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Message
Thanks for all the comments and suggestions. Hey Jim, that's
one funny looking firewall :-) BTW- the tubes on the cores that I got are
about 9/16" diameter for the largest one, so I won't be using either of the
factory tubes.
Wrap the end of the core with a few layers of soaking wet towel
while welding
on the fittings.
Thanks for all the
construction tips Lynn, particularly this bit about the wet towels. As
I've thought of welding these things, I couldn't help but wonder how much of the
factory core I would be un-welding in the process. How exactly are these
constructed? I assume they're brazed, and something of a lower temp than
welding??
The cores will have oil in them that circulates in the system
to lubricate
the compressor. Let them drain for a few days and the rinse them
out with ketone
or similar and then soap and water. Blow it out to get it as
dry as possible
before welding. If you short cut this step, be aware that the
jet of orange
oil vapor flame that shoots out of the proposed fitting holes
is about a foot
long and will blow your welding helmet clean off of your
head.
Another wise piece of
advice. I haven't looked for junk cores, but the problem I've found with
the new ones is that none of them are made the same. I had planned to do
plenty of practice on similar thicknesses of aluminum, and then try the new
core. If I screw up enough of them, I'll surely be looking for some of
those junk cores for more practice.
These things work well for water or oil cooling. They are tough as
nails.
(the GM stuff). If you have room, you can cut one side off of a
bulkhead fitting
and use the hex as a welding flange. Better for oil cooling
where the fittings
hose ends are going to be heavy anyway. For water service,
the AN fittings
and hose ends will be too big (dash 16 or 20) and too
heavy.
I thought about the cut off fitting,
but aluminum AN bungs are pretty reasonably priced, so I'll probably just use
those. With everything in place this afternoon, it looks like I have room
to use an AN-12 bung (remember, parallel cores) and 90 degree hose fitting,
so I'm leaning strongly toward going that route. As much as it pains me to
buy all that AN hose, it's really the "right" thing to do. I'm sure the
silicone hose is perfectly fine, but the more I can conform to "aircraft
quality", the less grief I'll get from all the people who look at
it. I think Tracy actually mentioned this as a significant downside
to using auto hose.
Mount the core in foam lined
brackets. Don't let anything rub against them
(but a foam seal
strip).
I have the cores attached
to the redrive plate with aluminum angle on top, and bottom. The idea was
to weld the angle to the cores, then bolt it to the redrive plate. I
hadn't planned to put any sort of rubber dampening, since the cores are very
solidly mounted (can't twist, or bend). Should I put a 1/8" or so
piece of rubber between the angle and mounts? That just doesn't strike me
as a good idea, but I'm open to suggestion.
Also, when mounting the cores to the
angle. I planned to weld the angle to the cores on top and bottom, but for
test fitting, I drilled and clecoed the angle to the end plates on the
core. With only 6 clecoes, this thing is VERY solid. I'm now
wondering if I couldn't just put about a dozen 1/8" pop rivets, rather than
welding the angle. I have to admit, that I'm thinking about easy of
replacement if one ever gets damaged away from home. Assuming I
keep a spare core with two AN12 fittings welded to it, all I'd have to
do to replace a core is drill out the rivets, then drill and pop
rivet the new core. This may sound paranoid, but I know that Ed and Finn
have both replaced leaking cores. I'm also thinking about lessoning
the chance of damaging a core by overheating it with the
torch.
Thanks,
Rusty (sure would be easier if
it was at home)
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