I thought this was clever

http://www.instructables.com/id/Spir...-Saw/?ALLSTEPS

COuld it be possible to make up a little jig to control the first cut by "pushing and turning" the workpiece with another piece of threaded material travelling through a nut clamped to the sawbench ? Might be worth some testing ? I dont know. Its on the list of things to try doing.

Bill