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Is this fixable? I was drilling the bridge for my latest bandura and I was trying something new - I was drilling before routing out the "rabbet" and didn't anticipate that the drill bit would wander so much once it was in the wood. I didn't know this was a problem until I took my bridge off a holding jig to drill the holes at the proper angle. It became really clear once I cut the step.

The first picture is of the lower strings where I used a slightly bigger bit that didn't wander. The second is where I used a 1/16" bit that did wander. The position of the holes is important because they create a break angle over the saddle. Too high and the non-played portion of the string will vibrate and that sounds like shnit.

I know that really I should re-do the whole bridge, but I've already sunk quite a bit of time in this fitting and shaping. Can anyone think of a way to salvage this? i.e. fill the holes and re-drill those couple of holes which are way out of whack?

The only thought I had was to cut a length of toothpick shorter than the hole and pound it in with a punch then fill the ends of the holes with dust and CA or something like that. Worry would be that toothpics are softer than EIR (supposedly what this wood is) and that CA dust will be much darker than the surrounding wood.

Any other ideas?

p.s. I bought this wood off of e-bay as EIR - the color don't look like EIR to me but I've not seen too much EIR in my travels. It does smell like it though.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

I would fill with CA and dust .. but to make the dust somewhat lighter .. mix in some maple or spruce along with the rw ..... colour to taste !!!

You want to start each hole with an awl .. that way the bit wont tend to wander as much. I woudl suggest using a 1/16 inch carbide router bit (I do this when doing FB side dots) as it wont wander or bend

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Router bit's a good idea! I actually used a center drill to start each hole (for those who don't know http://www.mini-lathe.com/Mini_lathe/Chucks/Back_plate/Center_drill_.jpg). All of that wandering is in spite of that. Because of the complex curves, I haven't yet figured out how to make an indexing fixture that will allow me to accurately drill the holes and suspect that maybe I moved the holding fixture once the drill had started.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Decided to just re-do it.

_________________
http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Good call, you'd never be happy otherwise.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.