bridge pin drilling quickie

[David Farmer]

Usually I use a long drill bit to clear clamps that are holding a backing piece.

Today I needed a different smaller size hole so I cross drilled the bottom stud on my bridge clamps for a 3/32" Hex key. The clamps are upside down with the long thumbscrew inside. Now I can use any regular jobber length bit. 

I thought it might come in handy for someone else. Cheers.

[Ned Knepp]

That's a pretty good idea. I can see where this could be handy in a lot of places... some of which have nothing to do with instruments repair.

[Christopher Parker]

I can't imagine a scenario where I would want to drill bridge pin holes with the bridge clamped to the top. My usual routine entails drilling the pin holes with my drill press. The high and low E string holes are only drilled halfway through so that small index pin holes can be drilled through the bridge and the top with the bridge clamped in place. This is where your clamp modification would come in handy for me. Thanks for sharing!

[David Farmer]

 Hey Christopher,  the bridge is already glued on. I do the same as you and drill the pin holes 90% through the bridge on the drill press. What I'm doing in the photo is drilling through the plugged top and  maple cap. The clamps are holding a backing block inside to prevent tear-out in the important area where the string balls sit. I know some people hold a backer with their hand but I like to have tight contact and drilling towards my palm while pushing into the bit gives me the willies's!

[Christopher Parker]

Okay. That all makes sense. I just hold the backing block in place, but I like the idea of clamping it in place simply because a clamp can hold it more firmly than my hand.

Just as a side note, while epoxy is (justifiably) frowned upon for many repairs, this is a case where I do feel that epoxy is the best glue for the job. Good quality epoxy that is properly mixed will dry very hard, and therefore works well for filling the voids that have torn out between bridge pin holes. Your pic is a good example as to why it's a good idea for the grain of a bridge plate (or bridge plate reinforcement) to be perpendicular to the grain of the top (another bit of wisdom I learned from Frank). Doing it that way prevents the cracks and missing chunks of wood between the pin holes. You're obviously hip to that, since you've oriented the grain perpendicular, but I thought it was worth mentioning just in case someone reading this was not.

[Roger Häggström]

...and with the solid unslotted string pins the new bridge plate will hold much better :-)

[Joshua Levin-Epstein]

When I grow up I want to do work that clean.

Christopher,

You mean parallel (the same direction) to the grain of the top. The original was perpendicular. But we know what you meant.

David, aren't you going to reinstall the sheet metal screws, to keep things looking original? 

[David Farmer]

I don't always run the patch that way but these ladder braced LG's with plastic bridges are seriously compromised in the north south axis. Especially with a spruce patch and a rip in the top connecting the holes.

The pictures are from a few different instruments. Sometimes I wonder when the last plastic bridge will be gone. There seems to be an endless supply.

I agree high quality epoxy is tough and gap filling but I avoid it on an any instrument that might be worth fixing again. That way no one has to train up mice to go in there with angle grinders.

I plug the holes and fill the remaining gaps with a Hide glue/wood dust "putty". It does a good job solidifying the mess and the cap will stick to it nicely. 

"David, aren't you going to reinstall the sheet metal screws, to keep things looking original? "

:-)

People generally bring things to my shop when "original" isn't working so well. :-)

 

[Christopher Parker]

Oops... Yes. Parallel. That's what I meant...