Gluing The Top To The Sides
Making an ukulele without any binding requires that the joint between the top and sides be very clean. There must be no gaps showing between the top and sides. Normally the sides are clamped into the holding form and the top edge is cleaned up by pushing the sides back and forth over a large sandpaper board. You can make a large sanding surface by buying 6" wide, or larger, sanding belts and contact cementing them down on a flat piece of plywood. Using cloth belt material is best. This sanding surface will last for a very long time. For radius tops, a sanding surface that has a radius is desirable, but for our slight radius a flat board will work fine.
Sides in a mold.
To sand the sides on the sanding board, clamp them so that just a half inch or so projects evenly from the mold.
Make a pencil mark all the way around the edge to be sanded so that you can see where wood needs to be removed.
Sanding the edge.
I relieve the edge of the tailblock so that the gluing surface is the same width as the top edge lining. This is not necessary, but I find it useful.
Tools useful for relieving the block. Sanding sticks made from self adhesive sandpaper and shop made sanding sticks.
The bracing on ukes without binding goes through the lining, but not through the sides. The sides need to be clamped closely top the mold shape so that the brace end and lining can me marked for fitting. Pay close attention to the centering of the soundhole. If the body shape is slightly off, the soundhole must be centered to the actual shape of the instrument.
Once the marking has been done, a small backsaw is useful for cutting the outside edges of the lining. Obviously you must be careful to not cut through the side.
A Dremel is a good tool to quickly remove the wood from mortise in the lining. All the wood from the lining mortise is removed as wide as the bracing and to a depth of about 1/8".
To help even out pressure on the perimeter of the top when doing the glue-up, a ring of hard cardboard can be made. If the top is radiused at all, the center of the top must be raised off the gluing jig.
Using a variety of clamps to do the actual glue-up of the top to the sides.
An alternative glue-up clamping method. You can use several pieces of wood across the body and run rubber bands under the jig. You could also tie the clamping board down. Whatever method you use, the joint must be as tight as you can make it.
