The Shopping list:
We mounted the motor in a steel box for protection against slurry splashes. The shaft should enter the tank at an angle off center to keep the slurry from osilating too much.
We mounted the percentage timer next to the motor with an outdoor switch cover over the controls.
We had success with minimal settling with a timer setting of 4 minutes on and 4 minutes off. The slurry got warm from the friction but not bad enough to cause evaporation. The only time it got hot was when we mixed new batchs of slurry for a 2hr continuous cycle. The shells ended up being very strong, had excellent detail and had minimal cracking thru dewaxing.
The slurry mix is also thinned dramatically so as to allow the shells to develop the pores needed for the shells to breathe.
More pores in the shell layers equals less necessary venting as with standard investment procedures.
The final dip is done without a sand coat so as to seal the shells
6-8 dips for large pieces
4-6 for small and medium size pieces.
Also, the weight of the metal to cast plays a role in determining shell thickness.
We really need to make a filtered cup grinder. Can you see it? I can. Humboldt State Sculpture had one, so shall I.
- shell repairs,
- another cup if one is lost,
- a tiny crucible,
- thrown into a crucible full of molten aluminum to stop the metal from oscillating in the furnace, etc.
The Shopping List:
- 90,000 BTU forced air gas burner
- 1 1/4 55 gal steel drums: (1 for the fire chamber and 1/4 for the water troff to catch the melted wax.)
- Angle iron for legs
- Steel sheets for baffles
- 4' steel bar
- Enough kaowool to line the barrel
- Ceramic buttons and bailing wire to tie back the wool.
A closeup photo of one of my shells after the final kiln firing. Can you see the crack that needs to be filled?
Something I will do next time to cut down on the shell cracking as a result of wax expansion in the burnout kiln. I will go full blast with the burner right away, no babying up in temp, straight to red. This flash melts the wax layer that is up against the shell before it has time to expand and cause a crack.