DIY Bridge clamp

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RLangham98

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Has anyone here made their own bridge clamp for a flat top acoustic?

My thought was to take some hardwood 1x1”’s, put pads at both ends, bolt them each to a block of wood at the other end so that they can pivot, then drilling a hole through each about three inches away from the pivot, and using a carriage bolt, wingnut and washers to tighten the whole affair down.

Obviously it would be weaker than a traditional metal cantilever bridge clamp and also operate at a mechanical disadvantage, but I’m having trouble justifying the cost for a guirar that’s probably worth less than the clamp, and I don’t know how often I would use it afterwards. And I like making my own tools, it reminds me of things my dad used to make when he needed a specific tool he didn’t have.

Anyone have experience or a better idea?
 

guitarbuilder

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Has anyone here made their own bridge clamp for a flat top acoustic?

My thought was to take some hardwood 1x1”’s, put pads at both ends, bolt them each to a block of wood at the other end so that they can pivot, then drilling a hole through each about three inches away from the pivot, and using a carriage bolt, wingnut and washers to tighten the whole affair down.

Obviously it would be weaker than a traditional metal cantilever bridge clamp and also operate at a mechanical disadvantage, but I’m having trouble justifying the cost for a guirar that’s probably worth less than the clamp, and I don’t know how often I would use it afterwards. And I like making my own tools, it reminds me of things my dad used to make when he needed a specific tool he didn’t have.

Anyone have experience or a better idea?

Yep. Something like this although I have deep Harbor Freight Clamps.

This would be easy enough to make



 

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RLangham98

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Yep. Something like this although I have deep Harbor Freight Clamps.

This would be easy enough to make



Oh, I had only seen the deep cantilever clamps, I hadn't even imagined clamping it through the bridge pin holes!
 

Freeman Keller

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Has anyone here made their own bridge clamp for a flat top acoustic?

My thought was to take some hardwood 1x1”’s, put pads at both ends, bolt them each to a block of wood at the other end so that they can pivot, then drilling a hole through each about three inches away from the pivot, and using a carriage bolt, wingnut and washers to tighten the whole affair down.

Obviously it would be weaker than a traditional metal cantilever bridge clamp and also operate at a mechanical disadvantage, but I’m having trouble justifying the cost for a guirar that’s probably worth less than the clamp, and I don’t know how often I would use it afterwards. And I like making my own tools, it reminds me of things my dad used to make when he needed a specific tool he didn’t have.

Anyone have experience or a better idea?


I use standard bridge clamps but I have made special cauls for the inside, particularly for doing bridge reglues. It is made out of UHMW (cutting board material) which glues does not stick to (there is nothing more embarrassing that gluing your caul to the inside of the guitar). It has slots for 3/16 bolts that will go thru the outer pin holes, the slots lets me clamp bridges with different pin spacing. The 3/16 bolts align the bridge to old holes, I then put three traditional clamps on.

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After the glue has dried I can reach in with a box end wrench and hold the head of the bolt while I unscrew the wing nut on the outside.

Depending on the style of bridge I usually just put some little pads of wood to cushion the outside

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In theory you could just use the two 3/16 bolts to apply the clamping pressure but I get much better squeeze out with the deep clamps.

Edit to add, the bridge to top seam is the highest stressed joint on an acoustic guitar and I want it well made.
 

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using hot hide glue is a very good idea for this, but it means you have 30 seconds max to clamp it down, I like traditional luthier cam clamps for gluing bridges.
 

Freeman Keller

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using hot hide glue is a very good idea for this, but it means you have 30 seconds max to clamp it down, I like traditional luthier cam clamps for gluing bridges.
I use hide glue when it is correct - vintage instruments or if that was the glued used before. I have to really have my act together because of the short open time. Caul in position, clamps ready, heat the bridge with a hot air gun, glue pot hot and ready

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The rest of the time its AR glue and a little less stress
 

RLangham98

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@Freeman Keller Oh that's lucky that you bring that up again! I just found my old cutting board of that material, which I haven't used in ages. I'll use that to make a caul. May end up just having to bolt the clamp together through the bridge holes. Luckily it's a twelver, so I have plenty of holes to choose from and can even have four in a trapezoidal pattern to distribute the pressure evenly.
 

RLangham98

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Okay so now I have a 5” deep C clamp from harbor freight, I have bolts wing nuts and washers that fit the bridge pin holes and I have a sacrificial cutting board for the cauls.

Is titebond III acceptable? I only ask because I already have gallons of it and probably nothing else at the moment. If not I can make a trip to Ace.

Edit: Cauls, not Gauls. Now, if I was Julius Caesar maybe I could do something with Gauls…
 

Soapbarstrat

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I made one a long time ago, but use it very seldom. Acoustic projects always get put on the back burner.
 

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guitarbuilder

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So did they compromise the strength of III to make it waterproof?

In instrument building, the general consensus is to use adhesives that can be undone more easily. Hide glue is considered the best for parts that need to come apart for repairs like violins and such. Yellow glue is considered by many to be an easier alternative on wood to wood bonds. I'm sure titebond ll and 3 would do the job but the next guy doing a repair on it might not be as happy as if you use original. That's just my opinion and your mileage may vary...LOL.
 

RLangham98

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In instrument building, the general consensus is to use adhesives that can be undone more easily. Hide glue is considered the best for parts that need to come apart for repairs like violins and such. Yellow glue is considered by many to be an easier alternative on wood to wood bonds. I'm sure titebond ll and 3 would do the job but the next guy doing a repair on it might not be as happy as if you use original. That's just my opinion and your mileage may vary...LOL.
It’s a very banged up guitar that will probably reach the end of its useful life with me (was being thrown away from a music store where it was used for lessons for 40 years), so I’m the only future luthier I have to be concerned about.

So I’ll weigh the difficulty of getting it off accordingly… will I still be interested in repairing this guitar the next time the bridge starts to come up, assuming that happens before something else fails?

I’ll think about that today and by the time I get off work I’ll have probably made up my mind.
 

Freeman Keller

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What Marty says about glues. In acoustic construction it is traditional to be able to take glued seams apart. Hot hide glue is the traditional adhesive for lutherie and it does come a part with heat and moisture. It is also a total pain in the rear rot work with.

Original Titebond (AR) will come apart with heat but not as easily as HHG. It is my understanding that TB III does not come apart period. I make it a point to think about someone who may have to work on one of my8 guitars in the future (reset the neck, attach the bridge) and I use adhesives that they would expect to find.

Test that I have seen indicate that TB I is stronger than most woods that you are gluing so its not a matter of strength.

HHG and TB I both clean up with water which makes the squeeze out easier to deal with.
 

RLangham98

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What Marty says about glues. In acoustic construction it is traditional to be able to take glued seams apart. Hot hide glue is the traditional adhesive for lutherie and it does come a part with heat and moisture. It is also a total pain in the rear rot work with.

Original Titebond (AR) will come apart with heat but not as easily as HHG. It is my understanding that TB III does not come apart period. I make it a point to think about someone who may have to work on one of my8 guitars in the future (reset the neck, attach the bridge) and I use adhesives that they would expect to find.

Test that I have seen indicate that TB I is stronger than most woods that you are gluing so its not a matter of strength.

HHG and TB I both clean up with water which makes the squeeze out easier to deal with.
Notably, all TB claims to clean up with water acc to their website. Haven’t had much of a problem in that regard since I’ve mostly used it on two part solid guitar bodies that I put through a planer after the glue has set. But here, it’s good to know.

I see your point. I’ll see if I can find original TB or other AR today, since I’m definitely not equipped for HHG.
 

Freeman Keller

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Notably, all TB claims to clean up with water acc to their website. Haven’t had much of a problem in that regard since I’ve mostly used it on two part solid guitar bodies that I put through a planer after the glue has set. But here, it’s good to know.

I see your point. I’ll see if I can find original TB or other AR today, since I’m definitely not equipped for HHG.

You don't say if this is a new guitar or a repair,, I do both. For steel string acoustic guitars I glue the bridge on after the guitar has been finished (with classicals I finish over the bridge). However I also remove all the finish under the bridge's foot print so it is wood to wood with wood glue at the interface. That is one of the advantages of lacquer or French polish, it can be removed with strippers to get back to bare wood.

Most of the failures that I have seen have been guitars where the manufacture didn't do a very good job of removing finish before gluing the bridge on. In some cases the wood itself fails, usually fibers of spruce are pulled from the top, sometimes delaminating laminate tops. There are some photos attached, the simple fact is that detached bridges are the most common failure that I get to fix and I have fixed a lot of them.

With finish on the top but removed from the foot print I want good squeeze out onto the finished top. With AR (TB I) I can let it dry for an hour or so until the squeezeout becomes gummy and then remove it with a sharp chisel. I can also wipe it off with a damp rag, there might be a film of glue left on the finish, that buffs off. There will be glue in the pin holes, drill that out with a 3/16 bit and ream the holes to whatever taper your pins are.

Hope this is helpful, unfortunately I've got a lot of pictures of fixing bridges.

ps - I should add that classical bridges are almost always glued to the bare top and finished over when the top is done. They usually don't have pin holes which can make it trickier to position them. Some makers use small dowels for alignment. Classicals have far less string tension so there aren't as many failures
 

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RLangham98

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You don't say if this is a new guitar or a repair,, I do both. For steel string acoustic guitars I glue the bridge on after the guitar has been finished (with classicals I finish over the bridge). However I also remove all the finish under the bridge's foot print so it is wood to wood with wood glue at the interface. That is one of the advantages of lacquer or French polish, it can be removed with strippers to get back to bare wood.

Most of the failures that I have seen have been guitars where the manufacture didn't do a very good job of removing finish before gluing the bridge on. In some cases the wood itself fails, usually fibers of spruce are pulled from the top, sometimes delaminating laminate tops. There are some photos attached, the simple fact is that detached bridges are the most common failure that I get to fix and I have fixed a lot of them.

With finish on the top but removed from the foot print I want good squeeze out onto the finished top. With AR (TB I) I can let it dry for an hour or so until the squeezeout becomes gummy and then remove it with a sharp chisel. I can also wipe it off with a damp rag, there might be a film of glue left on the finish, that buffs off. There will be glue in the pin holes, drill that out with a 3/16 bit and ream the holes to whatever taper your pins are.

Hope this is helpful, unfortunately I've got a lot of pictures of fixing bridges.

ps - I should add that classical bridges are almost always glued to the bare top and finished over when the top is done. They usually don't have pin holes which can make it trickier to position them. Some makers use small dowels for alignment. Classicals have far less string tension so there aren't as many failures
This was an Ibanez PF5-12 that was strung quite heavily and then used and abused by students for decades. When they knew it wasn’t going to hold tension any longer they kept using it as a six string. It has very mild distortion of the top but mostly the bridge was pulling away. Steaming got it off quite cleanly, and yes, I think it had some finish under there. The area under the bridge has been coarsely sanded so there is definitely not any now!
 

Freeman Keller

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This was an Ibanez PF5-12 that was strung quite heavily and then used and abused by students for decades. When they knew it wasn’t going to hold tension any longer they kept using it as a six string. It has very mild distortion of the top but mostly the bridge was pulling away. Steaming got it off quite cleanly, and yes, I think it had some finish under there. The area under the bridge has been coarsely sanded so there is definitely not any now!

Probably needs a neck reset while you're at it.
 

Freeman Keller

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FWIW 12's are considered "lights" in the acoustic world. They pull about 165 pounds of tension which and electric player might consider to be a lot. A full set of 12's on a twelve string would be mediums and at concert pitch are somewhere around 350 pounds. Many of us who play acoustic 12 strings tune down a couple of semi tones which reduces the tension dramatically.
 
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