From: Bill Morrow (penzance_at_gate.net)
Date: Mon Aug 07 2000 - 03:55:13 EDT
Ahh..
an expert.. :-)
well, one added point..
this epoxy repair worked extremely well..
it was to repair a hinge mounting point which had come apart due to the
hinge tightening up and tearing the kept nut from its plastic molded in
position..
this was a design flaw, which is a different case from a traumatic injury..
David Ross wrote:
> "epoxy resin and a little glass cloth is better and more permanent.."
>
> All-purpose solutions are rarely better than ones custom-designed for
> the problem.
>
> Resin adhesives are problematic on some ABS composition plastics, as
> they can have difficulty
> keying to the surface. Some epoxies will work somewhat on some laptop
> cases, depending on the
> epoxy and the particular model's case material.
>
> Solvent adhesives have been created for precisely this problem. The
> advantage of solvent adhesives is that they partly melt the plastic (to
> an imperceptible depth) and create a nice keyed surface; one can get a
> remarkably strong bond even if there are few contact points. However
> they are not as good as epoxy for filling big gaps, and might offer
> less structural integrity than one would get with a fiberglass
> reinforcement. They are also inferior in a mixed-material setting.
>
> Depending on the nature of the break, a combination of these techniques
> might be best (for example,
> solvent adhesive for the plastic-plastic contact points, with an epoxy
> gap fill, and glass cloth for reinforcement). However, if something
> like epoxy is used for the plastic-plastic contact then
> in fact the join will be plastic-epoxy-plastic, and susceptible to flex
> failure.
>
> Unfortunately, if Goop has already been used on the break, then it might
> not be safely reglueable
> with non-silicone adhesives. No matter how well you clean the old glue
> off/out of the break,
> it has contaminated the surface and other adhesives might not correctly
> adhere. (Epoxy is somewhat better in this regard, as the inferior
> epoxy/plastic adhesion makes it easier to remove than Goop.)
> On the plus side, Goop is a great mixed-material adhesive, so should do
> a better job than most on holding your chopsticks to your case:-)
>
> BTW, if it sounds like I'm obsessed with adhesives - it's true, an
> obsession which provides a great source of amusement for my wife. When
> I was younger I thought that it sufficed to keep white glue,
> epoxy, and CA glues on my shelf; now these are the adhesives I use
> least.
>
> - David R.
-- Happy trails...** Bill Morrow ** :-) WEB page http://thinkpads.com e-mail: bill_at_thinkpads.com, penzance_at_gate.net
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