Answered: VEX U: Finishing of 3D Printed Parts and Legal Plastics

We’re happy here at the University of Minnesota to be competing in the VEX U competition for the first time this year. Hopefully you can answer a few of our questions about 3D printed parts. According to :

We had two questions with regards to this:

1: What modifications to 3D printed parts are allowed after they are printed? Specifically, are we allowed to finish parts mechanically (ie, sanding, drilling out holes), chemically (using acetone to create a smooth surface), or are neither of the above legal?

2: You’ve already stated that metallic plastic 3D printed parts are legal for VEX U. In a similar vein, we were wondering if legal plastics include rubber and polyurethane-like plastics, such as those used in the Stratasys Objet line of polyjet 3D printers?

Thank you for your answers!

We’re happy to have you!

Simple mechanical finishing such as sanding and drilling out holes is permitted. Similarly, cleaning off your parts would also being permitted. However further changes which add functionality or chemical changes are not permitted.

Think of it this way, the intent of this rule is to allow teams to take advantage of 3D printing technology to make parts. The intent is not to to allow teams to print giant chunks of plastic and then use it as a raw material. The 3D printer needs to be doing the fabrication.

Do you have a link which has more information on this specific line of printers? We need more information in order to provide an informed answer.

Thanks for your clarification on the intent of the rule. This makes sense to us.

Here’s Stratasys’ page on Polyjet printing, and here’s a relevant document that can be found there. There’s also the MSDS sheet if that would help. We’re mostly wondering because there seems to be a grey line between materials like DigitalABS (which are effectively available for FDM printers) and more exotic materials like their simulated polypropylene and simulated rubber plastics.