I'm a beginner, but I know what the big guys will tell you. So do you!
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| Question about an imperfect bridge http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10102&t=14348 |
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| Author: | Jim Kirby [ Fri Nov 02, 2007 2:49 pm ] |
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OK, here is a question that I fear I know the answer to, but I'll ask anyway. I have a bridge on a recently completed OM that has popped loose at the tail side, bass side wing corner. The bridge seems fine under tension, FOR NOW ... I'm toying with the idea of shooting a little hide glue under the corner with a hypodermic and reclamping, but ... also thinking that the joint is crap and the bridge should come off, get cleaned up and reglued. The existing joint is fish glue. What y'all think? Bridge off? Quick fix-up instead? |
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| Author: | WaddyThomson [ Fri Nov 02, 2007 3:05 pm ] |
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I'm a beginner, but I know what the big guys will tell you. So do you!
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| Author: | Hesh [ Fri Nov 02, 2007 3:15 pm ] |
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Hi Jim - I'm just a beginner too but if it were me I would remove the bridge. Explore why this happened and here are some possibilities: 1) Bad glue joint. 2) Surfaces not prepared properly prior to gluing. 3) Bridge not radiused to the top or the top radius changed do to RH and the joint was not good in the first place. 4) And this one I heard happened to some guy named Hesh1956 - the clamps when gluing were tilted forward and the back of the glue joint had no real clamping pressure. Any way once I determined and eliminated the cause, cleaned up both mating surfaces I would glue and reclamp. If you search the archive under "bridge removal" I am told that there is "one method" for removing your bridge that might be helpful to you. Good luck. |
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| Author: | peterm [ Fri Nov 02, 2007 3:20 pm ] |
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I'm with Hesh on this one....maybe the bottom of the bridge doesn't match the radius of the top. YOu better remove it before it comes undone and tears out the top while poping off.... |
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| Author: | Rod True [ Fri Nov 02, 2007 3:37 pm ] |
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How long did you leave the clamps on. I don't use fish glue but what I've read about it you need to keep the clamps on for longer than other glues. Maybe you did this right the first time though. Yup, I agree with the other guys. Remove the bridge, prep both surfaces properly and re-glue. |
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| Author: | Rod True [ Fri Nov 02, 2007 3:40 pm ] |
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Jim don't put the hide glue in and re-clamp. It most likely won't be a wood to wood joint and it would most likely fail again. |
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| Author: | L. Presnall [ Fri Nov 02, 2007 4:08 pm ] |
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Ditto...the peace of mind is worth the extra time and effort to remove and re-glue (AFTER prepping the gluing surfaces again)! |
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| Author: | Hesh [ Fri Nov 02, 2007 4:24 pm ] |
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I think that Fish Goo requires 24 hours clamping time and David Collins would be the resident expert to ask about Fish Glue. |
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| Author: | Jim Kirby [ Sat Nov 03, 2007 12:14 am ] |
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OK, OK, the reading in the 8-ball is clear!  
I have my 11 buck Tower Hobby heating iron, so it's time to put it to use. Fish goo doesn't give up easily, but at least I have a little bit of a corner to get some water under. I had the fish goo clamped long enough, certainly. I suspect it was probably more like uneven clamping load, like Hesh's case. I was using the LMI clampless caul, and wasn't real happy with how it sat on the curved top of my bridge. Hesh, you may be an amateur but you are about 10 guitars ahead of me. Thanks for the help and pointing to the archive discussion. Jim |
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| Author: | David Collins [ Sat Nov 03, 2007 12:40 am ] |
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Making sure it's a fresh, solid, well fitted wood to wood joint is about the most important part, with good even clamping pressure being a close second. And yes, I would certainly remove and reglue, like has already been decided. Fish glue is pretty heat resistant, so when removing a bridge I like to dampen the bridge while heating it. I prefer heat lamps over heating irons for bridges, so I can just repeatedly moisten the bridge with wet rag, effectively working a bit of steam in to the bridge joint as I'm heating it. I do the same thing with hide glue joints. I've only had one fish glue bridge joint fail on me, and that was a personal beater guitar that hastily fit and clamped, then tried stringing up about two hours after clamping. It peeled loose almost immediately at the back edge and wings, which hide glue wouldn't have done. For all practical purposes, fish glue is just as good as hide for bridges in my experience if they are well fit and properly clamped. That said, I've since switched back to hide glue on bridges, because a bridge glue up just doesn't need much open time, and the faster I can move to the next step or free up a set of clamps, the better. |
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| Author: | Jim Kirby [ Sat Nov 03, 2007 12:54 am ] |
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Thanks Dave - yes, fish glue really ties up the equipment with it's long clamping times. I can really see how that becomes an issue for someone working at this for a living - it has to at least double the overall time to assemble a guitar. For me, I'm lucky to be able to free up the time where I need the clamps or guitar for the next step, so it's a non-issue. (Bridge clamped for a week? No problem!) 
I'm more worried at the moment about the heat resistance. I had to take apart another fish glue joint a few months back, and it wasn't fun. But I understand that moisture is the key. |
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| Author: | Bill Greene [ Sat Nov 03, 2007 2:16 am ] |
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[QUOTE=David Collins] Fish glue is pretty heat resistant, so when removing a bridge I like to dampen the bridge while heating it. I prefer heat lamps over heating irons for bridges, so I can just repeatedly moisten the bridge with wet rag, effectively working a bit of steam in to the bridge joint as I'm heating it. I do the same thing with hide glue joints.[/QUOTE] David, you're a busy guy and this probably isn't possible, but could you either explain (or maybe shoot a photo) of "how" you use heat lamps to get the bridge hot enough to create steam with the water, without doing some degree of damage to the surrounding top/finish? I don't doubt you, I've just never seen it. Thanks. Bill |
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| Author: | David Collins [ Sat Nov 03, 2007 3:29 am ] |
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Cardboard, tin foil, HVAC metal tape, and a 250w heat lamp. I prefer the heat lamp over hard electrical heaters because I feel it easier to control. The heat is relatively evenly distributed through any dark surface, and you don't suffer hot or cold spots from uneven contact with a metal heater. I cover a cardboard mask with aluminum foil, and tape over the bridge about 1/8" in from the edge with metal tape. If you want to keep heat away from anything like inlays you can just cover them and their surrounding area with reflective tape. As to the steam, I'm not really generating a huge amount of real steam. I will generally just wet the surface with a wet rag every 30 seconds during the 3 minutes or so of heating. Most of the water steams off in to the air, but enough seems to work it's way through to help at least a bit. Without moisture, fish glue will heat much like hide glue, seeming to crystalize a crack apart more than softening like PVAs. With this method it does seem to soften a bit more than with dry heat. |
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| Author: | David Collins [ Sat Nov 03, 2007 3:32 am ] |
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| Author: | Bill Greene [ Sun Nov 04, 2007 7:18 am ] |
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Thanks greatly David...I haven't seen that before. That's a neat way of doing it. Bill |
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| Author: | Hesh [ Sun Nov 04, 2007 8:17 am ] |
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[QUOTE=Bill Greene]Thanks greatly David...I haven't seen that before. That's a neat way of doing it. Bill [/QUOTE] I agree Bill buddy - and no tan lines either........ |
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| Author: | L. Presnall [ Sun Nov 04, 2007 10:04 am ] |
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Wow David, that's cool! (Well no, but you know what I mean! )...thanks for sharing!
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| Author: | Jim Kirby [ Sun Nov 04, 2007 1:09 pm ] |
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Thanks for all the advice. I would have liked to get to the job this weekend, but I was more preoccupied getting the bridge on for the first time on this one ... 
Still have a lot of cosmetic work and fp'ing to go yet. |
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