Wood-Marking Knife

A woodmarking knife made from old sawblade steel and leftover wooden handle.

Small gift for a friend of mine. He gave me this wooden handle for a different project years ago and it went unused, when he got back into woodworking he mentioned wanting a marking knife. For those unfamiliar, these knives are used to follow straight edges for marking where to cut or chisel on a wooden workpiece.

With no toolsteel I opted for an old metal sawblade, its hardenable and thick enough for the job. Below are the steps, some notes, and select pictures from the process.

Steps:

Sharpie rough shape onto blade and cut out with angle grinder.
Normalize the steel for easier working. (Heat red hot and let air cool to soften the steel)
File profile, blades edges, and tang
Quench harden in water (Heat red hot and drop into water)
Sand blade bevels and edges flat.
Temper to straw yellow (Heat gently until oxide on blade turns light yellow)
Sand body and sharpen final edge
Epoxy the tang into the well lacquered wooden handle
Final polish
3D print a safety cap with rubber inlay so the cap stays in place

Note: I opted to harden the steel and then flatten out the blade because I was worried about warping the steel during hardening. Might have been overly cautious, but I was working with unknown steel and a basic flame/water quench.

Using an angle grinder to cut rough blank from the hard "stock." Exact shape doesn't matter as we can refine it later with files.

Normalized (heat softened) steel is much easier to cut to shape with a file. Coating the blade in black sharpie makes it easy to scribe (scratch) in layout lines to guide cutting.

This is all you need for a simple hardening. Heat the steel until its red hot (specifically until no longer magnetic) and drop it into water.

Granite blocks make for firm and flat backing for sandpaper.

I sharpened the blade before attaching it to the handle, blue tape was used as a temporary safety cover. Note the roughened tang of the blade to give the epoxy more surface area to grip.

Wood PLA filament makes for a nice blade cover. I glued a small piece of rubber inside the print to help keep the cap in place. Note: Bicycle inner tube (used) makes for a good source of small rubber sheets.