I've got one. I can measure it later when I get down to the shop.

Just curious, but how long does it take to match up the halves, wrap the rope, and insert the wedges, after the glue has been spread on the edges?

This style of jig with wedges and ropes has been around for hundreds of years and is called a Spanish tourniquet. They work very well but they are no substitute for not learning to properly join a top and hand plane technique including sharpening technique.

This is not directed at you Mike it's simply on my mind. In the past some search for a better method to join plates because they had poor results in the past. No matter what joining methods one uses it will never correct poor joining technique in the preparation of the joint.

With that said... I built a Spanish tourniquet and used it on the first maybe ten guitars. Then I learned the tape method and that I did not have to store the jig any more and I never looked back. With good joining technique the tape method was all I needed for the next and production guitars I built.

I used the tape method to join head plates, heel caps and rosette blanks and it worked great. No jig required just some tape, wax paper and something to weight things down.

I've tried a few different methods and all seem to work well. One thing to watch for is how the grain looks. i have a bunch of tops with very fine grain that made it almost impossible to find the center once joined. I have to offset the two panels by a few millimeters to save me some frustration.