After seven months of design, prototyping, trial and error, I have a hblb in my hands. This was the most difficult part that I have ever built, but it has paid off; the hblb is a success.
The aluminum begins to cool in the popcorn tin that I cast in. This was a very exciting moment because I really thought that this was going to be the one...I was right!
I love how the plaster shell looks against the rough aluminum. The plaster holds its shape well and stays on until you cool the part with water.
The plaster dip method is the best way to get your surface as smooth as possible.
A shot of the second hblb that I poured. You can see the edge of the aluminum can that I used as a sprue.
The plaster shell just falls off when you hit the part with a stream of water. The contracting aluminum fractures the shell and it turns to mud.
Wow, right after cooling, the part is shiny and quite smooth.
Side by side, the foamy and the hblb. I haven't done any measurements, but I'm guessing that the shrinkage of the aluminum will be 1-2%.
One area that needs improvement is the top of the mold where the bolt holes are. The aluminum cools before it can complely fill the cavity. A riser in this area should prevent this. I'm also thinking about putting a smaller pilot hole in the pattern. This would probably work as well.
After a bit of sandblasting and some sanding, the hblb is nearly ready. I haven't put in the adjustment bolts yet because I have to order them still. I'll also be using nylock nuts on the main bolts.
Nice shiny profile.
Bearings installed, ready to roll.