This simple routing jig to be used on 4” diameter x 1 1/2” piece of wood to rout treads using a 8mm guide bush. The jig was designed in Sketchup. The top plate (pattern) can be changed as required as long as the “channel” is 8mm wide and is positioned on the jig using 4 locating dowels. The jig is small approximately 200mm x 140mm x 130mm and is designed to be used with a trimmer. There is a side viewing window to line up indexing marks as you spin the wheel around and a hole to either use a 19mm dowel (or your thumb/finger) to stabilise the wheel. Alternatively you can use a wedge between the base plate and the wheel.
SKP file can be made available on request.
-- There's two ways to do things... My way or the right way.. LBD