> Paul:

 Jerry Hey tells me it's nearly impossible to weld 1/2" aluminum.
 So I redesigned this left side engine mount, welding the 3/16
 thick pieces out of steel, and bolting in the 1/2" thick aluminum
 piece with 3.5" long 1/4 inch bolts.  Do you see any problem
 with this?  The aluminum part needs to be 1/2" thick or greater
 for the rubber isolation mount.

 Perry

Not impossible. Merely difficult. First of all you need a REALLY
BIG tig welder. Actually it is easier than Jerry thinks if you
warm it up to 500 F before you start welding. I have seen
plenty of 1/2 inch stuff done with a small 175 amp tig welder
by using this method. You will need a temp controlled oven
handy.

Looks great Perry. No problem with four 1/4 inch bolts in
single shear. Each single shear bolt location will take in
theory 7,000 pounds at 150,000 psi.

Paul Lamar

I beg to differ.  In the past week, I have made many welds in .5"
aluminum.  These were all with 800 to 900 degree preheats using
either a temp stick or soot as a temperature gage. With my Miller 250
Syncrowave set at maximum, in fillet welds, I was able to get good
root welds but the bead  peripheries were not blended.  Also, the
welds got colder as they progressed, indicating that the welder could
not keep up with heat dissipation in large aluminum plate.   Checking
with the Miller Rep, he said that I would need more than 300 amps
and my Lincoln welding textbook recommended even higher amperages.
Also necessary, in their opinion  a special torch with a 3/16"
tungsten. I have welded .5" aluminum using a root pass and then a
pass down each side to blend the fillet.  It looks good but we are
talking AIRCRAFT ENGINE MOUNTS!  My advice to Perry was exactly what
the Miller rep told me and what my experiments have shown.  Jerry
--
Jerry Hey

 
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