Acoustic Guitar Construction

Three comments on laminated wood.

1. In conversation, Brian Burns told me he makes the sides of even his Flamenco gits thicker for players who wish to play for a large audience. Thicker sides result in string energy leaving through the top instead of the sides. Sides do not produce much sound, according to him. However, for those who play primarily in residential spaces for family and friends, he makes the sides as thin as possible. Thin sides result in a lighter feeling instrument and let the player feel the string energy as vibration against his or her body more, both of which which most amateurs prefer, he says. It is the pros who need the sound to project, no matter how that is achieved.

2. I am now just getting around to building with the laminated gypsy back and sides I purchased from Michael Collins some months ago. (Waiting for the gypsy mold to arrive from Ken's shop at the moment, then will begin at long last.) Indeed there still has been no spring back on the cutaway side. But the waist bend on the non-cutaway side has relaxed resulting in what looks like a "spring in". In reality it is spring back at the waist which results in pushing the lower bout (which did not spring back) "in". I will correct this with a bending iron once the mold arrives.

3. The back Michael ships comes flat, though the standard Maccafferi design calls for a strongly radiused back. I was able to induce a 15' radius into the flat back using a side bending blanket, radius dish, steel slats, and weight applied to the middle of the back @225 degrees F.

Michael uses relatively thick veneers, around .031". Each part is three plies thick. The outer is Indian Rosewood, the inner is hog, and I assume the middle is hog too. The glue is urea formaldehyde and penetrates (in places) through the wood to the surface. As he suggests in his videos, Michael uses plenty of it.

I found this pic of my first use of the bag. Not all those clamps were needed, but it was a learning curve. The sides turned out very nice. I use fewer clamps now, and could actually use fewer yet.

Couple things - for those sides I used an outside mold, with the layers temporarily joined in a row to give a large clamping surface. Put the lams in the bag, with the mesh going the length of the bag and between the vacuum inlet and the wood, press the bag into the mold, lightly clamp in a couple of spots, turn on the vacuum, finish clamping and done.

For the bubinga parlor guitar I've just started, I will be clamping to the outside of a mold, as Collins does - fewer clamps and easier overall.

This is interesting Dave. Harder to use an outside mold, perhaps. But it does save the trouble of building the inside mold when you are not too sure how many of that shape you want to make. Your outside appears to be quite thick.

Fella's a guitar Tech friend of mine asked me a question. To which my answer was I can't speak to that. The reason of course was I did not know the answer. I'm not about to BS a friend or anyone else for that matter. The question was" in laminating sides, does all the layers of laminates have the grain of the wood going in the same direction?" Sounds like a reasonable answer. In my reading I haven't come up with the answer. Can you help me?

Some luthers do 'double sides' which is two thin sides, same grain direction, glued together.

A true laminate has a "neutral axis" wood between, like an eastern maple or something of that sort.

Lonnie,

Typically, the grain is alternated in a 90 degree pattern. Some plies might be slab cut, others quartered, but the general grain orientation will alternate according to this pattern. Helps stabilize the final result.

On the other hand, there is no reason a 45 degree angle could not be used, especially if there are enough plies.

Dave is correct, as usual, when it comes to us oddball git makers. Ervin Somogyi does it that way, I believe. Michael Collins, on the other hand, does it in the typical fashion.