Self-Watering Liner for Potted Plants (Parametric)

I made this design to add self-watering or self-draining to any round planter that you already have.  It has a tapered shape, with variables for the top and bottom diameter.  After several design iterations, I liked the simplicity of an all-in-one 3D print that eliminates spills if you accidentally overfill.  

Is It Watertight?

It should hold water, but success may vary some from printer to printer.  I have a moderately tuned Voron 2.4 and I did not detect any leaking water after a year and a half of use.  If you have any doubts, I recommend adding some water to an empty liner and observing for a few days.  

If you have trouble you can make several adjustments.  For maximum waterproofing, try using a sealing or waterproofing product on the bottom exterior.  

Since the model is parametric, you can adjust thickness for walls and floors.  The idea is that more layers and walls creates a better barrier against water.  In my design, wall thickness for watertight areas is thicker by default.  (Other walls are thinner to reduce print time.)  

Be sure that you are not underextruding.  In fact, you can increase your extrusion multiplier to purposefully overextrude.  This will help to fill in the tiny gaps between layers and perimeters.  

Bridging for the Reservoir

I addressed the large amount of bridging for the water reservoir with sequential bridging and a grid of bridge supports.  The maximum bridging distance can be set manually and parametric design fills in the supports.  

It is important to check the alignment of the two bridging layers in your slicer!  I have a photo in the picture gallery illustrating how the bridges should be formed.  In PrusaSlicer, you can force the correct orientation with a height range modifier to select the layer, and then adjusting “Bridging angle”.  If you only see one bridge, adjust the “layer” variable in the f3d file to match your slicing layer height.  

Draining and Wicking

For the wicking and draining ports at the bottom, I have used sphagnum moss and strips of kitchen sponge.  The sphagnum moss drains the quickest but does let some soil through when watering from the top.  You can adjust this by altering how tightly you pack the moss into the drainage holes.  A kitchen sponge drains more slowly but keeps more soil from migrating to the water reservoir.  

I cut strips from a foam mat and set them in the fill port to check on the water level.  Most closed cell foam (yoga/camping mat, or pool noodle, …) should easily float.

Notes

Do be aware that ceramic planters will have a certain amount of non-uniform dimensions.  For instance, the bottom of my planters were not flat, causing my liner to wobble around and not sit straight.  I added three adhesive backed felt pads to the bottom of the liner to help it sit flat.

If you have a container with a standard size, leave a comment with the interior dimensions (height, top diameter, bottom diameter) and I can add an stl file to the downloads.  I will try to accommodate requests as I have time.  

A note on Fusion360:  I tried to make the design robust to variable changes within reason.  However, you will likely need to rerun the two revolve operations in the fourth group in the timeline.  I have not tried every permutation of variables, but redoing those two operations resolves complaints from F360 and any unexpected outcomes that I came across.  

Thanks for visiting, and enjoy!