3D printable radio case

One of our students created this radio case to hold the power connector in. This can easily become dislodged during a defense crossing, so it could prove very useful. Attached is the file to print it and a photo of it mounted in our 'bot.

The round ears on the corners are to prevent warping during printing. Just cut them off when it’s done. The bottom is open to allow attachment of the radio with fasteners, velcro, etc… The radio just snaps in.

Happy printing.

Radio Case With Warp Protection Circles.zip (94.9 KB)
radio case.pdf (181 KB)

Radio Case With Warp Protection Circles.zip (94.9 KB)
radio case.pdf (181 KB)

Did you guys do this because of how the internal’s of the radio are open to the outside or is it for mounting puposes?

just to hold the power connector in

Please let this student have my thanks, we didn’t realize we had this problem until yesterday. We were doing a promotional event and after we went over the rock wall about 15-18 times the power connector simply fell out. This will be very useful. I hope that the student doesn’t mind if I edit the drawing a little bit to make it more suitable for mounting :D.

I’m not sure we ever connected anything to our router’s power port. We’ve been using passive Power Over Ethernet from the beginning. The network cable isn’t prone to coming out due to vibration. My feeling is that any shocks that would dislodge it are likely to dislodge the innards of the router as well.

Don’t quote me on this, but one of our mentors told us that it was against the rules to use POE with the router for competition…

Ask that mentor to quote the rule which prohibits it. Then have him read the second paragraph in the blue box following <R43>:
Note that this prohibits using any POE Injector device to power the
radio, but does not prohibit using any PASSIVE CONDUCTORS to
inject the VRM power into an Ethernet cable plugged into the radio port
labeled “18-24v POE”.

We took a short Ethernet “port saver”, exposed the wires in the middle, and spliced in a power pigtail to go to the VRM.

Sounds like a great solution. We wanted to do that, but didn’t, because we (apparently mistakenly) presumed that the 12V from the VRM wouldn’t successfully power the device in the “18-24v POE” port – sounds like you’ve found that putting 12v into the “18-24v” port works A-OK?

The port is labeled 18-24v, but the label on the bottom of the router says 12-24v. The open-mesh web site says it’s compatible with 12-24v passive POE. Following the suggestion in the <R43> blue box commentary works fine.

If we had a 3D printer, a radio mount with a built-in strain relief for the Ethernet cable is something I’d be asking our students to investigate.

can you give more detail on this?
What wires to splice into, etc?

Also, please give us a specific citation to the “port saver” you used, for future reference.


Martin Haeberli
(de-)mentor, FRC 3045 Gear Gremlins (formerly SWAT)

There are eight wires in an Ethernet cable, connected to pins 1-8 on the connector. The Ethernet signal is carried on the 3/6 and 1/2 pairs (green and orange wires). For passive POE, pins 4 and 5 (blue) get +12 volts, and pins 7 and 8 (brown) are ground.

(A wire pair is actually one wire of solid color and one white wire with a like-colored stripe.)

You can find more information by doing a web search on “passive power over ethernet”.

The ones we are using are from a prior year’s First Choice, part number FC14-022. I’m pretty sure they are the same as what is available here: https://www.estoprobotics.com/estore/index.php?_a=viewProd&productId=27

Any short Ethernet extension should be usable.

As a proof of concept, I also pulled apart a cheap Ethernet coupler (similar to http://www.cablewholesale.com/products/network-phone/phone-adaptors/product-mc-8p8c-st.php), stripped the appropriate wires inside it, and soldered on power wires that exit the coupler through a small hole I drilled in the bottom. It would require two Ethernet patch cables to use it, one going to the roboRIO and one to the OM5P.