On Nov 23, 10:34*am, Dave Nadler wrote:
On Nov 23, 9:43*am, JJ Sinclair wrote:

I cut the head off some old junk instruments to make a perfect
drilling jig. Have one cut off an 80mm and another cut off a 57mm
instrument. Add another from an altimeter so's you get the cut out at
7 o'clock and your good to go. Helps in arranging things on the back
of a new panel to see just where everything must go. Not all
instruments are created equal..............measure twice, cut once!
Cheers,
JJ

That's what I did. Tips:

Use some wing-tape around the flange until the shell fits tight
in the new hole, which centers it and keeps it from moving
while you're marking the holes.

Use a centering punch to make precise marks for the holes.

Also, a metal "hole reducer" from Aircraft Spruce will
work in a pinch.

Hope that helps,
See ya, Dave "YO electric"