any
resin that gets into the crack by capillary action will cure when UV
exposed. I fixed a chipped piece of crystal this way - let the resin be
drawn in by capillary action, then UV zapped it. I built it up to bulge
above the surface and then once hardened. used a single-edge razor blade to
cut it down to match the underlying surface.

I admit to not having tried this on any plastic instrument faceplates, but
I think it might work given my experience.

Steve H

On Mon, Aug 31, 2020 at 2:56 PM Dave Seiter <d.seiter@...> wrote:

In the world of modeling and slot cars (and any other place styrene is
used) there is a repair technique whereby one uses liquid styrene modeling
solvent to "melt" scrap plastic into a goo that can be applied as a filler
to holes, missing sections, or even build up new features that didn't
previously exist. Once the solvent outgasses, the new plastic can be
worked the same as the original. Slot car folks do this all the time,
because kids were encouraged to "modify" their cars, leaving endless cut
wheel wells in their wake. A really good repair is almost invisible, but
usually given away by dirt/slight discoloring in the repair.
Last night I was wondering if the same technique could be applied to all
those broken corners on the TM500 plugins. The plastic isn't styrene, and
while the styrene solvent did dissolve the plastic, it became chalky and
unusable, even the next morning.
Has anyone experimented with this before? Know what type of plastic was
used? It wouldn't be good for large missing sections (too much time
involved), but smaller missing sections could easily be repaired if the
right solvent was found.
-Dave