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Reglue Tone Bar Advice
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=54686		 Page 1 of 1
Author:  Slim [ Tue Jan 11, 2022 3:57 pm ]
Post subject:  Reglue Tone Bar Advice
Either my eyes deceived me, something moved, or gremlins are in the house. So night before last I glued up x braces & bridge plate on my top everything went well. Last night I glued up the utb & tone bars, I made a few dry runs everything seemed good so proceeded with gluing up and everything looked fine after it was all clamped. I went to bed then woke this morning to admire my work and I see one of my tone bars on the very tip on the x brace side may not have closed up like I thought. I don’t tuck under the x brace like some.

I’m going to look at it again when I get home from work but I got a feeling I’m going to have to redo it. I used HHG so that will make it easier but dang I’m bummed. In the event I have to do something if it’s just last 5/8” that didn’t draw down on the tip would you remove the whole brace or just try cleaning under it and working some glue under it and re-clamping, or would you just start over with it? My concern is I don’t want to get crazy with heat trying to fully remove it and disturb some other area like the x brace it against, but I also don’t want to complete the build and have future repair built in. I guess hot knife might be the way but heck what do I know that’s why I’m seeking advice idunno. By the way this is a personal instrument not something for a customer. I’m just aggravated about it.
Author:  bobgramann [ Tue Jan 11, 2022 4:48 pm ]
Post subject:  Re: Reglue Tone Bar Advice
If at all possible, I would just wet the loose area, heat it from the other side with a hot iron, and reclamp it. The HHG will reactivate. Put a paper towel between the iron and the spruce top. The spruce may release some resin under the heat. With some luck, the towel will pick it up and minimize the stain on the top.
Author:  doncaparker [ Tue Jan 11, 2022 6:15 pm ]
Post subject:  Re: Reglue Tone Bar Advice
Can you post a photo? How you go about the repair is going to depend on the details, and those are hard to convey with words alone.

You don’t have to clean out the prior glue when working with hot hide glue. Just loosen what is there with heat, add more glue, clamp it better this time, then see how the repair worked after it all dries. But your concern about undoing more joints than are in need of repair is a smart thing to be concerned about. Let’s see what a photo can show us about that potential problem.
Author:  Slim [ Tue Jan 11, 2022 7:39 pm ]
Post subject:  Re: Reglue Tone Bar Advice
I tried to take a pic but I can’t get a good angle I will post the best one. I think it might possibly be ok I laid the top down on the work board and had the wife get eye level with the suspect joint while pushed down and released several times and she could not detect any movement nor count I when holding it in the air doing the same.

I think the brace have a slight distortion or twist I did not realize and it maybe playing a trick on my eye. I thin I may just warm it on the end and clamp overnight and then see. I’ve started rough shaping the braces getting ready to start scalloping and it seems pretty solid.
Author:  bobgramann [ Tue Jan 11, 2022 7:56 pm ]
Post subject:  Re: Reglue Tone Bar Advice
Look carefully at the next one, too. Try to slip a .001 feeler gauge under the brace. The brace and top have to fit tight all along the brace footing. If the foot is uneven, it will be worth your time to plane off the brace and try again. Any gaps in a HHG joint will haunt you later. You will see unexpected distortions in the top when you string it up. It will be much harder to fix then than it is now. But, if the brace footprint is perfect, then wetting and reheating it and clamping it shut will take care of it
Author:  Slim [ Wed Jan 12, 2022 12:24 am ]
Post subject:  Re: Reglue Tone Bar Advice
So what I decided to do was place it back on the work board with shim ( I don’t use a radius dish ) and lightly clamp the x braces on the south ends and place a clamp carefully with a very very small amount of tension at the center of the x brace hopefully accomplishing some stability in the event an area get warmer than intended in an undesirable place. I also chose to wrap the surrounding braces with foil and place towels strategically so that only the suspect joint was exposed enough for operation.

I chose to go with my wife’s pink blow dryer instead of heat gun in an attempt to keep from getting to much heat. I heated up the crockpot glue pot and go the glue 3 or 4 more degrees than I normally due and after giving the joint some heat I gave the area a shot of glue along the joint edge and tried to work some towards and into the area of concern with an old heated hacksaw blade while simultaneously running the pink blow dryer. I then clamped it up tight for the night. Time will tell I’m just disappointed In myself for not catching it last night, but the more I look at the picture and the more I think about it I think it maybe the very edge of the brace got rounded during sanding the radius so it looks like a gap but not . My feeler gauge set is in the shop but I tried to slide a a piece of paper under the brace but it would only go in about a hair’s width and I think that’s due to the rounded edge of the brace
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