Thanks guys and gal, the interest is much appreciated.
Jeff - your crankcase looks great. Hope you pick it up again before too long.
Roger - glad to hear you're planning to build one too. Let me know when you get going. What I've learnt so far is you've got yourself into a large amount of work
Jo - yes you need to build one
Vince, Dave, Carl, DavidF, Don & Camm - thanks for climbing aboard.
So I decided to have a crack at making the fins today. That's the bit of the cylinders that had me most worried. To do that I had to make up the super narrow groving tool and an arbour. I've recently taken to making screw cutting tools with the right size flat on the end for a given pitch. So I made one of them for the 5/8 x 18TPI UNF nut I got to put on the arbour. BTW I'm not following the instructions from Lee very closely.
Here's an early test of the grooving tool on the dud cylinder blank
Here's making the arbour
Then I used an indicator
and a list of stop positions
then tried out the whole procedure. I ended up stuffing up another cylinder blank, so I'm one in arrears now. After much stuffing about I eventually got the grooving tool cutting very freely. I'm running the cylinders at about 650 rpm for the grooving now, which is fast given the 1-3/8" OD. The higher speed also helps with clearing the chips. Makes alot of mess with cutting oil though
Finally I broke the sharp edges with my trusty old chamfering tool
Here's the semi-finished product. The good one is at the front, the one that was already stuffed is on the left. Todays reject is on the right.
I've got the procedure working good now and think I'll be able to make good progress with the grooving from here. I'm now getting first hand knowledge of just how big a job this project is and it's sure alot bigger than what I've tackled in the past, but that's ok.
One last note for today - if anyone reads this who is trying to do the fins for them self and having alot of trouble. You could always make an arbour to go on the rotary table and cut the grooves with a slitting saw on the mill. Getting the grooving to work well on the lathe isn't easy.
Steve