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  #1  
Old 03-04-2019, 04:59 PM
PeteD PeteD is offline
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Default Hide Glue for Bridge Install

I'm still a newbie with hide glue, but have really enjoyed using it for various applications on my most recent build. I'm thinking about making a run at installing the bridge (steel string) with hide glue rather than titebond or LMI's glue on this one.

I ran across a youtube video by Michael Thames for a classical bridge installation. He seems to advocate for spreading a thin layer of HHG on the soundboard at the bridge footprint and then letting that dry. It seems he then just applies the HHG onto the bottom of the bridge and then mates that per normal over the dried HHG on the bridge footprint. The video is not extremely clear, but I think this is what he is doing.

Does this make sense to pre-apply and dry on the soundboard and then just apply the HHG to the bottom of the bridge before mating and clamping? I know HHG will bond to itself, but didn't know if the two surfaces need to have the glue in a liquified state as you mate them, or if the liquified on one side against dried on the other side will be ok? If so, it makes me feel more at ease with the timing of the process before it starts to gel.

Thanks in advance!
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Old 03-05-2019, 09:14 AM
bostosh bostosh is offline
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Good Procedure, same for a lot of bonding applications.
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Old 03-05-2019, 09:32 AM
redir redir is offline
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I think that process is called sizing. I don't do it that way but I'm not one to argue with what works for Thames either.

Do you have a link to that video? I'm wondering if he uses heat in this process as well.
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Old 03-05-2019, 10:03 AM
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Rodger Knox Rodger Knox is offline
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The top soaks up more water from the glue than the bridge does, so may need a bit more glue. I paint the top, then the bridge, then mate them together and clamp. I don't wait for it to gel on the top, but I don't see that it makes a real difference. The hot glue on the bridge should reactivate the glue even if it's gelled. Heating up the bridge with a heat gun before you paint on the glue doesn't hurt.
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Old 03-05-2019, 04:57 PM
PeteD PeteD is offline
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Quote:
Originally Posted by redir View Post
I think that process is called sizing. I don't do it that way but I'm not one to argue with what works for Thames either.

Do you have a link to that video? I'm wondering if he uses heat in this process as well.
https://www.youtube.com/watch?v=fh-On-44yT0

This is a multiple part segment, but the point in question is at about minute 2:30.

Thinking further, I'll probably follow Rodger's plan and maybe just hit the soundboard footprint with a quick heat gun pass before mating. I'm just a bit nervous about missing the 'window' before the stuff starts to gel.
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Old 03-10-2019, 05:25 PM
PonchoFrancisco PonchoFrancisco is offline
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Interesting video. I remember reading (a few years back) about a cello maker who sized the top and ribs with hide glue, clamped them together and then used a steam-cleaner attachment along the joint to fuse the two parts. Perhaps further investigation is in order,

Brent
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Old 03-11-2019, 11:16 AM
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Quote:
Originally Posted by PonchoFrancisco View Post
Interesting video. I remember reading (a few years back) about a cello maker who sized the top and ribs with hide glue, clamped them together and then used a steam-cleaner attachment along the joint to fuse the two parts. Perhaps further investigation is in order,

Brent
That may have been James Condino, he's published the method in the GAL quarterly, but he was doing double basses. I've used a similar procedure for tops and backs of guitars.
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Old 03-11-2019, 02:00 PM
redir redir is offline
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Quote:
Originally Posted by PeteD View Post
https://www.youtube.com/watch?v=fh-On-44yT0

This is a multiple part segment, but the point in question is at about minute 2:30.

Thinking further, I'll probably follow Rodger's plan and maybe just hit the soundboard footprint with a quick heat gun pass before mating. I'm just a bit nervous about missing the 'window' before the stuff starts to gel.
Thanks for that.

That is interesting. I struggle to get everything clamped up under 20 seconds. That includes putting glue on the bridge and the top and then clamping up REAL FAST.

He seems to take his time.

HHG is probably a lot stronger then most of us think it is.

But I have seen problems with gelling. When I join tops for example. I will heat the top joints with a heating gun then apply the HHG to just one side, rum the joint together and then clamp it up. I use wedges to squeeze the two halves together. Then I take the additional step of blowing hot air across the joint in a manor PonchoFrancisco suggested above. One time I forgot to heat the wood both before and after clamping and there was a marked glue line down the center seam. The only thing I could think of was that the glue gelled before I was able to clamp it. So I sawed that one off and joined it again remembering the heat and no problems.

My fear would be that gluing a bridge down like that would create a similar issue. But obviously it works.
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Old 03-11-2019, 02:32 PM
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Frank Ford Frank Ford is offline
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Watch out for what the classical makers do. Their instruments have far lower string tension, so they often get away with a "rubbed" joint, even skipping the usual clamping. For maximum holding power, you want as little glue left in the joint as possible, so clamping right after applying is most likely the best procedure.

I heat bridges in the microwave to about 105F to allow enough time, but I still move right quick to get the glue on there and clamped up.

Don't forget that liquid hide glue is a perfectly good alternative in many situations - just be sure to get it before its expiration date. All the instruments I built from 1966-1974 were done exclusively with liquid hide, and as far as I know, there have been no glue failures.
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Old 03-12-2019, 06:55 AM
redir redir is offline
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Quote:
Originally Posted by Frank Ford View Post

Don't forget that liquid hide glue is a perfectly good alternative in many situations - just be sure to get it before its expiration date. All the instruments I built from 1966-1974 were done exclusively with liquid hide, and as far as I know, there have been no glue failures.
Well now that sure is interesting to hear you say this. There was just recently a discussion on another forum about the perils of LHG, Franklin in particular. I admit I hopped on the band wagon and suggest to the user that they should NEVER use LHG with the one caveat that about 25 years ago I built a classical guitar using Franklin LHG and this guitar became my camp fire guitar and was by no means ever treated well and I still have it today and it's still my camp guitar.

I probably got lucky with the date code when I bought it. Seems that is what most people suggest.

At any rate I had thought about mixing urea in my HHG to glue on bridges. I understand it looses a bit of strength but at the same time HHG is plenty strong.

Oh yes and others had mentioned Old Brown Glue as well which apparently is just HHG with urea.
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Old 03-12-2019, 07:20 AM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by redir View Post
There was just recently a discussion on another forum about the perils of LHG, Franklin in particular.
My experience with Franklin liquid hide glue was 100% bad: 100% of what I glued with it came apart as soon as the weather got hot and humid. Different bottles, different years. Even if it works some of the time, the amount of time and effort that goes into making a guitar would be sufficient that I wouldn't recommend the gamble.

I've had no issues with either Old Brown liquid hide glue or fish glues.
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Old 03-12-2019, 08:44 AM
mercy mercy is offline
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It makes sense to me to use a variety of glues. HHG for bridges and braces, yellow for most everything else, liquid HG for under the fretboard extension and labels, super glue for rosettes. Some people use epoxy for the fingerboard.
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