It's been quite a while since I updated this thread. I rescued one of the bad casting from the scrap pile. It took a bit of filling, sanding and some stratigicly placed "battle damage" but it came out pretty nice.
There seems to be some issues with the server and I can not upload the pics. Bummer I will try again tomorrow
You have a helluva project going there! Casting that thing as one solid piece is going to be problematic at best. Did you ever consider making several pieces? All the blades as several pieces and the center section as another. I think to get a good casting you may need to investigate pressure casting it.
I'm getting about 80-90 % complete castings and I have a few ideas to get them better. luckily all the bubbles are in flat easy to fix areas.
I've already got a bunch tied up in this mold to change things now but I think that a multi piece casting might be the best way to go if I were to do it again.
I did try slush casting one of these but it did not work out to well. There are some thin areas and with the time required to pour the resin in the mold and get things rotating the casting came out complete but was really thin in some areas.