A month off, Day 16: Stonefruit


Way at the beginning of The Month Off, I ordered a Rock64 and a Power over Ethernet hat from Pine64. I wanted to see how effective it'd be an alternative to the Raspberry Pi and PoE+ hat combination around which I had designed TCHeRI. I found that the combination did in fact work rather well, even if it was rather tall. In that post, I decided I could reprint the carrier body from which the board hangs to allow for the additional height.

One thing I really liked about the Pi Foundation's PoE+ hat is that it includes a small CPU fan. This simplifies the construction of TCHeRI so less cooling has to be built into the design. Pine64's PoE hat, however, has no such fan. Granted, Pine's board is much cheaper, but I'd gladly pay another $10 for one with a fan built in. I briefly considered buying another PoE+ hat and trying it on the Rock64, but I didn't want to deal with a potentially incompatible board.

So instead, I started designing a small fan holder to 3D print. Blender isn't a great tool for this kind of CAD work, although it could be if I started with a 2D path and extruded it instead. Instead, I sliced up and combined basic 3D objects, using a printable hat from Thingiverse and some printable fan covers as references for the bolt spacing. It's crude, but it works.

After four iterations, I had a design I was happy with. Printing in under an hour with no supports, the resulting design can use a 25 or 30mm fan. It can be mounted with two bolts to the Rock64, or regular standoffs. I posted the design to Thingiverse and Printables.

I also, finally, got around to printing a refinement of the carrier body too. Shaving of 2mm from my initial guess down to a total of 43mm wide seemed to be the exact size I needed. This is certainly quite a bit larger than the Pi version, but it still works.

I have one such carrier printed, but the print settings weren't quite right and the print came out with walls not bonded to each other. All the time printing with that cantankerous ABS means I need to relearn all over how to print with good quality PLA. I suspect either my flow rate is too low -- because I keep avoiding recalibrating the e-steps -- or the temperature was too low. I'm printing a second as I write this with different settings.

Provided I do get those settings right, I may reprint nearly all of those carriers. The bit of white in the middle of the rest of TCHeRI's looks was an artifact of a different color scheme to compliment the Pi400, and I'd rather remove it now that the Pi400 is also repurposed for other uses. I certainly have another black PLA to reprint them all once I get the settings dialed in. I haven't decided if I'll reprint them all at Rock64 size, or keep the mixed Pi size carrier bodies as well.

Another thing I did yesterday was spend an hour winterizing the garden and a further hour cleaning up some of the basement. I had been putting both of these off during the last few weeks to focus on more fun and interesting things. There's still a lot of that left to do, including some minor house repairs. I'm still hoping to getting to that this week.