The wheel mortise gauge has two separate blades which are used independently to mark out mortises and tenons. The blades are bevelled on opposing sides so that they can always be on the waste side of the workpiece.
Fence of wheel mortise gauge
The fence has a non-marring face, meaning it will not damage the work surface. It has two thumb screws attached and the blades can be retracted into the fence to protect them when not in use.
Thumb screws of wheel mortise gauge
The wheel mortise gauge has two thumb screws, one on either side of the fence, to control both stems. When the thumb screw is turned, the corresponding stem can be moved through the fence to the desired measurement.
Stems of wheel mortise gauge
There are two stems each with their own blade on the end. Both are the same length and can be moved independently from each other so that the tool can mark separate lines.