Dan,

The "chuck" you ask about is the fixture you see being built in the second installment. It is designed to hold the case in axis of crank CL and cylinder CL in the lathe. Boring on a lather is much much easier then on a mill, so I make every effort to do as much on the lathe possible saving the mill setups for screw holes and port work.

The forth shot is the gearbox of the lathe. It is not a "quick change" box so you have to set up the gear ratios to cut the screw pitch you want. in this case 32 TPI LH which is where the main bearing housing will thread into the case. The gear at the top on the spindle drives the train, the one at the end on the bottom drives the lead screw that actually drives the saddle of the lathe.

The caster is going to replace the casting. I have JB welded it and recut the faces but thats not really the way to do it. I'll use this case to fit everything and when the new case comes I'll machine it up fresh. Maybe I can get some good shots of the thread cutting process then.