Marking Gauge

 

When you're making things out of wood (or out of anything really) you're going to be doing a lot of measuring and marking. This is a very simple tool, yet very useful for that sort of thing.

The bar is laminated from a couple of bits of oak, with a channel carved through for the steel rule to slide in. Any hard wood would do the trick; softwoods like pine would wear very quickly and get sloppy. The knob is 3d printed, and is glued to a bolt which screws through its nut, captive in a socket carved into the oak and epoxied in place, and the whole screws on to a presser plate that presses against the ruler to lock it in place.

The channel for the steel rule is square and tight, but not tight enough that the rule is guaranteed to be perfectly square to the bar; fortunately, for this tool, absolute squareness is not a necessity. If need be, one could reduce the play in the steel rule by increasing the width of the bar and channel, and still more by lining the edges of the channel with brass or something, but I doubt very much that I'll need to go to such lengths for the tolerances I work with.

The function of the tool is for making marks at a consistent distance from the edge of a piece of wood; I can slide it along an edge with a pencil held at the end of the ruler to make a continuous parallel mark. This is something that can be done with a combination square, of course, but this is lighter and handier, and the oak slides more easily than the metal frame of a combination square.