Jig for Greene & Greene S-spline

 

This is the Whiteside #1474 half-radius (or "fingernail") bit used with the spline jig.  Eagle America #161-0805 is equivalent.

It is installed in a table, together with a 3/4" O.D. guide bushing.  The bottom edge of the spline jig rides along the bushing.
Here's all the jig parts.  Clockwise from upper right:

1.) The top board of the jig, used to clamp the workpiece against the bottom piece.

2.)  The main body of the jig.  The workpiece fits into the notch at the top.   The notch is 0.015" shallower than the thickness of the workpieces. Four 5/16" aluminum alignment pins keep the top aligned; and a 5/16" elevator bolt is used for the clamp.

3.)  Drilling jig used to accurately drill two small holes in the workpiece.

4.)  The blue Rockler clamp and its barrel nut, and two washers used with it.  Two 3/32" brass rods are inserted through the jig top, through the holes in the workpiece, and into the jig bottom, to hold the piece securely in place.  Underneath these parts is the MDF template, which was temporarily attached to the bottom of the jig, and used to guide a pattern bit, which routed the edge along which the guide bushing rides against when routing the spline.
The jig all assembled, and ready to go.
The blank workpiece being tightened into the drilling jig.  The blank is 9/32" x 5/8" x 5.25".  I have a Whiteside 9/32" wide slot cutter, which makes the slot in the tabletop that the spline fits in to.
The jig is flipped over, and a #41 drill bit (which is slightly bigger than 3/32"), is used to drill the alignment holes.
Holes completed, the blank is ready to place in the routing jig.
Ready to begin routing the spline.
Bottom surface of jig.  The clamp's elevator bolt inset into jig.
Complete spline; test piece done in maple (lots cheaper than ebony!)