Neck Pocket Angle Jigs and techniques

Well, first, if you decide that you want to build in a neck angle, you have a choice of cutting the angle into the heel of the neck, or tilting the neck pocket. I've done both; there are pros and cons to each. For the set neck guitars that I used to make with Mike Lipe, and similar guitars that Keith Horne makes now, we cut the angle on the neck blank, early in the process, while it's still full width with no fingerboard. Clamped in one of my router planer fixtures, set to the angle with a cardboard gauge.

When I've needed to cut an angle into the neck pocket, there's been no special fixturing. A normal routing template with shims under the back end to tilt it at the small angle. You have to measure carefully and do the geometry to get the angle and the depth of the pocket where you want it. If you want to use that same angled neck pocket on multiple upcoming instruments, you make a routing template that has the tilt built in to it.

 

I shim the back edge of the jig a bit to angle the pocket. The jig in this photo was being clamped over a contoured body, so it fits relatively tightly to the top contour even though the pocket ends up being angled.

I like angling the pocket because it allows the end of the neck to remain square with the pocket when it is added. As far as knowing the precise angle that is going to produce the string geometry that you want there's nothing like drawing your instrument in CAD. I "group" the entire side neck profile and then you can simply adjust the tilt angle until you get exactly what you want and measure the resulting angle.

This is a copy/paste from the 30" scale semi-acoustic bass that I documented previously in this topic:

30” Scale Compact Semi-acoustic Fretless Bass Build

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79. The neck pocket routing guide jig is clamped in place and the neck pocket is routed. I do this in 1/16” depth increments until the correct depth (5/8”) is reached. The back edge of the routing guide was sanded to contour it so it could be clamped against the body to produce a uniform pocket depth.

 

Craftsman had and maybe still has a level that has a digital component that you can 0, say on the guitar top, then it will read out your angle off of that zero. Would help setting the angle of the template to the body.

Edit: I think this is the one: Sears.com

 

You can do it all with trigonometry, a calculator and a pencil. Calculate and measure how much higher one end is than the other. That's usually more accurate than trying to use a digital angle gauge, when working with small angles.

 

I do it Bruce's way. Use math to figure rise over run for the angle you want. Say, it turns out to be 1/16" every foot. That's easy to check for and doesn't need any special tool.

Put the template on a piece of scrap wood. Make a reference mark on the scrap so you can consistently place the template. Put a straightedge sitting on top of it, and measure the straightedge's height above the scrap a foot away from the edge of the pocket on the template. That's your "zero angle" height as a reference point. Tape a shim under the template, put it back on the scrap and check the height again, and adjust the shims until you get that 1/16" (or whatever) target rise above your zero angle measurement. So if your first measurement was 1/2", you're looking for 9/16". Once you get the shims right, fire up the router and make a cut on the scrap (doesn't have to be full depth, just skim the surface) and verify using the same method.

 

I'm not a fan of trying to measure an angle because (1) I'm too cheap to buy tools that won't see a lot of use, and (2) VERY small changes in neck angle will result in large changes in where the "ideal" string height at the bridge will end up. (That's why a relatively thin shim can make such a difference in action...)

I used a much simpler process. Since I knew the general height I wanted the strings to end up at, I simply fastened the pocket jig down to create the angle needed to create the pocket. What I had as constants were the thickness of the neck and the depth of the pocket that would give me the correct amount of neck above the body surface. I placed a straightedge on the neck pocket jig's top surface and measured the height of the gap at the bridge location, shimming the rear edge of my jig until the measurement would result in the correct angle.

It's harder to explain than to do, unfortunately. It's one of those things that ends up being clearer when you're in the process of doing it.

When I set up the angle I worked to create a neck pocket that would be very close to ideal, but at an angle that if it wasn't close enough I could add shims at the end of the pocket and not the body end. A few thousandths of shim at the end can be added and it won't create any visible gap where the neck meets the body. If you were to need the other end shimmed that would be visible. Hope that is sort of clear?

The process of creating a jig with the correct angle would be a whole lot easier on a flat-bodied bass, but in my case I needed something that I could "mate" to the carved top surface. That required a bit of one the fly improvisation.