A simple homemade surface gauge.
The most complicated part is the block that clamps to the vertical shaft and holds the scriber. It's 1/2" x 1/2" x 3/4", bored 3/8" at one end, and 1/4" at the other end, the two bores being perpendicular. It is then slit, perpendicular through the 1/4" bore, down to the 3/8" bore. A 1/4" threaded shaft (a bolt) both holds the scriber and tightens the block on the shaft.
Drawing of the hard part
I've since replaced the nut with a nice knurled brass knob, and the drill bit with a scriber made from a broken drill bit ground to a nice sharp point.
© 2003 W. E. Johns