Hi Guys
Its a great surprise and honer that you've chosen the potty three cylinder for a team build, I wish you all a great success.
By way of background to the engine, its based on Edger T Westbury's Cygnet Royal Engine, you can still buy casting kits for his engine. I did a fair bit of redesign:- cylinders, crank, crankcase, con rods and a few more bits to make it look more interesting and easy-er to make from bar stock.
Room is tight in the crank case so you'll have to be careful to work on the plus side.
I also used cast iron for the cylinder liners and pistons you may change it to steel and aluminium without any effect on function.
I don't really know how team builds work, particularly with interfacing the parts together what with the mix of people with different levels of skill and equipment, so could I suggest that the screwed holes for fixing the parts together are left unmachined, so that that can be drilled through on final assembly that way you won't have a problem with holes lining up.
Ther's a complete build log on madmodder at
http://madmodder.net/index.php?topic=2317.0
I also had the build published in Model Engineer Vol 206 No 4397
I'll be sending PatH my drawings so he can do his convertion thing.
I will be more than happy to help with problems just give me a PM
Sound like a fun project
I hope you all enjoy it
Cheers
Stew