As most of you are aware I'm more at home with a Lathe than an Oscilloscope !
I read about the Clem motor many years ago and often wondered how the conical portion could be reproduced. well, I have a plan.......
My intermediate Lathe is a Harrison L5 which came with a very useful extra, a taper turning attachment. This allows me to machine a piece of material to a conical shape. It dawned on me that once the taper was created using fine feed I could then go into screwcutting mode and put the spiral groove, possibly 8 of them ( using dial index method ) because the cutting tool would still be influenced by the TT attachment.
Having had a wealth of experience with scale IC engines, the smaller they are the more difficult they become to get going I am wondering what size I should make the cone ?
Chet suggested I launch this thread so OUR members could add any further, possibly missing info to this subject.
Nanny state ? Left at the gate !!