Step 7: Casting: Body and Arms and Legs
I decided to use Smooth-Cast 300 to cast all the pieces. My original plan was to use this ultra white plastic as the final surface of the turret, with only some clear coat added for extra shine. After some test casts I determined that wasn't really going to work for a few reasons. More on that later. With weight being such an important issue, all pieces relating to the body will be hollow, and all leg pieces solid for extra strength and support. I'll talk about the body and arm first.
My goal with the hollow pieces was to create a shell that is roughly 1/8" thick. After doing a few tests with different ways to achieve this, I decided to slush cast each part of the mold separately and then merge the 2 halves to create a final cast. This helped to guarantee that there weren't any spots that were too thin.
By doing it this way I can add a little extra plastic wherever it might be needed. I built up the thickness in layer for each half of the mold. I made sure to not let the plastic fully cure between each coat so the layers would stick together. The inner surfaces are not the prettiest thing to look at but it gets the job done. The arm and the body are both done in this way.
There is a step that isn't pictured but is really important. Before I merged the two halves of the body, I embedded a solid block of wood in the bottom rear of the main body that got sealed in place with more liquid plastic. This way there is a nice solid block that I will be able to drill into to attach the legs. The rear seam was also reinforced with a much thicker layer of plastic for structural support.
The two halves of the body and arm molds were then closed up and the bolts were tightened on the molds. Through a small hole in the middle of each piece I poured a few more cups of liquid plastic and spun each piece along the seam to marry the two halves together. I now have a solid hollow cast for the body and arms.
Its definitely a little more work to do it this way, but the final pulls are lightweight and durable!
The legs were much quicker to cast since they are solid. No slush casting required. I just filled up the molds, let the plastic cure and then removed the finished pieces. In all there were 11 pieces that got cast for a single turret. On to painting.
Materials used for this stage
Smoothcast 300
Plastic cups
mixer sticks
My goal with the hollow pieces was to create a shell that is roughly 1/8" thick. After doing a few tests with different ways to achieve this, I decided to slush cast each part of the mold separately and then merge the 2 halves to create a final cast. This helped to guarantee that there weren't any spots that were too thin.
By doing it this way I can add a little extra plastic wherever it might be needed. I built up the thickness in layer for each half of the mold. I made sure to not let the plastic fully cure between each coat so the layers would stick together. The inner surfaces are not the prettiest thing to look at but it gets the job done. The arm and the body are both done in this way.
There is a step that isn't pictured but is really important. Before I merged the two halves of the body, I embedded a solid block of wood in the bottom rear of the main body that got sealed in place with more liquid plastic. This way there is a nice solid block that I will be able to drill into to attach the legs. The rear seam was also reinforced with a much thicker layer of plastic for structural support.
The two halves of the body and arm molds were then closed up and the bolts were tightened on the molds. Through a small hole in the middle of each piece I poured a few more cups of liquid plastic and spun each piece along the seam to marry the two halves together. I now have a solid hollow cast for the body and arms.
Its definitely a little more work to do it this way, but the final pulls are lightweight and durable!
The legs were much quicker to cast since they are solid. No slush casting required. I just filled up the molds, let the plastic cure and then removed the finished pieces. In all there were 11 pieces that got cast for a single turret. On to painting.
Materials used for this stage
Smoothcast 300
Plastic cups
mixer sticks
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