Wayne Walter Peterson wrote:

Hi Paul,

I am building a jig to make a motor mount to match my 13B to my Berkut.

I am useing 2X2 tube with 1/8 inch walls and 1x1 tube with 1/8 inch
walls.

Should I stress relieve the jig before I weld up the motor mount?

I screwed up and drilled the holes in the firewall for the IO-360/
motormount already.

I made my jig to have the 13B sit in the motormount in the same place
where the IO-360 would sit, I used the fore aspect of where the prop
sits to place the 13B.

Tracy's redrive in place.

Hung from the rafters over a copy of the firewall.

The Berkut can use a IO-540 but if a large prop is used, it can hit the
ground with the nose high.

I used 7/8 4130 tube with 0.058 wall for most of the mount, there is
some 5/8 wall with 0.058 wall as well.

I have a plate of 3/8 inch Al 6061-T6 between the mill and the oilpan
simular to Tracy's mount.

I have rubber isolators at four points that are in the Al.

I will use TIG to weld up the 4130 and stess relieve it while it sits in
the jig.

I have someone helping me with the welding, he has worked at Harley in
Milwaukee for 32 years.

He notes even with the jig I am making the motor mount will change it
shape when it is being welded up!

He said after it is welded, and if is not right, we can bent it where we
want it.

He said they do it with the Harly frams as well.

Wayne Peterson

It won't hurt to stress relive the jig. If you don't it might stress relieve 
itself as it gets heated in the process of using it to weld the mount itself. 
That might result in a bit of moving around of the hard points. 
Your friend is right about the mount moving after it comes
out of the jig. Perhaps sticking the whole rig in a large
oven would help.

I drilled the mounting holes in the composite firewall after I welded up
the motor mount.

Got any pictures?
We love pictures of these sorts of things. Helps all of us design
our unique jigs for each different kind of motor mount.

Paul Lamar
 
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