The 3D printing thing escalated quickly.
I figured out how to make robot wheels.
- Print a mould. I used PETG as it polishes up nice and holds the mould release agent well. This is for a custom robot wheel. The piece in the middle with come with the urethane when I break it out. The center fits on a 1/2″ hex shaft and the little notches are to hold the urethane better. I used Smooth-On Universal Mould Release for the agent.
![](https://atomicalex.com/wp-content/uploads/2022/01/IMG_3271-1024x768.jpg)
2. After spraying the mould with mould release, I made up the urethane rubber. I used PMC-744, a 44A Shore compound. It’s quite floppy, which is perfect because this wheel needs to be ultra compliant.
![](https://atomicalex.com/wp-content/uploads/2022/01/IMG_3277-1024x768.jpg)
3. The urethane is a 2:1 mix, and I made 75gr which turned out to be twice what I needed. I need to get better at estimating how much resin I need by doing volume calcs or just filling with water and weighing.
![](https://atomicalex.com/wp-content/uploads/2022/01/IMG_3272-1024x768.jpg)
4. Next step is the actual pour. I have the mould sitting on a silicone release pad. Parchment paper also works.
![](https://atomicalex.com/wp-content/uploads/2022/01/IMG_3273-1024x768.jpg)
5. Next is the poured mould. I have to strike it off to make the sides level and get the rubber evenly distributed. I could pressure cast it, but I do not have a pressure pot. I sometimes vaccum the castings to get the air out, but not for this test wheel.
![](https://atomicalex.com/wp-content/uploads/2022/01/IMG_3274-1024x768.jpg)
6. Last step is to cover it up. Urethanes STINK, so controlling the environment is really useful. Thankfully I have some leftover Gladware to do the job. A few of the Gladware containers are really handy if you craft a lot.
![](https://atomicalex.com/wp-content/uploads/2022/01/IMG_3276-1024x768.jpg)
I’ll post up the wheel when I pull it tomorrow!