Neck Heel Jig

Restoring a Vega C-40 arch top. We do not normally do arch tops. But this is a repeat customer, so here we are.

A previous repair tech ran a wood screw into the neck heel. As I am sure he/she discovered, this accomplished nothing. Fortunately, the heel was not split, which is usually the case.

This guitar has a simple straight sided V-shaped neck joint. A reset is required, so we are converting to a mortise and tenon joint. The goal is to epoxy a cherry spline or tenon into the neck heel and a matching slot or mortise into the guitar body. The spline is glued into the guitar body mortise with hide glue. This shows our neck heel machining jig.

A router guide installs on the router base

The neck is clamped to a board which is hinged at the top. I used rubber mat pieces to prevent slipping. The hinged board allows the neck to be adjusted so that the heel surface is parallel with the top of the jig, or angled as needed.

A slotted Plexiglas router guide is screwed down above the neck heel. At this point, the neck heel is adjusted level with the top surface of the jig.

This is the back of the jig. The black nob has a 1/4 x 20 threaded rod which runs through a T-nut on the other side. The threaded rod bears on the back of the hinged board. This forces the hinged board to any angle needed.

First I trimmed the lower heel preparing for the neck reset. On this guitar, the flat face of the heel butts right up against the neck block. Therefore the face of the heel must be trimmed to allow for a little set back. Next a slot for the cherry spline is milled. The spline is 3/8 inch thick, therefore the slot is 3/8 inch wide. The spline is epoxied into this slot.

The image below shows the trimmed neck heel with slot. Behind is the cherry spline wood which I will cut to fit the slot.