Lowering a Fixed Bridge

[Mike Buesseler]

I am about to do some setup work on an old Gibson A model. The action (the bridge) is too high; I would estimate I'll have to lower it at least 1/8". This is a one-piece ebony bridge; a fairly substantial piece of lumber. I've fit a few bridges to archtops over the years. Sanding off the bottom is tedious and pretty exacting--at least for me. (I just combed Frank Ford's page for help, btw).

So, I'm wondering if there is anything wrong with me sanding the TOP of the bridge down, instead of the bottom? I know I'll have to recompensate and cut new slots, but this seems much easier than the other approach.

I searched here for an answer to this question, but as usual, I didn't find the answer I was looking for.

Any advice or opinions on this job?

(Btw, in a side note, there is some top sinkage on this mandolin--at least it looks like it compared to another old Gibson I have. If the top is, indeed, sunken slightly, how come the action is too HIGH and not too LOW, as my logic, at least, says it should be?)

[Paul Hostetter]

I'm wondering if there is anything wrong with me sanding the TOP of the bridge down, instead of the bottom? I know I'll have to recompensate and cut new slots, but this seems much easier than the other approach.

You're right, it is. That's certainly what I'd do. Taking material off the bottom also makes the bridge progressively shorter end to end, which is not a good idea.

(Btw, in a side note, there is some top sinkage on this mandolin--at least it looks like it compared to another old Gibson I have. If the top is, indeed, sunken slightly, how come the action is too HIGH and not too LOW, as my logic, at least, says it should be?)

Heh heh. Too many possible ideas to try and float in the absence of really being able to examine it. I assume the neck is solidly attached, etc. A lot of string tension for a very long time.

[mrmando]

Time to slap an adjustable bridge on it, maybe?

[Paul Hostetter]

That would be a lot more work (to do it right, rather than slapping on some unfitted, out of the box item) than adjusting the existing bridge. If your car needs brakes, do you slap on mag wheels?

[MikeEdgerton]

...If your car needs brakes, do you slap on mag wheels?

Only if you want it to look good in the accident photos.

[Gail Hester]

I put those one-piece bridges in the case and leave them there whenever I can. I prefer adjustable bridges and get them custom made a little shorter like the originals on the old Loar era Gibson's. I think they sound better, have a footprint where the corners do not dig into the madolin top, and they are...adjustable. That's how I roll.

[Mike Buesseler]

Thanks, everyone, for the advice. Paul--yes, the neck is fine, solid, straight. This is an A-1, but otherwise this bridge/pickguard looks exactly like your photo. I take your point about how removing wood from the bottom shortens the 'foot' of the bridge. But, if I take enough off the top (not sure exactly how much yet), won't that actually widen the top (saddle) somewhat? Just a hypothetical question, I suppose, since I don't really think that much wood needs to be removed. Besides, I like the adjustable bridge idea pretty well. This is not my mandolin, though; it belongs to a friend. So, I'll have to sell him on the idea, too. And, then there's that dang fitting the foot to the top part. Not my favorite job.

I still ponder my other question about the top sinkage and the string height. I think Bruce Harvie told me he (or someone) calls that top sinkage 'Gibsonitis.' I read some of that thread awhile ago. Something doesn't add up in the equation for me. Top sinks but the action gets higher?!? Huh?

[Paul Hostetter]

I take your point about how removing wood from the bottom shortens the 'foot' of the bridge. But, if I take enough off the top (not sure exactly how much yet), won't that actually widen the top (saddle) somewhat? Just a hypothetical question, I suppose, since I don't really think that much wood needs to be removed.

But it's easier to take a bit of mass away from the top of a lowered bridge than it is to stretch the base to cover the former footprint!

Besides, I like the adjustable bridge idea pretty well. This is not my mandolin, though; it belongs to a friend. So, I'll have to sell him on the idea, too. And, then there's that dang fitting the foot to the top part. Not my favorite job.

I don't think adjustable bridges necessarily don't leave a footprint, quite the opposite actually. But making them really fit helps minimize that. Maybe that's the solution for now, and you can just put the original in the case and hope for no bad marks from the substitute. The Cumberland 'lowboys' are pretty nice bridges.

It's always been counterintuitive to me that an adjustable bridge should sound good. In my experience, they don't sound better or worse than a one-piece, just a little different.

I still ponder my other question about the top sinkage and the string height...Something doesn't add up in the equation for me. Top sinks but the action gets higher?!? Huh?

I know. Weird, idnit? There are many forces at work. The top can be distorted but still be pushed up.

[Mike Buesseler]

But it's easier to take a bit of mass away from the top of a lowered bridge than it is to stretch the base to cover the former footprint!

Ah, I see your point now. This one already has a 'footprint' visible just north of where the present one rests. I suspected a possible overspray, but if so, it was done long ago. The finish is very crazed and looks original. I don't see anywhere near the number of old Gibsons that you have, Paul, but a lot I have seen seem to have had their bridges moved and left in place for long periods...perhaps a corollary to the sinking top conundrum?

I don't think adjustable bridges necessarily don't leave a footprint, quite the opposite actually. But making them really fit helps minimize that. Maybe that's the solution for now, and you can just put the original in the case and hope for no bad marks from the substitute. The Cumberland 'lowboys' are pretty nice bridges.

I think we'll go with the adjustable. Frank Ford has some excellent photos and descriptions of how he does it. I've done a few before, but I think I can benefit from FFs pointers.

This is such a great site! Thanks, again!