Advice needed: classical bridge string holes poorly drilled

[Kim de Rijke]

Hello,

I'm new to building and, perhaps as a result, I drilled some pretty poor string holes in my classical ebony bridge yesterday (these are the ones that are on a slight angle). The result is that 4 of the string entry holes (that is, where the drill bit exited on the inside of the bridge block) are low, though the holes are still spaced correctly and are of sufficient width. I have no photos (and would be embarrassed to post them anyway ) but what should I do? Should I try to fill them and re-drill (and if so, how to fill) or will this error be largely aesthetic without a significant impact on the quality of the sound? Thanks for your advice.

Kim.

[woodrat]

Kim, perhaps it is serendipity.....I would be looking for a lighter wood than ebony for a classical guitar bridge....I have stopped using it for my Steel String guitars and if I was making a classical I would not use ebony.
TG explains why this is so important in.... "the book"

John

[kiwigeo]

I've done this a couple of times. In both cases I made a new bridge but I'm a bit anal about such things. Filling holes of this size is a bit of a pain in the arse.

A picture would be useful.....don't worry about stuff ups....we all make 'em.

[Allen]

I know when you're new to building you hate to toss out a piece of wood because of a stuff up. But really, it really is probably the best option in many cases. Trying to fill and re-drill will most likely mean that the new holes are going to intersect with the old ones at some point, and you're going to have nothing but headaches when that happens.

Get a piece of Indian Rosewood for a classical bridge. There's a reason that it's used more often than not.

[seeaxe]

When it comes to making guitars, I consider myself a beginner but making mistakes with bits of wood, well thats different, in that I am an expert.

So you wont be surprised to hear I have done a similar thing too. Happily it was not so bad that I needed to remake the (figured blackwood) bridge on my last classical.

I got around the slight misalignment at the entry (back) by routing a vee shapped groove around the bridge blank at the height of the holes. I set this groove at the height I wanted to leave at the edge of the bridge wings and went right round the back, the ends and along the wings at the front, then when I cut the spare off the wings, I had a very consistent line to work to. Incidentally, the groove (maybe 1.5mm deep, max) helps get the pesky string into the hole. The string holes dont quite line up, but you cant see that, just the groove.

Also next time, I will build a simple jig that I can rest the bridge blank in at exactly the right angle and then drill all the holes first using the pillar drill and a fence on the table, all to the same depth.

If you want to stay with your ebony bridge, you could consider routing a slot where the holes are, gluing in a piece of scrap, if you have it, then start again (and use a jig).
But it might be quicker and more satisfying to make a new bridge as everyone else suggests..

I struggle to see past the things I do wrong on my guitars. Others will marvel at your woodworking skills but if you arent 100% happy with the bridge, then it will probably be the only thing you look at when you pick it up to play.

Welcome the forum and good luck with your build!

Cheers

Richard

[Kim de Rijke]

Thanks guys, message clear and undoubtedly familiar to other beginners: buy a new piece of timber and start again. Ah well, so it goes I suppose. I'm determined to get this bridge right. Will post a pic of the guitar when finished.

Have a great weekend,

Kim

[kiwigeo]

Kim can you perhaps take us through your bridge construction process.

I drill my string holes first using a drill press and then rout out the channel between the tie block and saddle. My procedure is basically as described in Roy Courtnall's book on classical guitar construction.

[simso]

If the bridge is now fitted to the guitar, I would correct the geometry by first redrilling the holes squarely with the top, after this I would fit a new bridge plate underneath and redrill or alternatively patch repair the bridge plate and then redrill, after that simply use a set of overesized pins and sweet.

[kiwigeo]

If the bridge is now fitted to the guitar, I would correct the geometry by first redrilling the holes squarely with the top, after this I would fit a new bridge plate underneath and redrill or alternatively patch repair the bridge plate and then redrill, after that simply use a set of overesized pins and sweet.

Um it's a classical bridge....

[simso]

Whoops, got to read the post properly......

Brain in neutral,

[kiwigeo]

Whoops, got to read the post properly......

Brain in neutral,

Just don't cut any fret slots until those beers have worn off

[charangohabsburg]

The result is that 4 of the string entry holes (that is, where the drill bit exited on the inside of the bridge block) are low, though the holes are still spaced correctly [...]

If I read this correctly

2. A) the breaking angle over the saddle would be increased dramatically on some of the strings
   B) and/or there will be a problem passing the string through some holes because they get stuck at the exit "inside" the bridge
3. The bridge and its string holes seen from the lower bout looks just perfect

It really depends on how much the hole exits are off. If it only looks sloppy but there is not problem 1.B present you could widen the holes on the exit side (towards the saddle) with a needle file's point until all upper borders of the holes are aligned. No big deal.

If the strings would not exit the holes you can fill the holes using a mix of ebony dust and CA. Put a reasonable amount of that mix in a syringe (from behind, not sucking it up through the nozzle), hold the nozzle firmly against the hole and push the mix through it until a worm of that mix starts to exit on the other end. For re-drilling the holes not only use a drill press with a jig but also use a quality drill bit (they are stiffer than the chap ones, it really makes a big difference!) an allow to exit the debris after every 2 mm you advance.

The good thing with ebony bridges is that you won't notice the holes have been re-drilled.

On the other hand... it does not cost much more time making a new bridge than stuffing and re-drilling the holes (and I would make the new one of rosewood or similar, as suggested by others above).

[Kim de Rijke]

@Markus - thanks for that, but filling and re-drilling seems too much of a hassle to me and not worth the trouble in light of the fact that I chose the wrong timber to begin with.

@Martin - I make the bridge (and entire guitar) following Natelson and Cumpiano. It is the only time I have used the drill-press, with the only other machine in occasional use the Dremel. I hand-saw the main cuts on the bridge and chisel away the in-between parts. I drill the string holes at the very last, and will spend sufficient time making a proper jig next time, that's clear.

While I'm on the bridge and now anticipating rosewood rather than ebony I was wondering how this is properly filled before gluing to the soundboard. It seems to me working with pumice will be impractical (I'm planning a french polish), but then getting epoxy into the pores properly doesn't seem easy either, or am I wrong in all of this?

Thanks for all your kind suggestions,

Kim

[kiwigeo]

Kim, I drill the string holes first. The blank goes into a mini vice so its sitting square in the drill press and I drill the holes deep enough to go through eventual tie block plus a few mm extra. Drilling it this way you have less chance of the drill bit wandering. Also chuck the drill bit with as much of the shaft as possible in the chuck to reduce chance of the bit wobbling.

[charangohabsburg]

@Markus - thanks for that, but filling and re-drilling seems too much of a hassle to me and not worth the trouble in light of the fact that I chose the wrong timber to begin with.

Right, it is a bit intimidating when doing it the first time, which fully justifies to make a new bridge instead.
As ebony for a classical guitar bridge goes I also would not go his route, but never go so far to say it was the wrong timber for this. I believe there are almost no wrong timbers in instrument making, only wrong methods.