A few days ago we as a team came up with a design for an intake system and looked online for some machanum rollers online. Turns out that they are out due to the number of people that also have the same idea. The reason that mecanum wheels work so well is that they don’t require any inwards force to produce a change in direction the wheels themselves solve that problem funneling them to the center of the indexer.
Anyways we have been brainstorming for a few days and after a but we looked at 3 d printing using this cad design (https://www.thingiverse.com/thing:2167). After finishing the print which took roughly 8 hours to make a set of two we found that to have a full set for our design it would take many more days.
This is what started our journey to using epoxy casts. After that day, my fellow peers had a 3 d printer at home that can print resin. Resin is great for making blanks due to its ability to be smooth. After that, we looked at different mold types. There are two main types, tin-Silicone, and Platinum-Silicone. We opted for the tin as it takes less time to cure but isn’t as strong (it isn’t necessary because we would only use each a few times more info here https://www.smooth-on.com/category/tin-silicone/). Turns out a mentor had some at home*
Our next big leap was finding a compatible epoxy/resin to use. We wanted something that’s faster than 3 d printing and more cost-effective per square inch. We set our parameters as the following, Must work with tin- silicone mold must be less than 8 hours of cure time, must have a pot life of 5 minutes or more, and must have a tensile strength greater than 3,000 psi. We can to the conclusion that Task 21 would work best for though premature (https://www.smooth-on.com/products/task-21/).
In our findings, this may not be the best way of doing it but it is a start and from the cast that we have done it has been within .003 of an inch in accuracy after shrinkage.
Team 1983 Skunkworks Robotics
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