At 12:29 AM 18/01/2004 -0500, you wrote:
>  I have a Toshiba laptop with a crack on the lid by the hinge. I can't
>get the part to replace it. Is there a recommended glue to repair this type
>of plastic?

Jack, here is some material that I picked off the Thinkpad list some time ago:
*******************************************
Use the kind of solvent adhesive plumbers use - look for the stuff that is
good for both ABS and PVC plastic, or at least the ABS stuff.  This does a
remarkably good job provided the crack does not involve missing bits or gaps.
(I have a latch on an old 560 that has been repaired this way - since it is
a latch, it is often under substantial stress, and the last repair has
lasted over a year.)
If you have to fill gaps, then a 2 part epoxy is probably better, though
the actual adhesion to the case plastic is less than with the solvent
adhesive.  One possibility is to glue any bits that are in contact with the
solvent adhesive, then fill the gaps/reinforce with the epoxy.    - David R.
++++++++++++
Jack Mindy: A two-part epoxy fills in the gap once either or both pieces
has been distorted. If you do decide to fill in a gap, "JB Weld", a
two-part epoxy-type product is unbelievable stuff. Color is medium gray
when dry. Any hardware store has it. It has yet to fail me.

As someone has already suggested, the glue used by plumbers to connect PVC,
CPVC and ABS pipe might be a more desirable remedy, if only because it
doesn't leave an obvious lump of a different color. This type of glue
causes the plastic surfaces to swell and weld together. But be aware that
this stuff gives you about five seconds position the pieces before
everything is solidified. The fumes are pretty awful. The can it comes in
has a dauber built into the cap, but you'll probably want to use something
(non-plastic) smaller. It's rather thick, goopy stuff.

Allow me to suggest another possibility that may or may not work. Many of
us have learned from experience that "superglue" usually doesn't work on
plastics. However, liquid styrene glue works very well on many plastics by
melting and welding the surfaces, much like the plumber's glue. This stuff,
a thin, clear liquid, comes in a 1 or 2 oz. bottle with a small brush in
the cap. It's usually found only at serious model railroad shoppes (not toy
stores). It might be good if someone tried styrene glue first, since it's
the least "invasive". To test, just dab a drop on an unobtrusive spot and
touch it with your finger. If you leave your fingerprint in the plastic, it
might do the job.        +++++++++++++++
Bill Morrow: most thinkpad cases are carbon fiber..
acetone won't melt and thus bond these materials..
acetone is a solvent that is used as glue and as part of glue for model
assembly..
there are other glues that might do the same sort of job..
the PVC type glues i have not  tried for anything BUT PVC pipes..
thinkpad cases, when i have seen them break, usually break without
deforming.. thus two part epoxy glues should work..
especially if some glass or other fiber can be used on the back side to
create some substance that will strengthen the part..
i'm not sure what the keyboard bezels are made of..
++++++++++++++
David R: The carbon fiber is just reinforcing material for the ABS composition
plastic substrate, which is why I recommended (and use)
ABS adhesives. (The plumbing adhesives I discuss come in 3 versions: PVC
only, ABS only, and PVC+ABS.
I recommend against the first.  There are specialty ABS adhesives that are
likely better than the plumbing variety, but the latter is universally
available.)  I've never tried the styrene adhesive Jack suggested on a
laptop case.
The problem with epoxy is not strength - it is wonderfully strong - but
adhesion.  Epoxy is one of the least sticky glues there is, and has trouble
getting a proper bite on most plastics.  (By contrast, CYA adhesives like
superglue are
very sticky but lack strength, and will fail under torque.  Worse, it is
often the first glue people try on plastic, and when it fails it leaves a
hard-to-remove film which makes it even harder for other glues to
bite.)  However, it is miles better
than the ABS adhesive when there are gaps, since the latter is designed for
flush surface-to-surface contact.
***************************
HTH




Robert Turnbull, Toronto, Canada

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