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Old 02-15-2017, 07:42 PM
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Bruce Sexauer Bruce Sexauer is offline
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Join Date: Jan 2009
Location: Petaluma, CA, USA
Posts: 6,673

Originally Posted by tjp View Post
Bruce, how do you build the top arch in? I am guessing cut a 1.5ish degree angle into the blocks so they are vertical in the workboard (which I assume is arched). But then there are the sides, you don't have the luxury of using a dish on those before gluing the top.
It is probably simpler than you think. The workboard IS the dish. The sides only need contact the dish at three points, the ends (where they glue to the blocks) and the waist, the deepest part of the workboard/dish being used. I calculate this depth (put a straight-edge across the dish and measure the gap where the waist will be and subtract a hair) and then set the jointer up to make that depth of cut from both ends, making sure to stop a couple of inches before the waist point. There is no reason for the sides to actually fit the top as the peone make the connection, and the "gap" gets cut away in the binding ledge routing anyway. I use a very shallow dish, so on a wider guitar like this the jointer cut is only 3/64" or so. The goal is for the side to be plumb: perpendicular to the plane of the top, as if there were such a thing.

I actually make the peone 1.25 degrees over square, but your guess is very close.

Here is a picture, but you'll have to look carefully to see the relief cut into the sides either side (the waist is the center, so above and below as pictured) of the waist: