Raising a bridge.

[Rex]

I have a bent top Martin copy with an ebony non adjustable bridge. I want to raise the bridge up about a quarter or maybe one half of a millimeter. Any advice?

[Bill Snyder]

Is it a glued-on, one piece bridge or is it lose or does it have a saddle insert?

[Dave Cohen]

All of the Martins I remember have floating bridges, similar to teens Gibsons.

First, remember that to raise the string height at the 12th fret by 0.25 mm, you will have to raise the bridge height by 0.5 mm, and so on.

It is hard to put material back on one-piece non-adjustable bridges. I have had some success with the following: With the brdige well sanded in, prepare an ebony shim of the thickness needed to raise the bridge height appropriately. I have done that with a drum sander. If you don't have one of those, you will have to use a block plane or a scraper. You can make a short-lived scraper from a new single edge razor blade by turning the edge over with the edge of a center punch used as a burnisher. Your shim should be slightly longer and wider than the bottom of your bridge base. Scrape the shim to the constant thickness you want (you need calipers for this). Then put glue on the bottom of the bridge base, place the shim on the glued surface, and use several rubber bands to clamp the shim tightly to the bottom of the bridge base. when the glue is thoroughly dry (preferably overnight), remove the clamps and use a block plane to trim the shim edges fluxh with the edges of the bridge base. When you are close, you can use successive grits of sandpaper to finish the job. If your gluing and clamping job was good, you will not be able to see the glue joint. If your thicknessing was done right, you should not need to re-sand in the bridge.

[dave17120]

I would agree with the last post, but I think the likelihood of your getting a perfect fit by pre-guessing the height is slim. So I would err on the safe side, and make it a bit thicker than you need (especially as you only think you want to raise it by half a millimetre, very fragile to make!)and then sand it carefully to your optimum height. I have done this a few times to save period bridges, and it works. Good luck, Dave

[fatt-dad]

Well this is quite a timely post as Dr. Dave is doing just this on my A3. (Hopefully, I'll see you tonight. . .)

f-d