Introduction: Small Figure Casting Via the "Bologna Sandwich Casting Method"
I heard about Bologna Sandwich Casting at TechShop Detriot so I decided to give it a shot. The objective is to make small customized figures to be used in games such as Monopoly; and I made it at TechShop.
To make the figures I used:
Painted hardboard from the TechShop scrap bin
Thin card board from the Techshop scrap bin
Pewter (from Armstrong Tool Supply, http://www.armstrongtoolsupply.com/)
Jax Pewter Black (Armstrong Tool Supply)
Inkscape (vector drawing program)
Nib pen (alternately one could use a small paint brush which I couldn't find at the time)
Dremel (with small bits and grinding wheels to remove flash and web)
Large document clip (or c-clamps)
Heat source to melt pewter
1. First I found an image to make into a casting and edited it in Inkscape.
2. Since this object has a front and back that are sym-op I needed to reflect the art so I'd have both faces. (see image 2) The two halves need to be aligned also so I created some reference lines (in red) that are on a different layer that would be used to cut the two pieces out of the stock. You will also notice that I added a thick black line to be the base as well as a sprue. The real work was figuring out to what depth (and therefore what shade of grey) I wanted each element to be in the casting.
3. Next I etched the image into the hardboard and cut them out using the Epilog laser. As you can see in image 3 the laser did a good job of etching each color to a different depth in this test on a piece of mat board.
3. I decided the base wasn't going to be wide enough so I glued another small piece of hardboard to each half and used the Dremel grinder to create a deeper pocket. (image 4)
4. Then I clamped all the pieces together using a large document clip. Then I removed the handles on the clip so it would stand up.
5. I set the mold on an old electric skillet to protect the workbench. Then I heated the metal and pored it into the mold. The first couple attempts were just "okay" so I decided to make it easier to get the mold to fill by thickening the entire piece. I did this by making a spacer (a thin piece of cardboard that I cut out larger than the profile in selected areas (see image 6 showing the raw casting). You can see this spacer in the image of the assembled mold. I also put some small air passages in it to make it easier for the metal to flow.
Note: I found out that it's better to pour a lot more metal than is needed to fill the mold - at least when the sprue is as short as mine was. The additional pressure of the liquid metal helps fill the small voids better.
6. After it cooled I removed it from the mold, then using the Dremel and files I removed the flash, the web between the lower bones at the base and brightend all the raised parts and edge details.
7. Although it looked good at this point I decided I wanted it to pop, so I used the Jax Pewter Black in the face recesses. (see image 7) I used a nib pen to puddle the fluid and let it set for about 10 min. Then I used a paper towel to dab up the fluid and repeated the process on the other side.
I am very happy with the way this project is working out. I am amazed at the detail that the laser can create and that it translated so well into the casting. I have 3 more unique figured to cast.
The final image shows all of the pieces I made.