<VV> Re: Cooling fans

[ScottyGrover at aol.com]

In a message dated 8/5/2007 8:10:20 P.M. Pacific Daylight Time,  
mfrancis at wi.rr.com writes:

 
Hi  Scotty, 
If you’re really going to get into  this, I think you’re bound to find out 
that an aluminum pattern has to be made  larger than the intended final size, 
to account for shrinkage. So using an  original steel fan would yield a part 
that was smaller than original  dimensions. I think the pattern has to be 1.2 
times the intended final  size. 
I work in aircraft and automotive  composites and have been reading the fan 
discussion over the last week. It  occurred to me that making a mold of the 
original ’61 fan, top and bottom,  then duplicating the vanes in flat stock, 
would allow for a detailed, but  exact duplicate of the original fan assembly that 
would be much lighter,  especially if the laminate used was carbon fiber with 
a high-temp resin. A  carbon fiber assembly could be as little as ¼ of the 
present steel  weight. 
So, as you examine your options  tomorrow, consider this as an alternate way 
of getting the fan we need for  modern Corvair performance cooling. With 
composites, we can run as many vanes  as needed, at any angle desired, even curved 
vanes! A fixture can be used to  mill slots in the upper and lower shells that 
the vanes key into, and a  high-temp adhesive used to do the final assembly 
of all the  parts. 
Just something to think  about……. 
Regards, Mel  Francis 
Oconomowoc,  WI



Mel, it's been a long time since I dealt with resins; the only resin I'm at  
all familiar with is fibreglass-reinforced epoxy.  I had thought that (it's  
been a long time since I worked in a foundry) I would dip the original fan  
pieces (when the fan was disassembled) in something like liquid latex to build  
up the thickness before I used it as a pattern.  If you are familiar with  more 
modern resins maybe you could tell us how you would go about building up a  
fan from the original pattern in a way that each unit wouldn't be a  one-off.
 
Scotty from Hollyweird



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