Rare Saws




  The Eleven Grooved Box – Tools Update by Jim Harvey 1 of 3  


I have an improved fixture for making Eleven Grooved Box splines.



This article relates to my original post: Eleven Grooved Box Step by Step – Part 1 and 2 by Jim Harvey

Roy Underhill’s video shows the spline blank placed in a grooved block. Then the blank is planed to size with a block plane.


The problem is, this eventually cuts some off the top surface of the grooved block causing the splines to come out too small. Then the splines won’t do their job well and look terrible.

My improved method has three secret weapons:

1. A Kerfing Plane to make the blanks

2. A modified Dado plane with skewed blade

3. A sizing block with a channel to guide the modified plane

Secret Weapon #1

Tom Fidgen, in his book “Unplugged Woodshop” describes a kerfing plane. You can get parts to build one from Bad Axe Tool Works. Tom's kerfing plane looks a lot like a stair saw with a fence, you can see it on his web site.

My version is made from a vintage plow plane and a blade cut from an old rip saw. It’s easy to cut a tempered saw blade. Just score it on both sides with a Dremel grinder and cutoff wheel. Put the blade in a vise and flex it, it will break along the score line.

The next problem is drilling holes in the hardened blade. It will wreck a conventional twist bit, but I had good luck with carbide tipped masonry bits. First, center punch the hole positions well, drill a pilot hole with a 1/8″ masonry bit, then finish with another masonry bit sized to fit your screws. Use plenty of oil while drilling.

Kerfing Plane

This old plow plane has an inch or so of the adjusting threads stripped so I added a spacer block to the fence to skip over the bad spot. The next photo shows the kerfing plane making 5/16 inch deep slots in the end grain of a Walnut scrap. The modified plane is accurate enough that I can easily slice four spline blanks from this 7/8″ thick bit of wood.

Kerfing plane in use.

Now that three kerfs are cut, use a backsaw to cut the four spline blanks free. I kerfed both ends of the Walnut scrap while I was at it.

Cutting the spline blanks free.

The end result after a bit of block planing to remove saw fuzz. Eight spline blanks ready to be trimmed to size.

Batch of eight Walnut splines.

Woodworker's Guide to Wood Collection only $79.99 at Shop Woodworking
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W. & S. Butcher


English Chisel


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