Monday, May 31, 2021

another casting video...

Casting an aluminum bronze calavera (sugar skull) for sale to the tourists. A calavera [plural: calaveras] is a representation of a human skull. The term is most often applied to edible or decorative skulls made (usually by hand) from either sugar (called Alfeñiques) or clay that are used in the Mexican celebration of the Day of the Dead (Spanish: Día de Muertos) and the Roman Catholic holiday All Souls' Day. Calavera can also refer to any artistic representations of skulls. This is a full video of the making of the mold. I've revised (and refined) my casting method since the previous video to speed up the process and render even better detail. I was getting too much shrinkage which was giving me a dimple on the back so I added a large feeder to the part. I'm using petrobond casting sand. The reddish sand is fresh petrobond that gets sifted over the pattern for good detail. The darker sand I use to pack the molding flask is refurbished petrobond that has been used several times. After casting, the really burnt sand gets put aside to be sifted, oiled (I use thread cutting oil), and mulled for reuse. I call the aluminum bronze alloy that I make "220"...which I mix by using 200 grams of copper and 20 grams of aluminum. That gives me a bronze that is 9% aluminum. I chose that mix because it is easy to use those numbers for different sized batches.


DEL said...

VERY Nice!!
I once rented space in a small foundry where they made propellers up to about 4 feet. I was building a hot rod but as I was there every day for 8 hours I got to learn a bit about casting and mold making. One thing I thought of as I watched your video was how they did the tamping. They used an air-operated chisel with a special head.
Just before I finished my project (you get a lot done if you put in 40 hrs a week without stopping to BS and drink beer) we did a 52 inch 5 blade prop. The molding process for that was indeed a big deal, as you can imagine there were undercuts. Very difficult and pouring was also critical. A lot of bronze and timing was everything.
Nuff said.

Milton said...

Outstanding John. Very precise and interesting process. Thanks

Brian said...

Wow,really cool process. The detail is very nice, thanks for the video

Hachita said...

Fantastic narrative & video (had to watch >1 at 0.5X). So much info. Still didn't absorb it all. Clearly an enhanced process. Like the recycled clay. The molten metal feeder/reservoir is interesting.

You seem ready to cast a 52 inch prop.