To make the pattern, I started with my favorite pattern material: MDF. I cut the pattern pieces on my table saw and then made the 45 degree angles with my router table. Since this is a split pattern, I had to make two identical halves.
A shot that shows the profile of the pattern.
The third try was a success. The first pour revealed a misaligned pattern, and a scrapped part. On the second pour, I didn't have the flask completely closed and the molten aluminum blew out the side and caused a nice 6 foot long darkened streak on my driveway. The third work beautifully after I added more alignment pins to the pattern and the flask.
The carriage cooling in the mold. This part was cast from an aluminum head that I melted down. You can see a hunk of the head in the background as well as the ingot mold that I use.
The carriage hot out of the mold showing the smooth surface finish.
After a bit of assembly and lots of hole tapping, here is the result.
Another shot of how the carriage is held captive by the two shafts.
Here you can see how one shaft is pushed against the carriage by the two allen set screws on the corners. This holds everything together and takes all of the play out of the system.
Two of the three ingots that I made with the left over aluminum from the head.