Official Luthiers Forum!

I've sent Bob Garrish a PM, but maybe someone can push me in the right direction in the meantime...

The bridges he did for the group order some time back came with small indexed bridge pin holes that were not drilled all the way through the bottom of the bridges. How should one go about drilling them to the full diameter and depth? Not with a brad point bit, I'd assume, but with a regular bit that will center itself in the indexed point?

TIA,
Ken

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Ken Mitchell
Durham, NC

That is what I would do Ken my friend and what I do when I make a bridge from scratch. It's probably over kill but I sneak up on the final hole size using a number of consecutively larger, non-brad-point bits so they can self center as you indicated. I also hold the bridge firmly but so that it can move slightly as the bit contacts the pilot hole to permit the self centering to happen.

I do the same thing for tuner holes and I also place masking tape in the exit area of the holes to help discourage tear-out.

Thanks, Hesh! I thought that I was probably on the right track.

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Ken Mitchell
Durham, NC

I messaged Ken when I got back in today, but if anyone else has an issue here's the response:

The holes on the bridges are 1/8" and drilled just shy of the bottom surface of the bridge. A 1/8" drill bit will square itself up in the hole (they're around 1/4" deep IIRC) and drill a straight hole through, a larger bit will use the 1/8" hole as a guide and should self-center if you hold the drill straight. You should put a piece of scrap underneath to avoid chipping out the back. From there, you need to ream them to fit the bridge pins you use.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services