Tip: Hole-Matching for Awkward Sizes

[David Paule]

This worked for me for drilling a panel (not mine) to match the mounting plate of an instrument. The plate had nutplates attached to it.

My transfer punches are in fractional sizes so they didn't fit.

I found a number drill that was a very good fit. I sent the panel's owner out to the hardware store to buy me a replacement drill bit, and cut the flutes off the drill with a Dremel cut-off disk. This left me with a short smooth stub. That went into the drill press and I put a shallow point on it.

Presto! A custom transfer punch.

I had to go over these rather shallow punch marks with a deeper punch but that was no big deal. Then with the locations very well defined, the owner drilled the holes.

The mounting plate fit perfectly.

Dave