Thanks Rudi for making this instructable. My version of this jig uses plywood gears of various sizes and ratios to change the pitch. Pretty cool to use the stepper motors to do this. I wrote an Excel file that lets you design the helix graphically using sliders - then it gives the values for all the parameters to setup the jig including bevel angle, centerline offset, pitch, and radius of dowel. It can also make the helices right or left-handed.