Glue, Clamping And Squeeze Out (7th Ave. ?)

[wardd]

Folks,

I'd like some other opinions on glueing.

I've always been a believer in using good even pressure on the entire surface being glued, as opposed to using clamps that are spaced out.

For example: I made the jig shown in the links for making laminated neck blanks.

It uses a 6 in. wide steel u-channel as one side and R. Goldberg 2x4 and bolt clamps on the other.

With it I can set clamps with no space between along the entire length of the blank.

I guess I just don't feel comfortable when some of the surface has no direct pressure beyond the tensile strength of the wood.

It seems that glue from a clamped area will push into the adjoining unclamped areas and not squeeze out as good as it should.

Thus, leaving stronger and weaker areas as well as thicker and thinner gluelines.

What do you think, is this overkill.

Squeeze out is my other question:

I use sponge blocks to apply glue. i.e. I apply the glue to the surface then use the sponge block to dob it so I get a nice even layer of glue. I do this with both surfaces to be glued.

With this method I get minimal squeeze out, as opposed to the glue running everywhere thing I have seen in pictorial photos.

Again, does this seem like a valid approach.

Be Cool,

d ward

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[bassman]

The only real difference I see with your jig and the moretraditional approach of glueing is that you are applying more pressure to the edges of your laminates. The wooden blocks you are placing across the laminates are bound to flex a little since the "clamps" or bolts are tightened in unsupported areas. This is however splitting hairs, hairs that may not matter, I really dont see any advantage to your method of clamping, over the alternative of just laying a board across the top, and one across the bottom and the using them as clamping cauls. If I was worried about getting equal pressure across ,my glueups, and I am, then using harder wood than the pine you use is the way to go. I use either very thick and quality plywood or oak/maple. It will flex less and act more as an extension of the clamps than a softer piece of wood that will more likely put more pressure directly under the clamps than in the spaces between them.

[Mattia]

Sure, works fine. Re: clamps, well, that's what cauls are for. If the piece is wide enough, the wood itself will spread the pressure just fine. I like to put as many clamps as is workable, and give it a good amount of pressure (I've never managed to starve a titebond joint, BTW, and I've only heard very few people claim they had). For fingerboards, I use a caul, and space cam clamps every inch or 2. Fewer clamps for doing solidbody blanks, usually, if they line up well. Your setup looks like it'd work well, although it might be a bit slow tightening things up and getting even pressure across the board.

Re: thicker/thinner glue lines: never seen that happen if I jointed the pieces properly, and used appropriate numbers of clamps. Glue has quasi no strength of its own. Wood has a lot. If you're gluing up two pieces, you're doing that after you've got them mating quite tightly in a 'dry' run. In terms of squeezout, I like just a small bead squeezing out all along the edge of the joint, just enough. I use the best glue spreaders on earch, aka 'fingers', most of the time, and have learned to use less glue than I used to think was necessary. You want some squeezeout everywhere, just a tiny bit, to show you that the glue's coated all the surfaces.

[wardd]

Bassman,

Thanks for getting back to me.

I do use a piece of 3/4 plywood as a shim between the 2x4's and the neck block that I didn't bother to show in the picture.

I was thinking the same thing and have checked the flex in the blocks with a straight edge before and after adding pressure.

With only a 6 in. spread between the bolts they hardly flex at all and the shim should even out the pressure.

I appreciate your input.

Be Cool,

d ward

[wardd]

Mattia,

Thanks for getting back to me, you must have been posting as I was replying to Bassman.

Glad you agree with me on the squeezeout issue, makes me fell better about it.

I've been using polyurethanes for neck glueing so the finger spreader approach is not so pleasant as with the alaphatic resin glues.

Then again, I wear rubber gloves when working with the poly glues so that would work too.

By the way, I'm a high school teacher and I have one student who is always talking about moving to Amsterdam. I've got to remember to tell her that when she gets there not to stand in the window.

Thanks for your input.

Be Cool,

d ward

[erikbojerik]

Looks fine to me too.

I actually lay my blanks down flat (fretboard side up) with a 60" long aluminum 1" angle on either side, they are dead straight and don't flex at all. With this arrangement a clamp every 3-4 inches works fine, I've never seen an open seam due to anything but planer tear-out in one of the lams.