Marking Knives: Stuff They Never Teach You

Sometimes your woodworking improves like a slow and steady climb up a mountain. Sometimes, however, you get to ride the elevator.

When I first started woodworking, I used a carpenter’s pencil I sharpened with a knife. Then I traded up to a mechanical pencil, which never needed sharpening. Then one day I found my old X-Acto knife in my desk drawer. All through college I had worked as a production artist for a printing company, and I’d held onto my pica pole, a roll of 4-point adhesive tape and my beloved X-Acto.

This knife, I thought, might just be a mechanical pencil that never needed lead.

That day my woodworking skills took a much-needed lurch forward. Hand work, in particular, is much easier to manage with a knife line that never smudges, changes in thickness or is offset from the point you intended.

After a few years of woodworking with my X-Acto, I discovered spear-point, single bevel marking knives, such as the Blue Spruce knife shown in the photo above. Though some woodworkers would disagree, this form is ideal for marking joints for hand-cutting. The flat side rides the shape of the piece you want to mimic. The knife marks its location with zero offset.

But no one ever showed me how to use a marking knife. And sometimes it would follow the grain instead of the path I had set for it. Then one day, I realized what I was doing wrong. I was moving the knife too fast and with far too much pressure. Once I slowed down and took three light passes (in place of one heavy pass), my accuracy took another leap forward.

So slow down, and take it easy.

One final tip for those who have failing eyesight: Don’t throw away that mechanical pencil. If you need to add some makeup to a knife line, run that mechanical pencil down the knife line, then run an eraser over the pencil line. You’ll end up with a knife line filled with just enough lead to see it.

– Christopher Schwarz