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I thought I read somewhere some were clamping bridges with gobars. Anyone?

I recall that the question was asked and quickly shot down.

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"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck

I've used the method...and successfully. But you must keep a jack and caul under the bridge plate to act against the force of the gobars. I ended up staying with the normal method ...but it's certainly possible.

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JJ
Napa, CA
http://www.DonohueGuitars.com

just say no!!!!!

Why don't you want to use clamps? If it is a dread or OM, which have a big soundhole and the bridge close to it, should be reasonably comfortable.

For my classicals I use a caul and props inside. The bridge is pressed by hand for a while until it starts to grab, then I put two pieces of square 0.8" stock on each wing with the other ends resting on the upper bout edge next to the FB, then put a bunch of heavy books on them. It works very well with a classical bridge but with a belly it wouldn't be so good at all. Regular gobars would be better, but you must put some heavy protection on the guitar top !!!

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I have another discussion at MIMF too and Art Abrahams has pictures of his neat set up for gobars. It looks pretty good.

Sounds like a bad idea to me.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

On slip of a go-bar on the top would make anyone think twice. I guess you would really have to protect the top well just in case. Although, clamps are really easy. Heck, you could even make a deep throat style clamp from hardwood, some 1/4" inserts and some all thread.

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I'm going to actually make a vacuum clamp to hold the bridge in place and keep it from moving around. Then I might make a vacuum press like the LMI bridge clamp to fit on top of the locating clamp. But I was thinking it might be faster to put the support under the bridge and use gobars then make the clamp. Heck just how much pressure do you need to glue on a bridge ? If I dome the bottom of the bridge for a good fit. We glue lining on with clothes pins don't we? And HHG will pulls the wood together as it sets doesn't it? I can controll the pressure by the size of the gobar can't I?
I'm not too sure as to how tight the vacuum clamp will hold onto the top as I'm waiting for the sealing tape to arrive from Joe woodworker along with some fittings. I'll be using a frig compresser so I have to wait and see how this vacuum works. But I'm still just brain storming at this point. I was talking with Bruce Dickie via PMs and I mentioned the gobars and he like I thought it might make for an interesting discussion. Bill M. at mimf also said he did it on a repair with cauls and wedges for inside support and it would have been pretty easy with one of the SM sissor jacks. (anyone made their own?) Abraham used the 1/4" fiberglass gobars with plastic end caps and it looked pretty safe. I'm just trying to get away from sliding metal C clamps in the sound hole. I can just see myself dropping one and it chipping the finish on the sound hole or scratching or denting the top. But that might be the way I go in the end. I'm just looking for other ways to skin the cat.
If the vacuum clamp holds good I'm also thinking I could make top plate with a groove for a router collar and make a saddle slotting jig to route the slot with the bridge glued to the top. Basicly the same as my clam shell jig that I use to cut the slot now. But that's another discussion maybe later.

Isn't the whole idea of shaping the bridge to fit the doming of the top an attempt to reduce the stresses a straight bridge might create during clamping? If so, why would you want to negate that by using go-bars? It seems to me that clamping a caul and bridge with the same 'doming' as the top would be the best way to minimize any gluing stresses.

I sometimes glue bridges with go bars:



Oh sorry you mean, when it's attched to a body!

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

It can be done. When I took Sergei de Jonge's guitar making course, we glued our bridges on using go bars. No jacks inside the guitars. Bridges were, of course, carefully fitted to the tops (which were domed to either 25' or 28', I don't remember which. If I recall, we used three go bars (large fiberglass ones that were rectangular in cross section), one in the middle and one on each wing. No problems. They've done many, many guitars that way in that shop. It's a valid method.

I use a vacuum clamp on my builds, and various deep throat clamps on repairs.

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Todd Rose
Ithaca, NY

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

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

Todd, I would say intuatively,that using a vacuum clamp would introduce the least stress.Having said that, I've played a de Jonge guitar which was fantastic! So maybe I should revise my thinking in this area.Thanks' for the info.

Well how much clamping pressure is needed with HHG or Titebond? That seems to be an important question don't you all think. Perhaps many are over clamping? I mean it seems like the top with it's arch and the bridge plate and with the wings resting over the X braces that the top should be able to take some pressure since it resist the string pull without exploding. So maybe once you know how much pressure you need then you won't need the jacks but I can definately see why using jacks at first won't be a bad idea, that is if you think that using gobars isn't a bad idea .

That raises another question for me. There is so much and so many stresses in a guitar is that really even an issue to be worried about? Maybe that bridge with a little stress in it acts as spring energy that will help but with ball ends anchored it seems to me that the most stess on the bridge is do to the saddle wanting to torque the bridge forward and not from the string pull wanting to pull the bridge off.

Put some little jacks on the inside to support the top, and it shouldn't be a problem.
No different from installing the braces in the sides and gluing the back to the braces and sides at the same time. You have to support the braces when you do that. Here is a simple support jack.

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Waddy

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Sound Clips of most of my guitars

Assuming the bridge is well-fitted to the top, I don't think it takes much clamping pressure. Exactly how much?

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Todd Rose
Ithaca, NY

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

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

Good point about clamping force...the best joints are those which have perfect joinery. Theoretically, if your bridge curvature was a dead match for the curvature of your top, you wouldn't even need clamps with HHG. I'm not quite there yet so I still clamp

Chris...out of curiosity, why do you feel that gobar bridge clamping is more appealing that the standard bridge clamping procedure?

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JJ
Napa, CA
http://www.DonohueGuitars.com

Well I had to add 1/2" to the rear of my bridge plate because of the pinless bridge and the way the ball ends are anchored as the pinless bridge was a deviation from the original plans and the bridge plate fell short. A good lesson learned as to have all that stuff worked out at the start. Well when I was gluing in the extra piece which was just curved to match the back of the bridge, using 5" C clamps (harbor freight @ $5) with a bottom caul it appeared to me to be a somewhat tricky precisure. First being careful putting the clamp into the sound hole with a caul attached to it I had to worry about scratching the edge of the sound hole and then alining the caul with the piece of plate double sided taped to the caul wasn't easy. It took quite a bit of fumbling and caution which got me to thinking there has to be an easier and quicker way when it comes to the bridge. Take it for granted that my technic isn't honed as this is my first acoustic as my past builds are resos and electrics (no bridges glued on there or top voicing). So it's probably my nature that when I find something that seems to be clumbersome for me or overly complicated I tend to think if there is a way I fix it to work for me. By the way I put a magnet on the plate piece with double stick tape in the center and put glue on it and reached inside and put the piece in place and centered it by watching the top magnet. Then put more magnets to each side. Then clamped it with a C clamp and top and bottom caul for a few minutes and the removed loosen the clamp removed the magnets and tighten the clamp up. Back to the point, first I thought of just making a vacuum press. Then there was the fact that with the pinless bridge I didn't have a pin hole to keep the bridge from moving while gluing it either. So I got to thinking and thought I could route the shape of my bridge like in my bridge jigs into some corian I have and make it a vacuum clamp to hold the bridge in place and then just slap some HHG in the template/vacuum clamp and pop the saddle in and put 3-4 gobars on it and be done. I figured I'd cut the clamp flush with the front of the bridge so that the clamp was opened and could be removed after the HHG/Titebond has set up some and I could clean it up. But my plans could change.