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Date: Thu, 21 Sep 2006 10:02:39 -0400
From: Ernest Christley <echristley@nc.rr.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: finned aluminum sheets?
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Russell Duffy wrote:
> The corrugated heat sink was neat, and I had already tried to figure out a
> way to make that work.  I do have some of the miracle brazing compound that
> Ed found, and that would be perfect for joining the folded heat sink to the
> inside and out of the pan.  This may actually be the leading candidate at
> the moment. 
>   
Just a couple more thoughts I've had, Rusty.

Make the corrugated fin from really thin aluminum by weaving it through 
a stack of paint stir sticks, then drill 1/8" holes through it to 
increase airflow and surface area (lanced fin construction is what they 
call it).  Take some of the "miracle brazing compound and smash it 
flat.  I have one of the sheet metal working tools that would do an 
excellent job of it.  Put the brazing strip between the fin and oil 
cooler box and put a rivet at each corner to hold it tight,  then stick 
it in an oven to flow the brazing.  The brazing can be run perpendicular 
to the fins to guaranteed solid attach points.  The rivets may need 
extra brazing for a good seal.

Other thoughts:
The assembly might need to go in the oven at an angle so gravity will 
pull the brazing into the joints.
There will probably be issues with flux and subsequent cleanup.
The inside and out could be done at the same time.
Could the sticks be left in for the brazing operation?  It would depend 
on the flow temperature of the brazing material, I guess.