When I started to make guitars in my own very sparsely equipped shop, I made the jigs for each guitar as I needed them. One of the first things I needed was a way to join tops and backs. I had seen them joined with a system of bar clamps, but bar clamps were expensive, and in these days I was chronically broke.

I had some scrap plywood, and I conceived a way of joining that I still use to this day. I haven’t thought of any way to improve or refine it.

Home » By Sergei and Alan de Jonge » Lesson » Make a Joining Board

©2009 - Mark Kett

Fig. 1 shows the joining board. It’s basically a piece of plywood about 24” by 24” with two nubs glued on one side and with a slot cut in the other.

Fig. 2 shows the other pieces of the jig. A wedge and a “thing”. The “joining wedge” and the… … “joining wedge thing”.

Fig. 3 shows a top being joined. Here’s how it works: Once there is a perfect joint on the top (the subject of a future article), put the show side (bookmatch side) down on the joining board against the nubs with a strip of newspaper (or wax paper) underneath the joint. I use newspaper because it’s cheaper. Put the wedge against the edge of the top, then place the “thing” against the wedge.

Notice that the “thing” has the middle cut out, making only two contact points with the wedge. Clamp the middle of the “thing” just snug at first. Push on the wedge, allowing the “thing” to adjust, creating equal pressure at both points. Now the clamp can be made nice and tight. With the clamp tight you can put as much pressure as you want on the wedge.

Fig. 4 shows Alan driving it home with a splitting maul!

Actually, you don’t need a splitting mall for this. A few taps with a light hammer will do. I usually just push the wedge in tight by hand. That’s enough pressure, if the joint is good. Like I tell my students: “If you have a good joint, you don’t need much pressure; if you have a bad joint, pressure won’t make it good.”

The weights are placed on the top as close to the joint as possible to keep the bottom surface (your good side) even, and also to keep the top from buckling up. This will happen if you apply a lot of pressure with the wedge.

Fig. 5 shows the versatility of this system. Here, a top is being joined that has already been cut to shape. No problem; the jig still accommodates it just fine. Of course this jig works just fine for gluing backs as well.  §