Box joint fixture, layout, and cutting technique for radial arm saw

by dorsey

Show more

Arts & Crafts

What's your vote?


The fixture was made of cherry-veneered MDF because I had a quantity on hand, and it's heavy enough to secure the workpieces. It mounts to the table in place of the normal fence.
Click to enlarge click to enlarge


The fixture was made of cherry-veneered MDF because I had a quantity on hand, and it's heavy enough to secure the workpieces. It mounts to the table in place of the normal fence.


Fitting the joints together. This demonstrates how the ends are cut so the fingers of one will line up with a cut in the other.
Click to enlarge click to enlarge


Fitting the joints together. This demonstrates how the ends are cut so the fingers of one will line up with a cut in the other.



http://www.makemania.com/widwimg/332/279/b_photo1_305x230.jpg
The fixture was made of cherry-veneered MDF because I had a quantity on hand, and it's heavy enough to secure the workpieces. It mounts to the table in place of the normal fence.
http://www.makemania.com/widwimg/332/279/b_DSC00020_305x230.jpg
A side view of the fixture.
http://www.makemania.com/widwimg/332/279/b_photo3_305x230.jpg
Aligning the saw blade with both the vertical edge of the fixture, and the fixture table.
http://www.makemania.com/widwimg/332/279/b_photo2_305x230.jpg
Marking the workpieces for depth of cut, which is the exact width of the boards.
http://www.makemania.com/widwimg/332/279/b_DSC00022_305x230.jpg
View of the fingers cut into one end. These are done and ready for the other end to be cut.
http://www.makemania.com/widwimg/332/279/b_photo5_305x230.jpg
A Jorgenson clamp is used to hold the workpieces securely to the vertical fence. This shows the cuts on both ends and it can be seen how they are made: the pieces are rotated end-for-end so that the fingers line up when assembled.
http://www.makemania.com/widwimg/332/279/a_photo6_305x230.jpg
Fitting the joints together. This demonstrates how the ends are cut so the fingers of one will line up with a cut in the other.
http://www.makemania.com/widwimg/332/279/a_DSC00024_305x230.jpg
Another view before the pieces are driven fully home.
http://www.makemania.com/widwimg/332/279/a_DSC00017_305x230.jpg
After planing the corners smooth. The glue swells the joints into a very tight fit.
Description

I made this simple jig to cut box joints on my Craftsman radial arm saw.  The fixture provides for holding the pieces securely and safely while cross-cutting with the saw blade rotated horizontally.

You'll need to know two things:  the thickness of your saw blade (the kerf), and the number of threads per inch in the saw head lifting mechanism.  The idea is is to lift the head 2x the kerf width for each cut.  For example, a 1/8" kerf means that the blade must be raised 1/4" each pass.  On my saw, that's four full turns of the crank.  You can count the threads or simply measure the rise per crank revolution.

Add a Comment