Drat, can't edit. Meant to say "if you're interested and want to discuss modifying moulds" in the email me bit.
Might as well go into it a little anyway. Alan's suggestion above won't work well (no offence Alan!). That technique IS used here and there, but it's tricky. I don't think it is worth using foam, especially with small or thin locating pins - too buoyant and easily dislodged, can result in off-centre castings or surface flaws. I've no idea whether it would cope with pressure-casting, also.
I think the best option is to completely divide the mould and make new half-moulds for the inner surfaces, but a good combination approach would be to create an RTV plug, to feed through from the rear hatch area and occupy the space that will become the cockpit. I mix the RTV with microballoons for these as it makes the stuff foamier, and hollow them out after they set, too. That way a spheroid plug larger than the opening it fits through can still be pulled safely from the casting. It needs to be rigid enough to hold shape, but also flex enough to get it out again - a foam ball won't do that. It's also a LOT more controllable. Note the hollowed area of the plug needs to connect to the casting chamber, or the pressure will squash it.
Happy to discuss further if you're interested.
Cheers,
Martyn
Might as well go into it a little anyway. Alan's suggestion above won't work well (no offence Alan!). That technique IS used here and there, but it's tricky. I don't think it is worth using foam, especially with small or thin locating pins - too buoyant and easily dislodged, can result in off-centre castings or surface flaws. I've no idea whether it would cope with pressure-casting, also.
I think the best option is to completely divide the mould and make new half-moulds for the inner surfaces, but a good combination approach would be to create an RTV plug, to feed through from the rear hatch area and occupy the space that will become the cockpit. I mix the RTV with microballoons for these as it makes the stuff foamier, and hollow them out after they set, too. That way a spheroid plug larger than the opening it fits through can still be pulled safely from the casting. It needs to be rigid enough to hold shape, but also flex enough to get it out again - a foam ball won't do that. It's also a LOT more controllable. Note the hollowed area of the plug needs to connect to the casting chamber, or the pressure will squash it.
Happy to discuss further if you're interested.
Cheers,
Martyn
