I like that taper attachment, very similar to the one on my Holbrook. Will you be fitting a screw adjuster for the "opposite" on the sine bar too? I think the.Monarch 10EE had a graduated micrometer collar on its taper attachment, might be worth a Google (and doing the geometry!)
I'm very rusty on casting, so take with a pinch of salt, but were I casting that I'd probably put the in gates where the ribs meet the vertical mounting plate (3 of 'em) and run a tapered runner parallel with the mounting plate, below the level of the casting so it filled from the bottom. I'd put risers at the top of each rib/plate junction and vents at the far ends, the far ends would probably cool fastest (most surface for mass of metal) so the ' corner' is where the worst shrinkage would be, thus where you need a nice fat riser or three to supply more metal.
I may be very wrong though, I often am...
I have the promise of a nice 200 litre! steel drum so I may soon have.the beginnings of a furnace and the prospect of some ally casting, I'd like to make a few replicas of fittings on the Holbrook (eg a toolbox bracket aping the one for the collet box) and perhaps a body for a headstock dividing attachment (to go outboard of the headstock).
I think I'll try lost foam casting first, as my woodwork's not as good as your, not nearly!:
Does anyone have links to a simple waste oil burner, one that doesn't need lots of high-pressure air or oil pressure?
Dave H. (the other one)