When we left our
vintage old Gibson A-4 mandolin, it was waiting for yours truly, the awful of this blog, to cook up a caul to use to press down the side to fix a crack.
Let's get with it, shall we?
The top of the mandolin is lower than the fingerboard, so I'm making a caul with a triangular section of a wood block cut out to allow it to sit on the fingerboard, but also have a part that also sits on the top - basically two levels at once.
Since I don't have a bandsaw, I used the jamb saw to make one vertical cut for the long side of the triangle.
You might see where this is going.
I thought I'd want pressure on both surfaces when I clamp it up. Pressing down on the fingerboard alone doesn't close the crack on the side much.
So I glued some cork to the bottom surfaces. You can see that, ironically, I used another caul to help clamp the cork down.
I'm also going to round the edges a bit more...it looks more finished and not so crude that way.
I actually like making cauls. You get to be a bit creative and use the problem-solving part of your brain at the same time.
If you're wondering about that bad spot on the side, well, I did sand that smooth later.
You can see that there will be pressure on both the end of the fingerboard and the top, which we need in order to close that crack on the side up as much as possible.
Now back to our crack repair.
The plan is to warm up the crack a bit with the heat gun, to give a little more working time with the hot hide glue.
Then I'll hold the crack open with the spatula, get hot hide glue into the joint, then clamp it up.
Good luck to me.
This is actually a little staged - I did use the spatula to hold the crack open more. I just couldn't get a picture off while holding both the brush and the tool.
But you get the idea.
You have 60-90 seconds to get the glue in and the repair clamped up before the glue begins to gel. Have to work quickly. I always do a dry run or two to make sure everything's read to go before I use glue.
I was able to get the crack mostly closed. It's a wide crack, it's been sitting for decades, and there isn't much movement overall. We do what we can.
Note the green arrow - I inadvertently took a chip of wood out with a spatula. Dagnabbit!
I suppose I could fill it with sawdust, but to be honest, compared with that old patch repair above it, it's not that bad looking. I can always go back and finish it.
So we now have a stable, repaired crack. Guess what? I found another crack on the top that needs to be repaired! Onward.