HP-2116A chassis (or repairing cast aluminum)

[Bob Shannon]

I think the actual frame here is magnesium alloy, not aluminum.

Any attempt to weld this might be spectacularly bad idea.

----- Original Message ----- 
From: "Pete Turnbull" <pete at dunnington.u-net.com>
To: "General Discussion: On-Topic and Off-Topic Posts" 
<cctalk at classiccmp.org>
Sent: Saturday, April 16, 2005 8:20 PM
Subject: Re: HP-2116A chassis (or repairing cast aluminum)


> On Apr 16 2005, 16:33, Tim Riker wrote:
>> The HP-2116A in my haul yesterday has a broken chassis:
>>
>> http://rikers.org/gallery/hardware/20050416_120314
>
>> 3) Thoughts on repairing the chassis? I could bondo, superglue,
> epoxy,
>> silversolder, etc. the pieces together, and add a plate behind it
>> attached with countersunk screws. Would not be very visible once the
>> panels are put back. I have the two side panels and the bottom panel,
>> but no top panel. Thoughts on which would work best?
>
> Glues aren't going to be effective at all, and you can't silver solder
> aluminium.
>
> It's possible to TIG weld aluminium and that might not be expensive if
> you know someone who has a TIG welder (they're often found in small
> engineering shops and car body shops).  It's also possible to MIG weld
> aluminium, but TIG is more common and tends to give better results in
> my experience.
>
> If you want to try it yourself, there are various forms of aluminium
> solder, but most need special fluxes to cope with the oxide, they can
> be tricky to use (depends on the grade of aluminium, which is rarely
> pure, it's normally really an alloy), and not very strong.  They also
> need a lot of heat because aluminium conducts heat away extremely well
> (this is also one of the problems with MIG welding it).  Aluminium is
> often soft-soldered with a stainless steel scratch brush to remove the
> aluminium oxide under the solder pool, or done with an ultrasonic
> soldering iron (expensive -- I once nearly bought a *cheap* one for
> UKP300).
>
> For hard-soldering, or fusion welding really, the best stuff is
> Techno-Weld.  It really works, and you can get it in the States as well
> as in the UK:
>
>    http://www.techno-weld.com
>    http://www.techno-weld.co.uk
>
> One of the basic "kits" of rods would have all you need; they also
> include the scratch brush, abrading wire and instructions.
>
> Or just rivet or bolt an L-shaped bracket on each side.
>
> Whatever you do, be prepared to file a bit off the broken edges to make
> sure it fits back together; whatever broke it probably stretched and
> bent it too.
>
> -- 
> Pete Peter Turnbull
> Network Manager
> University of York
>