Formula SAE Electric Low Voltage Electronics Boxes

Formlabs Form 1+ usage for custom manufactured PCB boxes

_Above: Form 1+ Printed Boxes Assembled_

I used two Form 1+ printers along with clear and black resin in order to print custom boxes for our FSAE Electric car to contain all our low voltage electronics. These boxes were designed in Solidworks CAD around exported 3D models from Altium Designer that included all connectors that the boxes had to be built around, as well as all components for clearances.

These boxes were originally scheduled to be sent out to Protolabs for a mighty cost of >$800, but I convinced the executive board to give me 3 days to print the boxes. So two Days, and less than a liter and a half of resin later, I printed out all 10 pieces for all boxes, with no failures, sanded and finished them, and passed them off to energetics for final assembly and PCB installation.

These prints had several optimized features for SLA Additive manufacturing processes. First, all of the boxes had an extremely small embossed groove for a rubber gasket for water proofing, smaller than a single thread of FDM plasic, as well as being more guaranteed to be waterproof. Second, we optimized them for flawless SLA, making formerly closed holes through holes to prevent large fluid pressures in cavities during the compression cycle. Finally, we optimized the boxes with fillets on most edges in order to forgoe needing extra supports to maintain edge crispness.

All pieces were manually oriented, sparse supports were generated with no internals, and then the rest of the supports were added manually areas that I recognized needed it. During the support removal process, since I was in a rush, I took some small chunks out of the gasket seal around the areas where our connectors stuck out. I managed to repair the seal using resin and a UV light, specifically a Nailspa, as recommended by Formlabs in the post-cure documentation. I then sanded to flatness and restored the groove to it’s original depth using a small file. The boxes were then then handed off to another engineer who then installed threaded inserts for plastic for McMaster-Carr for both the assembly and mounting hardware.

Also, embarrassingly, on my way to deliver the boxes I tripped and dropped a piece of the smallest box. It lost no fragments, so I was able to take the three pieces and epoxy them together. No one noticed. Seriously, the crack is in the pictures here, try to find it.

Future Work
I was able to convince our executive board to save the money we would have spent on the Protolabs prints for a future 3D printer of our own (hopefully one or more Form 2s), since for this project we were utilizing the library’s two basically unused Form 1+ machines. In addition, we also decided to print our Tractive System Active Light mounting and Brakelight and Dashboard PCB enclosures.

Below: Exploded view render of box assembly without PCB


That’s pretty good going - so that’s a fully-functional prototype rather than a space model?
I presume the production models will be injection moulded (and that draft angles et al are already built in)?

This is for Formula SAE Electric competition, which is a student competition to build formula style electric vehicles, so we don’t have to worry about full production. These are one offs, and as such, don’t have any draft or other traditional manufacturing required features.

Here’s a render of this year’s car.


That’s really awesome. Nice job, Teddy

What type of threaded inserts did you use? I haven’t had great luck in the past using threaded inserts and recommended designing pockets for nuts (see Adding screw threads to 3D-printed parts) but it will be great to know if there are some inserts that hold well in resin. Did you glue or seal them in at all?

Hey Jason,
We use thse inserts from McMaster-Carr:
They are installed using a press, no sealants or glue required as the gasket prevents moisture seepage.

Do note, we insert the inserts pre-post cure in order to prevent cracking upon insertion.