If you enjoy making your own woodworking tools, as I do, here’s a good-quality marking knife you can create from a humble used-up spade bit and a small scrap of wood.
To make the knife, begin by grinding a 3⁄4″ spade bit to a V-shaped tip as shown, then grind the bevels on one face of the bit. When grinding, quench the metal occasionally in water or oil to prevent bluing it and drawing the temper. Then hone the bevels and opposite face of the bit to a mirror polish on sharpening stones. Then use a hacksaw to cut the round shank about 2″ long.
To make the handle, first cut a piece of stock to about 5⁄8″ x 1″ x 5″. (Here’s a chance to use some of that exotic scrap you’ve been hoarding.) Drill a 2″-deep hole into one end, then shape the handle for a smooth, comfortable feel. Epoxy the shank into the handle and you’re done – you’ve got a beautiful, functional marking knife that probably will outlive you.
– Peter Giolitto