Kiwi Food Computer Build Diary


Hi all - so despite joining the community several months ago, we (Ashley and Ray) only just managed to start building our Food computer as the raw materials are pretty expensive or hard to come by down here in New Zealand. But… Building started on Saturday and we’re super excited all over again. It’s been great reading all the lessons learnt from the other build diaries so hopefully there are a couple of useful pointers that come out of our own build for our successors! I’ll try and keep this as up to date as possible and if there’s anything in particular any of you would like to see in more detail, please let me know and I’ll take more photos!


Starting the day counter from the day we finally got all the raw materials together.

Day 1 (Saturday): From the outset we deviated a little from the BOM to reduce costs.

  • Rigid PVC is literally 10 times more expensive here in NZ than it is in the USA, so we’re using Laminated Chipboard for the base. We don’t happen to have a CNC router in the garage so we’ve found a local firm to do the machining for us. Of the rigid PVC parts, the plan was to only get the motherboard plate machined since that had the most cuts in it. Unfortunately due to some miscommunication that we haven’t managed to get to the bottom of somehow we ended up with the vertical motherboard plate machined instead so on the plus side we don’t need as much laminated chipboard!
  • Punched angle just doesn’t seem to exist in NZ so we’ve ended up buying 20mm wide, 1 mm thick aluminium angle instead and we’re planning on cutting the holes we need ourselves.

In case anyone else is intending on building in NZ, we’re putting together our own fork of the OpenAG GitHub repo with the changes we’ve made to build in NZ, such as updated BOM and any instruction changes.

So having cut up the laminated chipboard:

The next step was cutting up a truck load of aluminium angle and then drilling lots… And lots and lots and lots and lots… Of holes.


Day 2 (Sunday): Luckily I checked my measurements before I drilled more holes today. Now I’ve thought about it it’s obvious but in case anyone else isn’t using punched angle and on the off chance this hasn’t occurred to you yet… If you’re using a set location from the ends of your angle for your holes, the holes need to be substantially larger than the bolts you’re using. We’re using M6 bolts but if we use 6mm holes, which would be my obvious first inclination because I like precision engineering, then the frame just won’t fit together. The problem is that with every 3 angle joint there are variable offsets of the holes because of the thickness of the angle and there isn’t one convenient measurement from the end of every angle that will let all the holes line up. So, my solution for this is to drill 8mm holes instead of 6mm and they’re located 8mm along and 8mm in from the outside corner of every angle. I’ve done one test run with three angles and it’s looking good so far. It grates with the engineer in me but it does the job. The only other option would be to uniquely drill every single joint and I just haven’t got the patience for that. I’m writing this away from my garage / workshop so I haven’t got a photo or diagram but I’ll add one when I get back home later today to make this more obvious.


I’ve just found that the original CAD drawings show this problem. As you can hopefully see below, the holes from the punched angle don’t actually line up, hence the bolts in the original design needing to be smaller than the punched angle holes:


Where in NZ are you guys? I am based in Wellington and very keen to get in to the food computer movement!


@KiwiRay you could do two things :slight_smile:

One hole is misaligned so you could re-drill the hole to fit. Also other option that I used is to put the angle bar into a vice and take a hammer to it. Also was quite fun :smiley:


@bradbnz we’re also in Wellington! What are you thinking of doing? Definitely happy to help with anything I can.


@silversson Thanks. Most of them worked ok with the oversized holes. There were still a few awkward ones though that needed some creative drilling to extend some holes sideways :slight_smile:


Day 3 (Monday): this is probably going to be last post for a few days since we can’t really do many days after work. We made good progress though and now have some of the frame up. It took some creative drilling to make things line up in some cases and the plan is to get the frame together on all the corners to make sure it works and then drill through the aluminium and the base at the same time to bolt angles down in the middle. I’ll let you know how that turns out!


Btw, in case anyone else is using angle that hasn’t been pre-punched, I found making a template to put the holes in consistent places was helpful. Mine looked like the following and fit in to the corner of the angle against either end. You poke a pen, or smack a punch, through the hole to mark where to drill.


Day 4 (Saturday): It’s been a few days since we’ve managed to get together to continue on our food computer and with real work getting in the way I’m a little late posting this update.

The day actually went pretty smoothly. We decided that one of us should start on the shell while the other continued on assembling the rest of the frame since we’d cut all the holes and hopefully the rest was therefore just a meccano set.

Frame: I got some shorter bolts (15mm and M5 rather than M6) to replace the longer 20mm M6 bolts we already had since they were sticking out too far and would have interfered with the shell. I made one rooky error putting it together which leads to a short word of advice. If you’ve customised bits of the frame by extending holes in any way, then number them and put them back in the right place afterwards! Seems obvious in retrospect but I only realised when I got to the last piece and then had absolutely no idea where the piece I actually wanted that fit was instead because all the holes were covered up by washers.

Eventually got all the frame together and it’s pretty satisfying when you tighten everything up and it’s suddenly really sturdy :slight_smile:. It did take longer than expected though.

Shell: NOTE: THERE’S ONLY ONE WAY AROUND TO GET ALL THE PIECES YOU NEED OUT OF THE INSULATION WITHOUT HAVING TO STITCH PIECES TOGETHER TO MAKE A SIDE. We really should have drawn it out beforehand :frowning:. It’s not actually the end of the world if you get this wrong but it’s just slightly more difficult to put everything together - more gluing. Also, turns out using the table saw to cut the insulation creates really neat cuts and really straight edges. It also creates an amazing amount of practically invisible PIR dust in the air so having learnt this the hard way after the first cut - either keep your dust mask on for ages after you cut it, or use an extractor! Or cut it by hand - though the result isn’t quite as nice.

We didn’t get as far as sticking the shell pieces together, but we have now got them all cut. The photo below is the result of dividing the sheet up the wrong way in the first place (the lines just below the top of the window are cuts so this isn’t one sheet with a hole in it but two with blocks cut out that line up). It’s definitely not a disaster, just means more aluminium tape will be needed later and more glue will be needed to stick it all together which makes for a slightly less sturdy shell.

Turns out the old adage, “measure twice, cut once” is totally true :slight_smile:

That’s it for now. Ashley and I are out of town on work for a few days. Hopefully next update on Thursday night.


Day 5 (Saturday): We managed to get 3 hours in today and got the frame finished (needed a little more tightening and then drilled a couple of extra holes through the angle and base board for a bit more rigidity). We also managed to get the polycarbonate side panel on with the magnets. For the record we went with magnets half the size and WAY fewer of them than the BOM states - there’s a massive amount of over-engineering there. This saved us a fortune in magnets - those Nimodium magnets are NOT cheap. I’ll keep a record of how many we use as we go on but so far we used only 6 hold points on the polycarbonate back panel (which means 12 magnets in total) and we glued them in with “All fix” glue.

Note: the magnets are more fragile than they appear. Because they’re really powerful, accidentally letting go of one and it snapping back on to the pile of magnets broke it in half. Be warned!

Last but definitely not least, we got all the shell insulation glued together and held together with masking tape.


Day 6 (Saturday again): Busy periods at work aren’t really giving us any time during the week but we managed to get another 3 hours in on the weekend. The glue had set on the insulation shell which was great news. Also it had set on the magnets holding the back panel on and the glue seems strong enough to hold when taking the back panel off. I can therefore confirm that only 12 magnets in 6 locations (and the magnets were WAY smaller than the spec, specifically: D10x1.5 mm N45 Disc Neo Magnet) is plenty to hold the panel on.

That then brought us on to the Corflute. Having learned our lessen with the insulation, we planned this one out better, down to which cuts we were going to make in our sheet and which measurements were the important ones for each cut. As a result it all went pretty smoothly, it fit together really nicely and looks great! We used spray glue as advised in the instructions and it seemed OK at the time. We’ll see when we next get back to it (hopefully Wednesday evening) whether it will hold. Again, we used copious amounts of masking tape to hold everything in place while the glue sets. Also, worth mentioning that as per the instructions, we used aluminium tape to cover all the exposed insulation edges (so bottom and left of the shell, as well as the joins between insulation pieces. The end result looks like it belongs on the international space station :slight_smile:

Oh we also sprayed the acrylic panel with the frosted glass spray paint. That stuff is amazing!! Looks very cool. Only aesthetic but a nice touch :slight_smile:

We should get back on to it on Wednesday and I’ll try and be a bit more prompt on getting the post up next time!


Day 7 (Wednesday): We managed to get some time in after work yesterday and made some great progress.

We took all the masking tape off the shell and although most of the panels stuck, the right hand end panel basically hadn’t stuck much at all and some of the edges on the other panels were iffy. We’d used spray glue to fix them on as per instructions, but if we were doing it again from scratch I think I’d just use the same All fix glue we used for the magnets. So we shoved a load of that glue in the various cracks and surfaces that were coming off and re-taped it. Fingers crossed it should all be solid next time.

We’d got the acrylic and polycarbonate pieces machined for us which meant they looked great but sadly the holes machined in for the bolts were never going to line up with the holes we’d created in the angles. So, after re-drilling to fit these went on really nicely. Btw, if you find yourself needing to drill any of those plastic sheets I recommend sandwiching your plastic sheet between a couple of wood off cuts before drilling through the wood and plastic at the same time. This way you can clamp your plastic down with scratching for the surface and you get a clean drilling action through the plastic as well without chipping any of the brittle surface.

The physical bits are now basically done! :slight_smile:

We even managed to get started on the electronics! This is where it starts to really get fun for me :slight_smile:

Thankfully we didn’t make this mistake but worth pointing out: The power supply can be configured for 120V or 240V - make sure you change it (just flick the switch on the side) to match your local mains voltage! - that’s 240V in New Zealand.

So we cabled up the power supply and tuned it to exactly 12V. All pretty easy so far! Next bit’s going to get more complicated when we get on to soldering up the Arduino prototyping board and creating our own 4-way mains relay. Stay tuned!


Day 8 (Saturday): So, even MORE re-gluing was required to keep the Corflute on the shell. If you’ve reached that point in your build, I suggest you don’t bother with the spray glue and just go straight for something more… Sticky. Our tube of “All Fix” is now basically empty, but… Pause for effect… It’s stuck! Whoop woop. :slight_smile:

(See: No masking tape holding it together anymore :wink: )

I’m wondering whether we should follow Jussi’s (@silversson) lead and put some trimming round the outside of the shell to tidy up the corners but it’s actually reasonably tidy and clean at the moment, and I like the idea of just the solid white shell - maybe next time I’ll use solid white polycarbonate or something instead to make it even more spacey :slight_smile: . Might change my mind if any of the corners start coming up.

Ash also made a great start on the lighting rig and I had a go at creating the kiwi version of the 4-way mains relay. Let’s just say Ash made lots of great progress and I didn’t. There’s way less space on the inside of a cheap 4-way than I thought so I’m going to have to put a bit more thought in to the design of it before I carry on with it.


Day 9 (Saturday): Time to really get our heads out of materials and physical construction and into electronics. Turns out we’re short some grove connectors so while those are on order we’ll have to wait on soldering up the Protoboard shield for the Arduino. In the mean time, Ashley pretty much finished the lighting rig which looks awesome!

Since we haven’t got punched angle and our base is slightly longer than the original design (because of the size tubs that were available in New Zealand) we’ve had to improvise slightly on how the lighting rig is held up. So we’ve gone for the screw rods at both ends instead of just one and created slotted tabs for both ends of the lighting bed to slot in to the rods.

Question: Would there be any cause to change the height of the lighting rig at any time once we’re growing plants?

If there is, or I get no response to this, I’ll create some extra holes on the vertical angles so we can move the lighting rig up and down. I’m basically wondering whether it would be better for early growth, or just short plants frankly. Any thoughts or comments appreciated!

In the mean time, I started putting together the other electronic components.

  • EC sensor board :white_check_mark:
  • pH sensor board :white_check_mark:
  • Water temperature sensor board :white_check_mark:
  • DC power control relay :white_check_mark:

I knew my years at secondary school and university soldering and heat shrinking were going to pay off at some point!

Note for others: The written instructions regarding the DC control relay are incorrect. There is no 6-way cable to plug in to the relay so go with the electronics visualisation instead and use the two 4-way plugs.


Day 10 (Sunday): The grove connectors arrived so we got on to lots of soldering today. It was going pretty well and then we suffered our first set-back. In the process of soldering one of the headers on to the protoshield I managed to melt the corner of the header in the middle of the board with the side of the soldering iron. In the removal of that header however we managed to melt pretty much all of the other headers we’d already soldered on. So, that board is going in the bin. New board arrives in a week.

On a more positive note, the lighting rig is now completely finished, complete with LED strip around the face. There’s not a lot in the instructions about how that’s supposed to be put on, especially around the corners! I’m not 100% convinced about our solution but you can judge for yourself below.

PS any thoughts on the lighting question in my last post? If no response by the next session, I’ll start drilling holes.


Looks great :slight_smile:

It would not be a DIY project if at least one proto shield needs to be thrown into the dumpster :slight_smile:

I recommend to use hot glue to secure the led light strip. I had mine drop off in a week… Adhesive that is at the bottom of the strip is not the most sturdy :slight_smile:


Yep, you’re right :slight_smile: it’s already coming loose:

I’ll definitely go for the glue gun.


Day 10 (Sunday): It’s absolutely freezing this weekend here in Wellington (mid-winter in the Southern Hemisphere). To combat that we’ve now got two electric heaters running in the garage. Unfortunately it would seem that our fuse box didn’t like that. My house is rented and so this is the first time I’ve even looked closely at the fuse box and it turns out it’s an old school fuse box, not circuit breakers, so there’s no quick fix. That’s it for the day :frowning:. Off to work out which fuse needs changing and to buy some fuse wire… or more likely get the housing management agency to get an electrician out to do it - if I’m lucky they’ll take the opportunity to change it out for a circuit breaker.