Soundboard didn’t glue down completely...c@*#$&p!!

Paul Bouchard · Feb 13, 2019

This is my second build and the first with and outside form. I thought that some heavy weights would hold the sides down to the soundboard adequately but was wrong. If I put my desk lamp into the lower bout, I can see light seeping out from between beads of hide glue. The gaps are about wide enough that I can slide in the corner of a piece of tinfoil.

I'm wondering how to proceed. The plan is to have a few strips of purfling and plastic binding. I'd rather not risk removing it again

. Would it make sense to try to work in some runny glue and clamp it down properly? I’d like to try gap filling superglue sold by Lee Valley (Special T or Super T) because I’ll be super gluing the binding anyway. I’m thinking I’d tape off the soundboard inside the lining and then try a syringe to force it in from the outside. Would I regret that?

I’ll make some proper spool clamps now.

kratzmark · Feb 13, 2019

Another newbie here.

I'll be interested to see what the pros recommend, but I would just put some CA glue into the crack (try thin first since it sounds like a thin gap - then medium if that doesn't work) and sand it with 400 grit.

Provides a near invisible fix in my (limited) experience.

resoman · Feb 13, 2019

If you have enough glue on the gluing surfaces you can put clamps on the spot and use a heat source, like a heat gun, and gently heat the spot while clamped. Just be really careful with the heat gun so as not to burn your wood. A hair drier might work but I've never tried one. I have a small iron that tailors use to get creases out of garments and that's what I use. One of those irons that model builders use to heat Monokote would work too. Amazon has Monokote irons so you can see what they are.

sequoia · Feb 13, 2019

Paul Bouchard said:
? I’d like to try gap filling superglue sold by Lee Valley (Special T or Super T) because I’ll be super gluing the binding anyway. I’m thinking I’d tape off the soundboard inside the lining and then try a syringe to force it in from the outside. Would I regret that?

Yeah, I think that would be a mistake using CA glue. I think resoman's suggestion is good. However if you are going to put binding around the top, who cares if there is a gap because when you cut your binding ledge and bind it it doesn't matter that top wasn't glued down perfectly because the edge is gone. The only problem I would foresee is that the top might not be glued down flush to the the kerfed linings. I think though that when you glue in the bindings and perfling that the glue will fill those spaces if any. Hope this helps.

Paul Bouchard · Feb 14, 2019

Thanks for the replies.

My big concern is that there's not enough solid contact between the soundboard and the kerfed lining. I was leaning to the super glue because as sequoia was saying, I’ll be likely be flooding the kerfs with super glue when I apply the binding anyway.

I'd be able to take the top off pretty easily if it weren’t for the transverse braces being securely glued. I’d try the iron (have used it successfully on veneers) but with the top being nearly 2 mm thick, I worry about scorching it before the glue on the inside would melt. Also, I was hoping to be able to keep it in the form to avoid it shifting when the glue melts.

I guess I'll sleep on it.

sequoia · Feb 14, 2019

Hey Paul, by the way I use CA glue (super glue #10 from SMD) also for gluing in my bindings... I still think that if you are going to put on bindings than the issue of the top not being glued perfectly to the kerfed linings is mute. Not an issue. The top is going to be glued to the bindings and the bindings are going to be glued to the linings so everything is glued. Plus you have your transverse braces securely glued to the linings. Don't worry, that top will be secure and isn't going anywhere. Don't sweat it or do anything that is going to potentially cause a mess like trying to remove the top and reglue it. I really don't think this is an issue. It might look icky at this stage but after you cut your rabbet for the bindings all will go away. Sometimes we can make things worse by trying fix something that isn't really an issue. Been there, done that.

Paul Bouchard · Feb 14, 2019

Ok thanks a lot. I feel more relaxed about it now.

I'm thinking I may still put some hot glue into a syringe and squeeze a little in under the linings. I’ll be cutting the channels with a guage and chisel, so it would be nice not to be afraid of it suddenly pulling apart while I'm futzing around with that.

resoman · Feb 14, 2019

Cam clamps are definitely the ticket

ProfChris · Feb 14, 2019

What I do in this situation is:

1. Apply a clamp to the gap but don't tighten it.

2. Introduce a little moisture or hide glue to the gap if I can.

3. Heat carefully with a heat gun, pausing every few seconds to check with my hand how hot the wood is (note, don't hold the heat gun too close and point it elsewhere than at your hand!).

4. Once the wood feels pleasantly hot to touch (like a domestic radiator on low), tighten the clamp gently until I see the joint close and some glue squeeze out.

5. Remove squeeze out, relax.

Takes about a minute per gap.

Paul Bouchard · Feb 15, 2019

Thanks again for the suggestions. Looking at it last night, the gaps were more than I was comfortable going forward with and because I'm working in something like a solera, it was hard to get the heat down where it was needed to melt the existing glue for additional clamping. I ended up taking the top off with a palette knife and a heat gun.

Hopefully uke #3 goes a little smoother.

BlackBearUkes · Feb 15, 2019

[
So, why are you using hide glue to make a uke? What is it you think you are gaining? If you think it will improve the sound, it won't. It is just glue. I would suggest using Titebond red cap in the future.

QUOTE=Paul Bouchard;2130309]Thanks again for the suggestions. Looking at it last night, the gaps were more than I was comfortable going forward with and because I'm working in something like a solera, it was hard to get the heat down where it was needed to melt the existing glue for additional clamping. I ended up taking the top off with a palette knife and a heat gun.

Hopefully uke #3 goes a little smoother.[/QUOTE]

Paul Bouchard · Feb 16, 2019

Going by YouTube videos, it seems like tons of high end makers like yourself are using titebond, so no, I don’t have reservations about how it affects the sound. I've been using HHG in my other woodworking projects for a few years and like it. I don’t need a ton of paper towels to clean up and if I get it on my clothes, it comes out in the wash. I like that I was able to take this top off for a second attempt - it wasn’t the glue's fault, I just thought the joint looked closed when it wasn’t.

Paul Bouchard · Feb 21, 2019

Ill wrap this up for the sake of future novice builders - the main reason my glue joint was so poor was that I didn’t think to put the sides into the form when I was sanding the rims flat. When it was secured in the form for gluing, the shape changed just enough that no amount of clamping was going to matter. Seems embarrassingly obvious now.

On the second attempt it all glued down nicely.

sequoia · Feb 22, 2019

Yes, those "Doh!" moments. If it makes you feel any better, they continue to occur even as you gain more experience. That is what keeps it interesting. Always something to learn.

Soundboard didn’t glue down completely...c@*#$&p!!

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