Cracked plastics repair (was Re: First disassembly and rounded screw)

[Dan K]

On 2/17/03 "Edward Nilges" <nilges at hotpop.com>wrote:

>Hey all, I just opened up my 2400c for the first (and second time) for an HD

<snipped stuff>

>I found that one of the shells that hold the
>brass (?) nuts in the bottom plastic case was cracked. I'll probably replace
>that whole thing eventually, but it doesn't seem to affect the structure too
>much as the nuts seats in what's left of its shell, and its screw tightens
>sufficiently.

Such a PB case crack is a perfect application for ProWeld solvent. I've 
fixed a "Whole Bunch (tm)" of similarly cracked PB cases. One drop 
between the cracked bits, lightly clamped together overnight, results in 
a nearly perfect repair. I've used paper clips, clothes pins, a wrap of 
some fine copper wire, etc. to clamp the parts together.

It helps to have _all_ of the plastic, but if some bits are missing I've 
fabricated spare scraps from junked PB shell into suitable replacements. 
One good example is the ubiquitously broken hooks in front of a Duo's HD, 
a little straight bit of PB ABS plastic bridging the hook's remaining 
sides makes a fine repair. Any gaps between parts have zero strength, so 
the better the fit, the stronger the repair. Best case scenario has the 
original bits/shards/parts, which then of course fit together perfectly.

ProWeld is a solvent, very similar to the stuff used for 'gluing' ABS 
plumbing pipe together. I've not used the plumbing stuff on any PB ABS 
plastics, but the ProWeld is certainly cheap enough. I got several 
bottles for ~$3.00 each from Tower Hobbies, but I think lots of hobby 
suppliers carry it.

<http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LX0998&P=7>

I've become somewhat evangelical bout the darn stuff, I had given up hope 
of being able to repair PB plastics until I found ProWeld.  <G>  Oh, and 
once you have used it, you'll start looking around and you'll see all the 
other things around made of ABS and similar plastics with cracks to 
repair (eg: electronic equipment, appliances, automobile trim, toys, 
more, more, more...)

Dan K