13. Molding and Casting¶
Files¶
Overview¶
This week, I learned about the diffrent process for making a mold anc casting something in it. For my project, I designed a paw mold for the dogs to have their feet press into since I thought it would work similar to how we walk.
Group Work¶
This week me and my partners Amalia and Elle tested the diffrent types of material used for casting in my mold I made. Also we compared a wax milled mold to a 3d printed one. In my opinon the amber was the better casting material and the 3d printed mold seemed more worth while for me.
Designing¶
To make the paw print mold, I first found a stock image of a paw I could trace in fusion 360 that was then made into a 3d design.
From their, I extruded the design and added a circular base for all the parts of the paw to rest on.
From thier I went back into the time line to the begininng and made a rectangular prism at the center point which would intersect with the design I made.
Afterwards, I changed the extrudes of my sketches of the paw and puck to be cuts so that it would make the desired mold.
Finally I went back and fillet the paw and puck to give it a smooth finish
Painting¶
Because of how I made my mold, I needed to smooth out the layer lines of the print. I knew this becuase of what Mr. Torres said in the video on wensday.
To do this I used RTC-3D an epoxy coating material to smooth out my design. Heres the data sheet for it:
| Property | XTC-3D |
|---|---|
| Type of Material | Epoxy coating for 3D prints |
| Mix Ratio | 2A:1B by volume |
| Pot Life | 10 minutes |
| Cure Time | 2-4 hours at room temperature |
| Shore Hardness | 80D (approximate) |
| Viscosity (cps) | 1,000–1,500 cps |
| Color | Clear (can be tinted) |
| Useful Temperature Range | -30°F to 300°F (-34°C to 149°C) |
| Specific Gravity (g/cc) | 1.1 |
| Tensile Strength (psi) | Not specified |
| Elongation at Break (%) | Not specified |
| Flexural Strength (psi) | Not specified |
| Compressive Strength (psi) | Not specified |
| Heat Deflection Temperature | Not specified |
To use it, I poured the 2 parts A to 1 part B into a cup and mixed virogusly. Heres what it looked like:
After I was done mixing and painting heres what my molds looked like:
Molding¶
For the material I used in molding, I decided to use Smoothsil 940 to test out my mold. What I didnt know at the time of mixing and making mold is that a fellow fabber had left the part A of it out, casuing it to clump up and making an uneven mixture. becuase of that I got a less then ideal result for my first cast which ended up looking like this:
After that mold had been completed and removed, I then decided to use a diffrent material for my second mold. This time, I used PMC™-746 Clear Amber for my second mold. Heres the data sheet:
| Property | PMC™-746 Clear Amber |
|---|---|
| Type of Material | Urethane rubber |
| Mix Ratio | 1A:1B by volume (100A:90B by weight) |
| Pot Life | ~20 minutes at 73°F (23°C) |
| Cure Time | 16–24 hours at room temperature |
| Shore Hardness | 60A |
| Viscosity (cps) | 3,000 cps (mixed) |
| Color | Clear amber |
| Useful Temperature Range | -65°F to 180°F (-53°C to 82°C) |
| Specific Gravity (g/cc) | ~1.04 |
| Tensile Strength (psi) | ~500 psi |
| Elongation at Break (%) | ~200% |
| Flexural Strength (psi) | Not specified |
| Compressive Strength (psi) | Not specified |
| Heat Deflection Temp. | Not specified |
And heres what it looks like in the mold and out of it:
Reflection¶
This week wasnt very difficult, and I didnt run into any major issues during the week. It was fun to design and make a cast and then see cast become the design I made in fusion at the beggining. Overall this week was very interesting and Im thinking about implementing it into my final project.