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Well, I had one of those moments Saturday night. I was gluing the bridge on #3, and noticed that it slipped about a mm off to the treble side. I thought it would be OK, and that that small of a difference might not even show. WRONG! I saw it, and thought it was OK? I don't know what I was thinking! Anyway, after checking it against the finger board which is already glued on, it is going to show on the treble side, with the string growing closer to the outside edge as it approaches the sound hole. I may check it with a string before I take it off, but right now it looks like I'll have more clearance on the bass side than the treble side. If it was the other way, I could live with it, but this may be backwards. Anyway, what's the best way to remove a bridge glued with Hide Glue. No pin. Hair dryer, iron, heat gun? Protect the top with tin foil and cardboard? Work wet pallet knife under the edge after heating?

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Waddy

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Hi Waddy,

Sorry to hear about your mishap. I'm sure you're aware of frets.com, but that's where I'd send you for instructions on removing a bridge. Frank's photo essays on this will help you more than my own attempt to describe how to do it.

I remember David Collins saying he likes to use a heat lamp, protecting the top with a mask that overlaps the outer edges of the bridge by a bit.

Maybe some other will chime in with some tips. The bottom line is that if you get the glue hot enough and watch your grain runout, you should be able to slide a knife under there pretty easily and lift the bridge off with no damage to the top.

Good luck!

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Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Thanks, Todd, I'll check Frets.com.

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Waddy

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There are people who advocate the 'hammer method'. You hold a block of wod firmly against the front edge of the bridge, and hit the block fairly hard with a blow that goes along the top, causing the glue line to fail in shear. This is taking advantage of the brittleness of hide glue. The trick would seem to be to gauge the force of the blow accurately: it needs to be firm enough to do the job, since a lesser hit might simply transfer enough force into the top to break wood. I will say that I've never tried this one myself.

I usually find it best to take HHG joints apart dry, with no heat. Again, you take advantage of the brittle nature of the stuff; wetting the glue joint softens the glue, and allows it to flex a bit, and it also softens the wood. For a bridge you need a thin bladed flexible knife or spatula. I use a kitchen knife that I have ground down to a very thin taper at the edge, but with the edge itself _not_ sharp. You want enough flexibility in the edge for it to be able to follow the glue line as it fractures, but not a sharp edge that will cut into the wood.

Most tops have at least some runnout, and this is a problem. Suppose the runnout is such that it dives down into the top from the back of the bridge on the bass side, and the front of the bridge on the treble. If you start to peel up the bridge from the back edge on the bass side, any top wood fibers that adhere to the bridge will tear dfown into the top, and once that process starts is tends to get worse. The obvious remedy is to start that side of the bridge from the front edge, and the treble side from the back. If you start with a corner of the bridge out at the wing, and work your way forward/back as indicated and toward the center, you can usually get the thing off without damaging the top.

The main thing is getting a feel for what the edge of the tool is doing. You can feel it when it stops breaking glue and starts splitting wood. Take it slow, and save the shot of booze or coffee for _after_ the bridge is off.

Many violin repair people say that running a bit of alcohol into the joint will weaken the glue line. Apparently it drwas the water out, and makes the gle line even more brittle. Again, I haven't tried this.

If you use a hot light bulb do be very careful and protect the top! I know this guy that actually charred a quarter sized spot on the top of one of his guitars with a light bulb! The bridge came off nice enough but as I recall there was a bit of consternation that day. It takes a lot less heat than you might think for sure.

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http://www.booneguitars.com
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I've never heard the hammer method recommended without first tapping a chisel in a bit around the perimeter. Although I've heard some reliable people swear by it, I'd be terrified to do it on a fresh joint. I tried it on my test body once. I wanted to save the top but it wasn't a big deal if I bunged it up. I wailed on that bridge pretty hard and finally gave up.

On a new guitar with a perfect finish, I'd rout most of the bridge off before heating. It's just too dang hard to get a bridge off and keep a perfect finish. Even if you can do it without denting the finish around the edges (no easy feat), you may open up a line in the finish along the top seam if you have to heat a full thickness bridge. I'd rather re-make a bridge than mess up a finish. If you're not trying to keep a perfect finish, then try to save the bridge.

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http://www.chassonguitars.com

Thanks for your answers guys.

I'm liking Todd's idea of using a small amount of hot water and a pallet knife, since it is glued with HHG. I have those things. I'm sure the main thing is to go slow and methodically.

Alan, I'm not sure I've got the cajones to use the hammer method! It sounds good though!

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Waddy

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I play safe and route mine off. Don't want to get the center joint or braces heated too much...
done in 2 mins.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

If it is one of your own guitars and you can duplicate the bridge, then you could just hand plane it off. It planes off quickly and easily. When you are almost done use a chisel to remove the last little bit. You could also route it off like Peter recommended. Same idea but quicker.
Why run the risk of loosening braces and the top joint. Just slap a new bridge on.

However, if you must save the bridge then I much prefer the heat method to the blunt force method. Just like any other step in guitar building or finishing, things can go bad in a hurry so go slow. Good luck.

I could make a new bridge, but this one is perfect, and it has an inlaid cap, simple, but it took time, on the tie block and it's an 18 holer. Takes me a lot of time to make one and get it right. I know I'm taking a risk, but seems like the hot water method should cause the least damage. I'm going to check with strings tonight and see where I come out, and if I have to take it off. If it's close enough, I may let it go. It's 1 mm at the edge of the board at the sound hole difference. I can see it, but, so far, I have only checked it with a rule, and roughly.

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Waddy

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Yeah before you do anything i would put both E strings on it and see for sure how they lie near the edges, if it is acceptable, you are done, bonus. If it does need to come off, i usually work them off dry, without heat. There are several ways to go about it as this thread shows, and pretty much every solution described is a workable "standard procedure" for someone, so it is really a go with your gut kind of moment. Running a little bit of alcohol in at the leading edge of the knife does seem to do something good when working hide glue, and it doesn't make the top all wet. Alan described what to watch out for when dealing with runout very well.

Has anyone ever actually done the "whack it with a big hammer" trick and won? It sounds like it might be good for a rush! (not that i plan on doing it)

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Jordan Aceto
Ithaca, NY

The bigger hammer method really sends chills down my spine. I build pretty lightly anyway, and I would hate to see the bridge section of the top, still attached to the bridge, sticking out of my de-humidifier on the other side of the room.

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Waddy

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Waddy, The one I removed had been glued on for more than a year. I used a separation knife, a heat gun, and a little water. I ran a tiny bead of hot water along the seam of the bridge, then heated the knife, not the bridge, with the heat gun, then slowly worked it under the bridge. It took a while and I did loose some fibers of the top to the bridge here and there. But it worked.

When I finished I had renewed respect for the strength of hide glue. Also, it's not nearly as easy to unglue with heat and water as advertised.

I'M SAFE! Bridge will not have to come off, thank goodness!

When I checked it with a pair of strings, everything lined up just right. Don't know why it looked so far off when using a straight edge. Not something I wanted to do, but wanted to be prepared, and was willing to do it.

I know how hard it can be, to get glue to release. I had to take the back off of #2, though it was glued with fish glue. But, I believe they are pretty much the same.

I did a brittleness test with HHG, Fish Glue, LMI White, and Old Brown Glue. It was very unscientific, but I allowed each to dry in a little plastic tub. Made sure some was up on the sides, where it would dry very thin. Anyway, after removing the hardened glue from the container, the Fish Glue was by far the most brittle. It broke up immediately like glass. Only bent slightly before breaking. The LMI White came in second. The HHG came in third, but in fairness, all three of these broke quickly. They were very close. OBG, remained pretty flexible. Sort of like thin plastic. You could bend it double over, without a break. I won't be using it for structural things. It is, however, pretty good for laying up marquetry, and bends very nicely. Disadvantage is drying time.

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Waddy

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