Re: ATM Aluminum solder

["Peter D. Brooks" <pdbrooks@pacbell.net>]

UC007@aol.com wrote:
>> I do this all the time, and it works well. I generally use a product called
> "J-B Weld."
> It is a two part epoxy (A & B) system with a good filler. Joint fit up isn't
> as critical because, when the epoxy sets up there is no measurable shrinkage
> whereas polyesters shrink considerably. 

I've heard good things about JB weld.  

Checked with Machinery's, and the gap with epoxy is *not* critical
barring one weakness of the system:  Epoxy bonds are poor in peel
strength.  Ie, bond some plastic to your aluminum, and try to pry it
off, and the epoxy will let go.  OTOH, with a metal socket/tube
arrangement, you can get really good strength.  I haven't owned a
bonded bicycle, but it appears that the overlap for the tube to 
socket is about an inch.  I don't know the shear strength of epoxy,
but it should be good for a few thousand pounds, at least.


> It seems to me it will stand up to 250 degrees without weakening appreciably.

If memory serves, 150C is OK.

> Cost is about $5 for a couple of ounces, so you won't want to build a boat
> with it, but a little goes a long way. Like most epoxies you won't want to
> disturb the joint for at least four hours, and full strength is achieved in
> about twenty-four. 

You can also get various epoxies in hobby shops.  The general purpose
stuff is 30 minute epoxy, but 5 and 15 minute stuff are available.  The
really slow cure epoxy is more suitable for lamination than for
other joints.

Pete Brooks
--
Peter D. Brooks   
pdbrooks@pacbell.net
$INCLUDE "Witty saying"