toy robot project
by bryanbrutherford, published
I wanted to upload this project to show the various processes that can be paired with 3-d printing technologies to create a DIY factory for higher volume home manufacturing. Ultimately the final part isn't very complex but i have used similar processes for other more technical projects.
A friend asked me to make small plastic toys of his company logo to use as promotional items. I ran through the possible processes to do it, the volume needed was too high to use just a 3-d printing solution and too small to justify the cost of traditional manufacturing.
I started by creating a 3-d file of the logo in solidworks and then printed some parts for size and scaling reference.
Once we had the scale decided i used a high res 3-d printer to print a test mold which was a simple negative cavity made from the original 3-d file. I used this just to prove the process and make sure the geometry of the part wouldn't cause any casting problems and to check that the final cast part would be durable enough.
Then i used a small desktop roland mdx-20 mill to cut a wax positive to cast a mold from. the file for this was just an assembly of multiple original parts laid out on a uniform ground plane. When the cut job was finished i moved the positive over to a small manual mill to clean up some edges. I added some plexi to the sides to box in the part for casting. I ended up pulling multiple molds from that original positive so i could cast dozens of parts at once.
I used smooth-on oomoo silicone to make the molds since the part was so simple and this particular silicone is incredibly easy to use. the final parts were cast with smooth-on smooth cast and compatible pigments.
The molds were simple one sided slop molds i measured out the amount of resin i would need to fill all the molds and then added about 1/4 cup extra.
I added extra so any bubbles in the mixture would rise out of the mold in to the overflow above the top edge of the casting. I then ran a squeegee over the top of the overflowing molds and forced all the excess in to channels that i designed in to the mold. You could just push the excess over the edge of the mold but i like to make a slight attempt to keep my work area clean.
the resin set up in a few minutes and the parts pop out like an ice-cube tray.