Years ago I started to make a routerlathe, but life got in the way and it never happened,
I took all the pulleys and cables off an old draughtsman's drawing table, those massive ones about 4 ft across with tilting table,
Not sure if I've still got all the pulleys somewhere or whether they got junked in the move!
If you can find one, possibly from an ex WD or machinery dealer etc, they have 3 alloy pulleys plus a larger one with a helical cut groove, the cable was under spring tension and the arrangement allowed the square to be pushed up and down the table and retain parallel travel,
It wouldn't be too difficult a task to use screw or fusee cutting methods to cut different grooves on something either to replace or slip over the original pulley to suit different helix pitches, and cable can be bought off the roll in various places!
You'd need to then rig up steel rods, a mounting for the router to be used, centres for the stock and a handle to wind it along!
John
Edited By RJW on 03/02/2013 09:45:53