Small Figure Casting via the "Bologna Sandwich Casting Method"

Picture of Small Figure Casting via the
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
Cyanoacrylate glue
Pewter (from Armstrong Tool Supply,
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)
Jewelers files
Exacto knife
Epilog Laser
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.
lime3D2 years ago
I'm a member at Techshop Detroit too. I've seen people doing this, but haven't tried it myself yet. Question... are the molds one-time use only? Meaning, if I want to cast multiple pieces, do I need multiple molds?
in0v8 (author)  lime3D2 years ago
If you have some draft in the molds they will come out cleaner and not be damaged as much when removing the castings. You might also try using some graphite or other mold release for the same reason. That being said, I was usually able to get three attempts from each mold before they started coming apart. Since I knew I would not get acceptable results every time I poured I etched several copies of each mold. The Kitty only took 3 tries and was the first one I did. The dino on a bicycle took and vitruvian man each took 5 attempts, the Iowa took about 7 - mostly because the lettering was not coming through.
RangerJ2 years ago
Interesting but I'm a little fuzzy on the part dealing with the mold. How do you make/use the mold?
in0v8 (author)  RangerJ2 years ago
I used the laser to etch the designs into each half of the mold. The darker the filled area the deeper the laser cut.  I also used the laser to cut out another thin piece that was a silhouette of both faces of the the design. This piece acts as a spacer so that the cavity created was wide enough to fill with metal. I've added a picture that I hope helps.
poofrabbit2 years ago
Boy do I wish I had a techshop near me! This is fun, I could see all sorts of fun things made using this method, nicely done.