I am getting my first 3D-printer (a Prusa CORE One) this week! I have tons of ideas that I want to get started with, but the most time-sensitive one is to make some self-watering planters for my balcony (so I can have time to grow some greens in the season). I wanted to do this without a 3D-printer last year, but I could never find any cases close to the right dimensions in the stores, and making the separator between the water reservoir and soil from off-the-shelf parts was not so easy with the cases I did find, so I hope I am able to make something functioning with my 3D-printer this year.
But I’m new to this, and I am looking for some advice to where to get started reading up on different concepts that will be relevant to this project. These are the things I am planning to dive into over the next weeks, and I am sure there are plenty of things I have not thought about at all:
-
Splitting and joining 3D-printed objects: The overall base area of the planter is too large for my 3D-printer to do in one go, and I am likely going to need four parts that I need to fuse together. I am thinking there are many “standard” ways of doing this, such as splitting with a jigsaw-puzzle pattern? I am also planning to simply glue to the parts together along the seam, and add an additional layer of glue along the boundary. Which leads to concerns about…
-
Water tightness: I know that making watertight prints is not the easiest thing in the world. The container should be able to contain water without leakage, and I am planning on reading up on all the ways to make the prints themselves as impermeable to water as possible. I am sure there are much to learn in terms of slicer settings here. In addition, I will look into different coatings I can finish it up with, such as a layer of water-proof wood glue. However, the water here will be absorbed by the soil and then by the plant’s roots, so this coating should be non-toxic.
-
Material choice: To begin with, I will only have PLA available, but I can get other filaments if needed. There are two immediate concerns I have about this: whether it is food-safe (for the same reason as above) and whether it is suitable for outdoors use. It will not be in direct sunlight, as I will build a wooden case around these 3D-printed containers, but the planters themselves will be, so it could get a little hot during Summer. Any other considerations I need to make?
-
Modelling the parts: I am already familiar with Blender, and planned on using it for the first project. I have FreeCAD installed, but zero experience. The shapes are simple, and I am sure I can draw up something in Blender in no time. But since I want to split them up, and join them ideally as flush as possible, will the models be precise enough? Dimensional precision is the main reason I’ve heard for using CAD-software over Blender for hobby basis.
This is pretty darn ambitious for a starter project. I say this as someone who is trying to get some fancy new 3D printable tomato cages going before the plants get tall and dangerous and I’ve been doing this for a while.
So you really probably want to de-complicate this, either by only making planters that are sized for the printer or finding a existing planter that’s the right size but not self-watering and designing just the self-watering part. You’ll probably learn a lot about the right way to do one this year and then next year you can attack the next generation of the planters.
The problem with printing in pieces is that you are going to have to make sure that the joints are strong enough for the weight of the soil. This is why using a ready-made outer container might help. In the same way, what you really want is something finger-ish or jigsaw-ish so that the pieces align themselves more easily and interlock.
You will probably want a fatter nozzle, otherwise this is going to take forever to print.
PETG seems to have worked fairly well for me for outdoor stuff? Coating or paint or whatnot is handy. You might want to look at the epoxy family? If you can print on the balcony, you might consider ASA which is totally fine for outdoor use with no paint.
FreeCAD is a bit of a learning curve? The thing that FreeCAD would make easier is a parametric model, where you say that you want a 400 x 400 x 300 planter. Except that if you are really serious about making large self-watering planters that are parametric, you are going to end up wanting to write code to make it all happen, which either means the Python in FreeCAD, the Python in Blender, or maybe just use OpenSCAD.
One avenue, which is also too big of an ask for this season, is making a multi-part model to cast the large pieces in concrete.
Another avenue would be to just design around the outside being wood and the 3D printed parts being brackets and jigs and connectors and the self-watering bits.
Thanks!
This is pretty darn ambitious for a starter project. I say this as someone who is trying to get some fancy new 3D printable tomato cages going before the plants get tall and dangerous and I’ve been doing this for a while.
Yeah, I realize it is ambitious, but my inexperience is perhaps making me think this will be doable from the get-go when it’s really not? We’ll see… I have a limited time before it no longer makes much sense to pursue this this year, so at some point I will need to cut my losses if I haven’t gotten anywhere.
So you really probably want to de-complicate this, either by only making planters that are sized for the printer or finding a existing planter that’s the right size but not self-watering and designing just the self-watering part. You’ll probably learn a lot about the right way to do one this year and then next year you can attack the next generation of the planters.
The design itself will be quite uncomplicated: a bottom container which will hold the water, and then some plates that will hold the soil, supported by the cups that will be submersed into the water that will be packed with soil and perforated to allow absorption. I was planning on lining these plates with some soil fabric so I could keep them loose, only with holes cut out for the cups. The reservoir will be filled through a PVC-pipe that leads from the top and down to the reservoir. I will then build this in with wooden panels (loose, as I otherwise would be unable to get the whole thing inside the shelf where these will go).
One of my big problems last year was finding anything of the right dimensions already existing. They will need to fit inside the shelf.
The problem with printing in pieces is that you are going to have to make sure that the joints are strong enough for the weight of the soil. This is why using a ready-made outer container might help. In the same way, what you really want is something finger-ish or jigsaw-ish so that the pieces align themselves more easily and interlock.
The soil container will have a quite broad base compared to the height. The plates that will hold up the soil will be supported by these cups as described above, and I can make these cups as broad as I need. Are PLA or PETG not particularly strong?
How do people achieve these interlocking patterns - standard tools in the software, plugins or do you do this manually?
You will probably want a fatter nozzle, otherwise this is going to take forever to print.
Oh, good point I didn’t think about, and adding this to be research list. I guess it is delivered with a 0.6mm nozzle.
PETG seems to have worked fairly well for me for outdoor stuff? Coating or paint or whatnot is handy. You might want to look at the epoxy family? If you can print on the balcony, you might consider ASA which is totally fine for outdoor use with no paint.
Cheers! Two suggestions for PETG, so I should probably order some filament already! And adding epoxy to my research list, thanks :) Printing on the balcony will unfortunately not be an option for now.
FreeCAD is a bit of a learning curve? The thing that FreeCAD would make easier is a parametric model, where you say that you want a 400 x 400 x 300 planter. Except that if you are really serious about making large self-watering planters that are parametric, you are going to end up wanting to write code to make it all happen, which either means the Python in FreeCAD, the Python in Blender, or maybe just use OpenSCAD.
I will need to look into parametric modelling it seems. Python I am very familiar with, so making use of that in modelling would in any case be a good skill to acquire. My instinct was just to add a mesh in Blender and resize to my desired dimensions and that would be good enough. My tolerance for the outer parts here is quite high, but for the joints I would want higher precision. OpenSCAD I have not heard about, so I will check out that.
The dimensions of the planter would be 120x40x40 cm ish (based on eyesight from where I am sitting).
One avenue, which is also too big of an ask for this season, is making a multi-part model to cast the large pieces in concrete.
Oh, interesting - that is far from anything I’ve considered. But yeah, not quite something I would be ready to tackle for this season.
Another avenue would be to just design around the outside being wood and the 3D printed parts being brackets and jigs and connectors and the self-watering bits.
It is not that far from what I am going for actually, but the self-watering parts is basically a water reservoir, so it would need to be a water-tight container. Had I only been able to find boxes of proper dimensions where I live, I would not even consider trying to 3D-print this. But they are either too tall, too deep or not long enough.
Yeah, see if you know Python, then OpenSCAD is not a hard jump? One of the reasons why I really like OpenSCAD is that libraries like BOSL2 have parametric joiners and snaps and stuff. And you could totally write modifiers for FreeCAD or Blender to do it, sure, but it’s a lot less trouble to get it done with OpenSCAD. This way your end-result would let you input the size of the bed and it would figure out how many sections it needs, etc.
Lesee… 120x40x40cm is a lot of plastic to print, even with a single printer running all day all night.
What I’d suggest is that you make the wooden outside for the 120x40x40cm shelf and make 20cm x 20cm x 40cm units. At which point you can make bigger multi-part modules. It might actually make sense to keep the cups separate because you could adjust the holes and stuff based on the plant’s needs. Whereas the reservoir section is going to be happiest as a single tub. But the important part is that if you are a few modules short, just add a spacer for this season. And it gives you more time to experiment on the tub and allows you to swap that out mid-season.
ETA: Hm, how thick do you think the walls would have to be?
Oh, that could be a much better solution. How would you design the reservoir filling system in that case? It would be difficult accessing the rear reservoirs directly, but I could maybe make something with cheap PVC-pipes. Ideally I would fill it from only one point, and I eventually plan to have some sensors measuring the water level in the reservoir(s)
You can always mock some stuff up and try it out in PrusaSlicer to see how long it thinks it’ll take?
Wall thickness potentially depends on the size of the object? I guess 2mm would the the starting point, fill one with soil, see how sturdy it feels. Complexity for 3D printing is “free”, kinda. A lot of the best container designs incorporate ribs to strengthen them without using up too much material. Given that the joins are the weak part, you’d potentially want that a lot thicker.
You also want to look at “vase mode”. Some of the fastest printing objects you can get on a 3D printer are where you design around the constraints of vase mode and then you can use a fat nozzle with thick layers to print really fast.
You can always print plumbing instead of using PVC pipes? I’ve definitely seen self-watering pots such that they just have a pipe incorporated into the design such that it just sticks up along the corner. So, worse case, each module has a watering port. If you want to get fancy, you could make a manifold such that a single pipe sticks up in the middle and fills 4 reservoirs, although the fancier the plumbing the more likely you are to have one of them get dried out faster unless your filling routine tops them off.
3d printed material is porous, so it will eventually fill with water and start leaking, but not a lot. You can solve this various ways though, just something to take into account.
Hard to gett a feel for what you want to build but there might be better solutions. The joints will be an other weak point. When assembling them though, I’ve heard using a candle or something similar to soften up the plastic a bit before fitting them together really helps.
Ambitious early project. I’d probably go with petg.
There are plenty of good tutorials / suggestions for general water tightness with regards to slicer settings. Water tight joints will be tricky. Consider sanding and then torching them. I’ve had good results with clearcoat spray after sanding pla. May work with petg too.
Curious why you didn’t go with xl for this? Cost?
Ambitious early project.
Hehe yeah, I would have gone with something else as my first project had it not been for the fact that I want these planters soon. I had hoped to get the printer earlier, but after asking for advice on my printer purchase here end of last year, I got a compelling advice to at least wait for first reviews before deciding, and by that time Prusa had a backlog on orders.
I’d probably go with petg.
Due it to being outdoors?
There are plenty of good tutorials / suggestions for general water tightness with regards to slicer settings. Water tight joints will be tricky. Consider sanding and then torching them. I’ve had good results with clearcoat spray after sanding pla. May work with petg too.
Nice, will check that out in more details! Are clearcoats typically non-toxic? Torching the joints sounds like a good idea - what would you typically use for that, a standard crème brûlée burner? I plan on making smaller prototypes to test out any concepts out before making a huge one.
Curious why you didn’t go with xl for this? Cost?
Cost is one major reason, the Core One was at the top-end of my budget, but it is not the only one. The Core One otherwise fit my requirements very well, and the XL would also not be able to print this in one go. This is by far the largest pieces I have planned on printing, and all the other prints on my “todo”-list will fit in it just fine. I wanted one with an enclosure, and I didn’t like the look of the XL with an enclosure, as it will be quite visible where it will be placed, and I’m the kind of person who would care. And I also believe the footprint of the XL is larger? In that case, I am not so sure if it would even fit on the designated space for it.
Yes due to outdoors. Even in low light, UV can add up and also, it takes quite some time, but even racemic pla does start to break down with aqueous exposure.
Recommend buying a dedicated butane torch (<$40) for print cleanup. Something in between a zippo and a crem brulee torch. Works wonders on removing and stranding on your prints.
Polycrillic finish is pretty inert stuff. Can’t imagine a sealant layer of it would be too toxic to plants or get significantly incorporated into any edible plant materials. I use polycrillic coated pla for weighing out coffee beans.
@cyberwolfie @Imgonnatrythis agree that Freecad learning curve is steep. I balked and ended up using Fusion360 (non commercial). I found it to be more friendly and have tutorials I liked. I like the idea of using an LLM to code in something like OpenSCAD though.
Did you try FreeCAD after v1.0 release? I heard it got more intuitive with the release. I would prefer to stick to FOSS tools, and Fusion360 does also not seem to have a native Linux version?
But yeah, it is the impression I have gotten that FreeCAD is not very easy to get started with and why I thought to stick with what I know (Blender) for my first project.
Freecad is well worth your time. Yes it is a bit unwieldy at first, but once it starts to click you can be fast. For me, the most time consuming aspect is usually wrapping my brain around what the model should look like. Achieving it is then either trivial or you quickly look it up if it isn’t. There are lots of good tutorials.
If you’re trying to design anything functional, you should really go with a parametric modeller.
