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Using the Shopsmith Mortising Attachment to drill square holes
As you probably know, a mortise is one-half of one of the most classic of all wood joints - The Mortise-And-Tenon. This is the joint where a square ?peg? slips into a square hole, providing strength and beauty, resisting pressure from almost any direction, while giving your project that ?classic? look of beauty that's tough to beat.
Cabinetmakers most often use the mortise-and-tenon joint when they join wide crossmembers to uprights, such as table aprons-to-legs or wide spreaders to cabinet carcases. Carpenters, too, make use of this very strong joint in post-and-beam construction. Classic American barns are an example of this construction technique.
The mortise-and-tenon joint gets its strength from opening up large gluing surfaces where the long grain of one piece of wood is joined to the long grain on a mating piece.
The Mortising Attachment used to cut the square holes is a two-piece accessory that holds the square Chisel in place while an Auger-Type bit spins inside, removing the wood as the Chisel is advanced into the workpiece. The Hold-Down that's included in the Package attaches to your MARK V Rip Fence to hold your workpiece down against the Worktable surface when the Chisel is withdrawn from the stock.
Let's take a look at the step-by-step procedures for using this handy Accessory.
The Mortising Chisel MUST BE SHARP before attempting to use it. New Chisels come pre-sharpened and ready to go. If you have purchased a used Chisel set, be sure to use the appropriate cone-shaped Shopsmith Mortising Chisel Honing Stone to sharpen it prior to use. There are three different stones available:
A 50-degree Stone that will sharpen all three of the Chisels in the current Mortising Package.
A 41-degree Stone that will sharpen the 1/4" and 3/8" Chisels that were originally sold prior to 2000.
A 46.5-degree Stone that will sharpen 1/2" Chisels originally sold prior to 2000.
Make a simple jig like the one shown here to support the Chisel during the sharpening process. The top of the Chisel can rest against the face of your Rip Fence for backup support during this sharpening operation.
Grind a mortising chisel as shown. Retract the quill and repeat until the stone stops removing metal.