How to Use a Toolmaker's Surface Gauge

Clean your working surface. The surface must be flat and free of debris. Toolmakers and machinists will typically use a surface plate to work on for precise measuring but any smooth, flat surface will do.

Set your work piece (the piece you will be scribing) on the work surface. Leave room to work around the piece so that you can manipulate the surface gauge. Set the surface gauge on the work surface and ensure you can slide it along the work surface smoothly.

Secure your scriber attachment to the surface gauge. The scriber will slide through a holder that mounts over the upright of the surface gauge (called the spindle). Tighten it into position with a thumbscrew that also tightens the holder in place on the surface gauge spindle.

Set the tip of the scriber to a particular height to scribe a line at that height. Use a known reference point of the work piece, or use gauge blocks stacked to the height required. Set the scriber point by loosening the thumbscrew on the holder enough that you can move it down the surface gauge upright. Move the holder so that the scriber tip is slightly above the desired height and tighten the thumbscrew to lock it in place.

Loosen the spindle clamp near the base of the surface gauge. This allows the spindle to tilt backward or forward. Tilt the spindle forward to rest the tip of the scriber on the gauge blocks, or at the reference point height, and tighten the spindle clamp.

Keep light but firm pressure on the base of the surface gauge so that it does not wobble or tip. Move it along the work piece so that the scriber tip touches the work piece lightly, but hard enough to scribe a visual line.