Why do we do this?
To smooth the transition from the peghead face to the edge of the fingerboard.
Do all headstocks require scalloping?
No. Fender style headstocks require scalloping due to the curve of the peghead face. Pitched bevel headstocks do not require scalloping due to the fact the face is flat.
What is the proper measurement for scalloping?
Generally speaking, the idea is to lower the peghead height a little less than or up to 1/4 inch for a Fender-style 4-string build. However, the amount of height you take away is based on your design and your personal preference.
Use a spindle sander with a fence borrowed from the router table clamped on. As with most woodworking procedures it is important not to take away too much wood on the first cut. Do it in incremental steps. Bear in mind while you can always take away wood, it is impossible to put it back.
Is the radius curve absolute for all scalloping jobs?
No. The specific radius of the curve is not necessarily absolute because it depends on where your first tuner is (as in the first tuner met after the nut, which would ordinarily be string 4 or “low E”,) and the total amount of material being removed from the peghead face. A 1″ radius, which is created with a 2″ diameter spindle, will probably work for most builds. In our photos it is a 3″ drum is creating a 1.5″ radius. The idea is to have the peghead flat before the first tuner is reached so the tuner’s bushing has a flat surface to be tighten down on.
(Note: The neck shown is for a 6-string guitar, but the same method applies to Fender-style bass guitar necks.)
Where are the rest of the build steps?
You can view them all here.
At what point should the scalloping be done? In your picture it looks like the fretoboard is on and you have already cut the shape of the neck. I thought it would be easier to scallop before cutting the neck down since the edge is still at 90 degrees from the headstock it would be easier to stand the neck up on it’s side. This is my first bolt-on build, never scalloped before.