A marking gauge is a tool for scribing a line parallel to an edge of the workpiece. It consists of a stock (a block with a hole) through which a stem runs, with a sharp pin or cutter at the end. Lock the stock at the required distance, run it along the edge, and you scribe a perfectly parallel line. In Dutch the tool is called a kruishout.
Why scribe rather than pencil
A pencil line is at least half a millimetre wide and moves with the point of your pencil. A scribed line sits exactly on the measurement, and has a second advantage: the scribed groove is a channel your chisel drops into by itself. On mortise-and-tenon joints and rebates, that is the difference between tight work and sloppy work.
Variants
- Single marking gauge — one pin, one line: rebates, widths, thickness marking.
- Mortise gauge — two pins on the stem, adjustable separately. You scribe both lines of a tenon or mortise in one pass. Set the pins to the width of your chisel and the mortise matches automatically.
- Cutting gauge — with a small blade instead of a pin. Essential across the grain and on end grain, where a pin follows the grain and wanders off.
Working accurately
- Choose a face edge. Always work from the same reference edge. Swap sides and your errors accumulate.
- Set the gauge off the work itself. Where you can, set the pin against the part that has to fit — your chisel, or the thickness of the mating timber — rather than reading off a rule.
- Press the stock firmly. Keep the stock pressed against the edge throughout; let it drift and the line drifts with it.
- Light passes, several of them. Scribe lightly first, then deeper. One heavy pass and the pin dives into the grain.
- Drag, don’t dig. Tilt the tool slightly so the pin trails rather than chops.
A second meaning
In Dutch, kruishout also refers to a cross-shaped assembly of two battens fixed at right angles — for instance a cross in a church, the base under a Christmas tree, or the control cross of a marionette.
Related terms
- Mortise and tenon joint
- Timber joints
- Rebate
- Square
- Chisel
- Spirit level
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