First build - back not properly attached

NotThePainter · Nov 24, 2019

Hello all!

I'm building my first ukulele from the StewMac kit and things are going pretty well. Pretty well until last night!

I was gluing the back to the sides and one of my cross braces didn't fit into the notch so now I have a very small gap! I'm not sure what to do at this point. The back is held on with tight bond and I guess I could try and soak the back glue off but I'm fear that that would wreck the wood! Filling the gap with glue is gross but that's the only thing I can think off.

Timbuck · Nov 24, 2019

Oh dear ..looks like a hot pallete knife job...to remove the back.

sequoia · Nov 24, 2019

I think you can just enlarge the notch and/or thin down the brace end, carefully remove the dried glue and reclamp... This is why you want to dry fit all of your pieces before final glue down.

Sometimes building is a process of fixing problems and you have to be adaptable. Good luck and let us know how it went. And by the way, you never "soak" wood apart. Apply heat and use a separation knife to separate glued wood.

NotThePainter · Nov 24, 2019

Timbuck said:
Oh dear ..looks like a hot pallete knife job...to remove the back.

So A palette knife is something that painter's use, do I just keep a source of heat nearby and work it through the gap prying away? I have a wood burning kit with a knife blade but there's no way that that would work without burning the mahogany!

NotThePainter · Nov 24, 2019

sequoia said:
carefully remove the dried glue and reclamp... This is why you want to dry fit all of your pieces before final glue down. ... Apply heat and use a separation knife to separate glued wood.

How do I apply the heat?

And I did dry fit, twice! But alas, that was on the back side so I didn't see it. I'll be more careful next time.

sequoia said:
Sometimes building is a process of fixing problems and you have to be adaptable. Good luck and let us know how it went.

Fixing broken stuff is actually quite enjoyable for me!

Beau Hannam Ukuleles · Nov 24, 2019

Nothing to worry bout- just:
widen the notch to fit brace then use a clothes iron to heat the area up until the glue softens and closes the gap. Hole the back in place with tape as usual until glue re sets.

Rbee · Nov 24, 2019

Beau Hannam Ukuleles said:
Nothing to worry bout- just:
widen the notch to fit brace then use a clothes iron to heat the area up until the glue softens and closes the gap. Hole the back in place with tape as usual until glue re sets.

useful

i will keep this advice for a futur mistake ^^

NotThePainter · Nov 24, 2019

Beau Hannam Ukuleles said:
Nothing to worry bout- just:
widen the notch to fit brace then use a clothes iron to heat the area up until the glue softens and closes the gap. Hole the back in place with tape as usual until glue re sets.

Oh that's cool. The only clothes iron we have is 30+ years old and barely works, it doesn't even steam anymore. But I'll bet I can use my heat gun, carefully, to heat the area.

Uke-alot · Nov 24, 2019

NotThePainter said:
Oh that's cool. The only clothes iron we have is 30+ years old and barely works, it doesn't even steam anymore. But I'll bet I can use my heat gun, carefully, to heat the area.

I think you really want a working iron instead of a heat gun to do the repair. Lack of steam is a good thing. If you decided to remove the back (which probably isn't necessary) the heat gun could be used to heat up the pallet knife.

sequoia · Nov 24, 2019

NotThePainter said:
How do I apply the heat?

You can also use a heat gun to soften the glue a bit. I don't think you need to remove the back. Do as Beau says and you can fix this mess easily.

NotThePainter · Nov 24, 2019

Thanks all for your help!

I used various razors and knives to carve a bigger hole in the side brace and the cross brace dropped right in. I could get a thin knife in the gap and pry the back apart some, but I didn't want to remove the back.

I used the iron to warm up the wood, I guess the theory would be that the glue would soften and then reset. I guess I didn't 100% believe that so I also added more glue, using the box cutter blade to get the glue into the thin gap. I then used my father in law's real wood clamps not the rubber bands. I was pretty happy when I saw glue oozing out both sides of the newly clamped surface! I wiped that up of course. I then let it dry for more than an hour, my basement is cold, and it looks perfect! Here are some photos and thanks everybody.

And hey, nice helpful forum. I only came her because of my emergency. I'll go introduce myself and start a build thread. What a fun place!

NotThePainter · Nov 24, 2019

and the last photo

John Colter · Nov 25, 2019

Nice save, NTP! As others have said, part of the skill of instrument building is in finding ways of correcting things when they go wrong - which they will, occasionally.

Screw clamps, G clamps and the like, are very useful, but it is so easy to apply too much pressure when using them on a delicate structure. You obviously dealt with that carefully but it is still worth saying, for the benefit of others who might read his thread and think it is normal to use whopping great clamping devices.

John Colter

NotThePainter · Nov 25, 2019

ukantor said:
Nice save, NTP! As others have said, part of the skill of instrument building is in finding ways of correcting things when they go wrong - which they will, occasionally.

Screw clamps, G clamps and the like, are very useful, but it is so easy to apply too much pressure when using them on a delicate structure. You obviously dealt with that carefully but it is still worth saying, for the benefit of others who might read his thread and think it is normal to use whopping great clamping devices.

Thanks!

I was talking with a friend of mine who is employed as a restoration carpenter. He mentioned that if you over clamp a joint you can actually squeeze much of the glue out leaving the joint weaker!

John Colter · Nov 25, 2019

"you can actually squeeze much of the glue out leaving the joint weaker"

There is that possibility, but way before you get to that stage, with a ukulele, the structure is likely to collapse.

Don't ask me how I know....................

John Colter

NotThePainter · Nov 25, 2019

ukantor said:
"you can actually squeeze much of the glue out leaving the joint weaker"

There is that possibility, but way before you get to that stage, with a ukulele, the structure is likely to collapse.

Don't ask me how I know....................

John Colter

Oh no! I can almost hear an awful sound. I was carving a wooden flute years ago, walking down the hall to find a quiet room to tune the holes, and someone came in from the outside, a blast of winter air hit me and I felt it crack in my hand!

sequoia · Nov 25, 2019

NotThePainter said:
I then let it dry for more than an hour, my basement is cold, and it looks perfect!

Nice recovery. Keep in mind that the same thing can happen when gluing down the top. You don't want to go there again because the box will be closed and you can't get at it... As far as what John says about overclamping, so true! It is called a "glue starved joint" and they can be weak.

First build - back not properly attached

NotThePainter

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