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Bridge Re-Glue, Belly Reduction, Polyurethane Glue
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Author:  klooker [ Sat Feb 29, 2020 11:42 am ]
Post subject:  Bridge Re-Glue, Belly Reduction, Polyurethane Glue
My buddy has this Recording King that he got for free.

The bridge was lifting so he shot some polyurethane glue under it which held it in place but also glued the stings in place as a bonus.

Luckily he didn't clamp it so the glue was thick & I was able to saw & pry it off without too much damage.

Some chunks are missing but that doesn't bother me - I've glued in shavings of spruce on something like this before.
Attachment:
TopView.jpg


Some poly is on the inside too. Any ideas on how to get it off? I'm having trouble getting a chisel or cutting tool inside. Acetone?
Attachment:
InteriorView.jpg


This belly is what concerns me the most. I don't have the TJ Thompson belly reducer plates from Stewmac. Is there another way to address this besides removing the bridge plate?
Attachment:
SideView.jpg


Thanks,
Kevin Looker
Author:  Colin North [ Sat Feb 29, 2020 1:42 pm ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
Quote:
also glued the stings in place as a bonus.

I hate it when that happens pfft
Author:  Bob Orr [ Sat Feb 29, 2020 2:02 pm ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
I think you only way to get PU off once it is cured is mechanically by sanding or scraping. Acetone or any other solvent wont touch it. First time I used this on an outdoor woodworking project i got it all over my fingers and it turned black and I could not get it off with anything. Put a post on a couple of woodwork forums asking how to get it off and the only sensible answer Igot was "12 inch disk sander and 80 grit" !!!

It eventually wore off after about 6 weeks!

Good luck with this one. Bob
Author:  Glen H [ Sat Feb 29, 2020 2:16 pm ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
Kevin, that hump is weird. Does it go through to the bridge plate where it has a corresponding dip? Is the top laminated or solid?
Author:  klooker [ Sat Feb 29, 2020 3:36 pm ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
Glen H wrote:
Kevin, that hump is weird. Does it go through to the bridge plate where it has a corresponding dip? Is the top laminated or solid?


The top is solid.

There is a corresponding dip in the bridge plate too.

That ridge peak seems to be the bottom edge of where the poly had ahold.
Author:  Ken Lewis [ Sat Feb 29, 2020 3:55 pm ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
The strange hump is probably caused by the bridge peeling away at the back and over time string tension
would cause the top and bridge plate to buckle with that hump in the middle, me thinks. Bob is spot on with
regards to the poly. To me that hump needs to go.
Author:  SteveSmith [ Sat Feb 29, 2020 4:02 pm ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
Ken Lewis wrote:
The strange hump is probably caused by the bridge peeling away at the back and over time string tension
would cause the top and bridge plate to buckle with that hump in the middle, me thinks. Bob is spot on with
regards to the poly. To me that hump needs to go.


Yep, I've seen that hump before when the bridge comes part way off or was never glued all the way and then sits there for years. The bridge gluing surface needs to be flat before you glue the bridge back on.
Author:  Terence Kennedy [ Sat Feb 29, 2020 4:19 pm ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
Gluing the strings in cracked me up. I don’t know how you would fix that without working on the bridge plate.
Author:  doncaparker [ Sat Feb 29, 2020 4:21 pm ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
Gotta love the penciled in open string notes right behind the bridge.
Author:  klooker [ Sat Feb 29, 2020 8:26 pm ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
Terence Kennedy wrote:
Gluing the strings in cracked me up. I don’t know how you would fix that without working on the bridge plate.


Well, there's this (Dan's video explains it pretty well, & from what I understand, TJ is very highly regarded)
https://www.stewmac.com/Luthier_Tools/T ... ducer.html

The strings made be laugh too, after the initial "Oh Shi..." moment. Luckily they all broke loose without too much fuss except the high e.
Author:  Terence Kennedy [ Sun Mar 01, 2020 8:50 am ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
That’s cool. I had seen it but never watched the video. If you use it let us know how it works.
Author:  Hesh [ Sun Mar 01, 2020 12:36 pm ]
Post subject:  Re: Bridge Re-Glue, Belly Reduction, Polyurethane Glue
Give Dave a call he doesn't like the belly reducers and this one's belly is not bad at all and we would not use a belly reducer on it. Nothing wrong with a bit of a belly, this one is really not bad in our experience.

Preparing the bridge patch with a very sharp chisel and then fitting the bridge very well and clamping with HHG would be our approach. No belly reducer.
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