Popular Mechanics (South Africa)
HOW TO MAKE A MARKING GAUGE
A marking gauge is a crucial tool for any workshop. This is how to make one that uses a rotary wedge to lock it firmly into position.
CONTINUING OUR theme of building hand tools that use wedges to lock various settings into position, in this issue you’ll learn the process of building your own marking gauge. This tool uses the principle of rotary wedging to lock the beam tightly into the headstock.
This particular marking gauge is fun and easy to build, and uses very little wood. Search through your box of offcuts for some really nice wood that you’ve perhaps been saving for a special project, or pop on over to rarewoods.co.za and order several spectacular pieces of snakewood, zebrano, Macassar ebony or Masur birch.
WOOD FOR THE BUILD
For the making of this tool, we chose to showcase Macassar ebony and zebrano. Thanks to Brendan and Seamus HarcourtWood of Rare Woods South Africa (rarewoods.co.za), who sponsored these beautiful wood species for our project.
You can use almost any wood for your gauge’s beams and stocks, but we recommend hardwoods for both, as the action of the locking cam is powerful and softwoods will wear out quickly under repeated use. Macassar ebony and zebrano are really hard, and will stand up to many years of use.
An exquisite timber from Southeast Asia, it’s heavy and hard and historically used for woodworking tools, billiard cues, musical instruments, inlays, veneers and high-end cabinetry. It’s named after the Indonesian port of Makassar, which was a primary export location for this timber. Slow growing, Macassar ebony has dark and dramatic striping ranging from black to dark purple and brown in the heartwood. The sapwood is clearly demarcated and is pale gold in colour.
ZEBRANO (MICROBERLINIA BRAZZAVILLENSIS)
Also called zebrawood, this species is indigenous to West Africa. The zebrano tree can grow to around 40 metres with a trunk diameter of up to 1.5 metres. The heartwood is a light brown or cream colour and has dark blackish-brown streaks, which is where its name comes from.
All woodworkers use marking gauges. We use them for scribing out lines for chiselling joints or sawing, and for scribing lines to plane boards down to specific thicknesses. All you require for a gauge is two pieces of really nice wood – one for the headstock and one for the beam – and a small, sharpened steel pin or screw for scribing. Because this is such an easy-to-achieve project, why not build two marking gauges and give one to a woodworking friend?
Generally, marking gauges made today make use of a thumb screw to lock the beam into a specific position in the headstock of the tool. These modern locking mechanisms are made either from plastic or metal.
Our marking gauge is based on examples from a few centuries ago. It employs the geometry of a rotary wedge, more commonly known today as a cam. The simple action of rotating the eccentric beam slightly within the headstock will result in a firmly locked position for use, and rotating slightly in the opposite direction will unlock the beam.