JamesO's Garage Build Diary


#1

Hey Nerd Farmers!
I’ve been interested in building a food computer for a while now - so I went for it. I don’t have a ton of photos of the frame or mounting some components of the motherboard assembly, but want to contribute everything I’ve learned from the past two weeks of building, and everything that’s to come.

I have been posting some odds and ends on my new twitter @workshopgarden, so feel welcome to follow!

Where to start?


Materials

First, I had to round up all of the materials. Luckily I live near a Home Depot, so between that and Amazon I was able to grab 2/3 of the parts (The rest of the stores shipped pretty quickly, but I think I’ve been spoiled by Amazon Prime).

Please Please Please Read If you’re considering building a PFC: Unlisted Materials
The BOM is great. But it is missing a thing or two. For example- don’t throw away your scrap punched angles, since you’ll use them to mount the humidifier to the motherboard (if you choose do it it this way, but @silversson has worked on alternatives :slight_smile: ). Also, you’ll need to pick up two lengths (maybe a foot and a half worth each?) of six channel ribbon/hookup wire, as well as at least five grove-jumper cables (unless you’re comfortable messing with normal grove cables), an assortment of grove cables (I bought two packs of long and a pack of short off of Seeed but that’s probably huge overkill haha), and some sockets (you use nine but you may want to practice soldering so you might order more than one pack of ten to be safe).
We now return to our regularly scheduled Build Diary


Mainframe

Then it came time to get cutting! I don’t have solidworks to view the files and check for dimensions, but I do have Fusion360- so I used it to create schematics (messy and confusing for a first go, but still useful personally) to get dimensions off of. They look like they are to a some kind of standard scale, but I really just intended for them to be used to grab some quick dimensions.

motherboard panel drawing.pdf (91.9 KB)
base board drawing.pdf (35.0 KB)
mobo dock panel draw.pdf (72.0 KB)

I had the base board vertically on the leftmost edge, using the bottom and left milled edge, and put the motherboard horizontally above it so I could use the left and top milled edge. The mounting board for the motherboard used the bottom edge and the right side of the base board cut as sides (I have a picture I’ll upload in a bit). I noticed that if I cut it this way, I’ve only used half of the 4’x8’ PVC board (with enough scrap to make the six feet and experiment with mounting mechanisms), so if I wanted to, I could build another set of PVC components. Cool!

For the cuts I used a tablesaw with a wood blade (luckily we had a family member who had one they didn’t use). Since we only use half a board per PFC, I cut it down the middle to make it easier to work with.

I only have a 4" diameter holesaw and a 2" diameter holesaw aside from normal drill bits, so they have been my set for this whole project so far. They’re not perfect always, but they work pretty well.

To cut out the space for the motherboard in the mounting piece, I drilled some quarter inch holes on two of the corners, and then used a jigsaw the cut the sides and meet at the other corners.

Cutting the punched flats was a little more fun. Aside from the table saw I don’t have access to a ton of shop equipment, so I grabbed a powered reciprocating saw and went to town. Also I must confess I don’t have a proper workbench (mycostco folding table is spacious, though), but metro shelving, a plank, and some c-clamps ended up cutting it (literally and figuratively).

Assembly went pretty smoothly too, except where it didn’t. I knew a little bit of coercing would be involved, but I used my hand tools a lot more than I expected and I’m proud of it. Weatherstrip tape went on pretty easily too.



Motherboard

Now comes the fun part - The motherboard! I have a little bit of experience with electronics, managing and connecting wires, so I had a lot of fun here. I started with the AC Relay module (snapping off of the tabs was a pain in the butt but I eventually got it), but quickly found that I was missing some of the grove connectors and six channel ribbon cables needed, so that’s at a pause point for right now.


I’ve modified the project box and mounted all of the air exchange components onto the motherboard while I’ve waited for those parts (as I said before, I don’t have exact hole sizes so it didn’t perfectly line up with the holes on the motherboard, but it was close enough). I got sick of hot glue so I just taped the air pump to the top of the exchange box, and its held :slight_smile: The fans went on without a hitch, then I used some hookup wire to connect the fan headers to a grove header and e-taped it up.

As for the raspberry pi…
I’ve talked about this a few times before, but I’ll consolodate it here. I bought a pi3, and unfortunatley the kernel provided won’t boot on it. But the screen does function, and I’ve heard from a moderator on the raspberry pi forum (I’m new to the Pi so I can’t speak personally to this), that an operating system updated on a pi2 might be transferable to a pi3. I would lose the screen software, but I can always add that back.
For now, I bought a pi2 and will be using that, possibly to experiment with ‘porting’ the v1.0 software over to the pi3. But version 1.1 will be released in coming weeks according to Jake Rye, which will be a different kind of setup, but will be released for the pi3.

And thats most of my work so far! I’ll post again once I’ve made some more progress on the electronics setup, but I’m taking my time to make sure I wire everything up correctly. Please let me know what you think, and feel free to tag me with questions @JamesO.


Grow Box Dimensions
Toby's Build Diary
#2

While trying to mash together the AC relay module just now, I ran into the same thing. A little bit discouraging to get almost all the way but not be able to finish it. There doesn’t seem to be a lot of responsiveness in the hardware GitHub project, but probably still worth raising an issue for visibility with new builders.

Did you fit the relay board in the box behind the receptacles? Is that what’ we’re supposed to do? I’m going to have to snip the leads shorter…


#3

I was able to fit the relay board in, but they are a little jumbled :laughing: I remember thinking to myself that the whole “strip one inch” thing would totally cause a short somewhere so I ended up trimming them.

On your other note, I think I’ll make a separate topic for errors in the 1.0 directions. For example I recall one of the assembly portions with the punched flats listing one of the parts as 31 inches instead of the actual thirty I had cut, and getting too nervous haha.


#4

Was it this line here?

Use the 2 30 1⁄2” punched angle lengths as the vertical posts on the outermost electronics chamber side, making sure that the end of the length with the cut through a punched hole is towards the top.

I don’t see 30 1⁄2 listed on the cut list, only 31 1⁄2. I probably won’t get around to anything tonight, but I’d like to take a stab at starting the frame tomorrow because it seems everything relies on Grove cables which I don’t have. Seems to have gone pretty smoothly for you though.


#5

Whoops! My mistake, you’re right. Cut to 31 1/2


#6

For my own uses, I’ve forked the repo and incorporated Sean Lerner’s work to convert the PDFs to markdown to make them a little more accessible. I don’t know why the gro-hardware repo is inactive, but still seems like a valuable place to keep things, and more importantly share things. If you’re compiling mistakes, let me know so I don’t have to make the same ones!


#7

Have you found any need for a laser cutter or do you see the need for one in the future? If so, what components will be in need of cutting?


#8

Hi Ben! Personally I ended up not using a laser cutter, but it you were to have access to one I would have used it to cut the acrylic pieces. I used a router, which is tricky, but still doable.