On Mon, 10 Aug 2009 08:23:43 +0100, "N_Cook"
wrote:
Thanks for some interesting ideas. I was thinking of using some expanded
aluminium, anchored into the aluminium, with a fresh drilled small hole or
two and small nut/bolts. To give a scaffold for epoxy to anchor onto. Also
underscore the plastic to give a bit of key. What is the function of
aluminium dust in epoxy, other than a colourant?
Epoxy is hard and brittle. Aluminum is soft an malleable. If you try
to drill and tap straight epoxy, it will usually crack. The aluminum
provides a cushion. You can buy aluminum filled epoxy at the hardware
store, but I've found that it doesn't have enough aluminum and is
mostly brittle epoxy. So, I mixed my own. The hard part was finding
the aluminum powder. I made some by destroying a grinding wheel and
grinding down a slab of dead soft (pure) aluminum. There are various
instructions on the net for making aluminum powder. One uses aluminum
foil run through a shredder, and then through a ball mill for 2 weeks.
No thanks. Anyway, use only as much epoxy as necessary to hold the
dust together. If sufficiently large volume, insert reinforcing bars,
such as a paper clip, into the mix for strength.
Something I haven't tried is to insert the matching (3mm?) screw into
the partial hole, cover it with grease or some kind of mold release,
and then build up the epoxy/aluminum/whatever material around it. When
it hardens, just remove the screw and you have an instant threaded
hole. The problem is that it has a weak spot guaranteed to cause a
stress crack at the screw hole.
To the others in the thread , if I wanted to get hints on (apparently , oftn
walletctomy) buying specific replacement stuff from e-bay or how to google I
wouldn't be posting repair queries to sci.electronics.repair which has the
word repair in the title. Why do you think I deliberately did not mention
make and model?
If you actually want to repair some item, the idea is to supply as
much information about the item and its condition as possible.
Minimalist postings are useful academic exercises, but often wander
badly in a futile attempt to guess your circumstances. More
specifically:
1. What problem are you trying to solve?
2. What do you have to work with? (Make, model, version, etc).
3. What have you done so far and what happened?
There's plenty more info that would be useful, but the aforementioned
are the essentials. Anything less usually results in guesswork and
topic drift. I won't speculate as to your motivations for
intentionally withholding useful information.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558