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I glued the redwood top plates together yesterday. Things actually went pretty well. I was able to plane the edge and get a good surface without needing to pull out the sandpaper on the level.

I used hide glue for the first time on this joint. That went well too. I used the tape method to clamp. I also stuck it in a Cumpiano style clamping jig.

My problem is, that I didn’t end up with a completely flat surface on either side. My alignment was off a bit. Its flat for a while then about 3\4 way through it shifts to the other side. There isn't that much that would need to come off to flatten it, but I’m wondering about the best way to separate this. Since I used hide glue I’m thinking I could just heat it with an iron to separate it. Then re-plane the surface and redo. Or I could bandsaw down the line and give it another go. Is the heat idea realistic, or am I kidding myself there?

Thanks,

John

The only time I had that problem the plates were too close to final size and I needed to keep as much material as possible. I cut them apart with a little razor saw that has a 0.010" kerf.

Heat and a little moisture might work - I would use a damp cloth to separate the iron from the top.

Now I make sure I glue all of my tops together before thinning so I don't have to worry about minor misalignment.

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Steve Smith
"Music is what feelings sound like"

That's what I'd do.

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Just had this happen with a center joint that was discolored. I squared it up then used the table saw to re-cut the joint, trimmed off the discoloration then re-glued and following Steve's advice, made sure all this was done BEFORE thicknessing the plates.

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Thank You and Best To All

I haven’t thicknessed the plates yet so I still have room for sanding. It isn’t that bad, it just isn’t right.

It'll drive you nuts if you don't fix the alignment. Just use a small amount of water on a rag/paper towel to moisten the joint, and warm it up with a hair dryer or heat gun to separate the plates.

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Brad

If that's true, what diff does it make? It doesn't need to be perfect at this point. Accepting imperfection is a required trait in this craft, especially where it doesn't matter. IMO.

One of the reasons I thickness after gluing the plates is that I typically have an 0.010" to 0.020" mismatch between the plates. I just sand it out. If it gets much more than about 0.030" I would be looking at the method I use to join the plates.

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Steve Smith
"Music is what feelings sound like"

If its close enough that it will come out in the process of thicknessing, leave it alone. It you want to correct it you do have one option left before separating the joint. Apply a small amount of water along the line and let if soak in for a few minutes. Plug in an iron, turn it up to one of the highest settings but do not use steam. This will usually be sufficient to reactivate the glue. It will gel up normally after you remove the iron. Heat alone doesn't do the job with hide glue for long after assembly. I've seen it work with the right conditions a few hours after with veneering. A small amount of moisture wi give the proteins room to stretch out.

Another thing to consider is where the misalignment falls. If it will be in the soundhole cut out and under the fingerboard a slight misalignment is no big deal.

This is why I like LMI's Plate Joining Jig. Everything stays absolutely flat, so you can glue those thinner plates without issue.

FWIW, I wouldn't take the chance of being wrong about the thickness. I'd re-do the joint.

Thanks for all the responses.

Right after work I went out and worked on it. My gut told me to redo it, but of course I didn’t listen. Well...... my gut originally told me to just sand it, and then I thought "No the right thing to do would be to redo it." Then I posted my question and went with the easiest solution.

I went ahead and sanded it and it worked out. I’m at 0.130. I probably could have gotten it thicker, but the belt slipped on the drum sander and I had to fix that. I wanted to be slightly thicker for when I worked on the rosette, but I should still be safe here.

If it had gone wrong, I’d be hosed. In hindsight, if I had to do this again, I’d probably redo the joint. It would have been the save move.

Thanks again.