3D Printing Hydroponics Part 2

This is a follow up article to my first article where I went over how to design a 3D printable modular hydroponics system. This system is made up of a bunch of twist together cylinders with length 15 cm, diameter of 10 cm and space for one plant trough measuring 5 cm.

The motivation behind this project is to overcome two of the main challenges to hydroponics. Construction — right now NFT systems are pretty tedious to build — and customizability — making modifications beyond the initial build are also inconvenient.

The one thing that needs to be combined with these modules to make it a functioning hydroponics system is an elbow connection. These connections are like little half doughnuts which connect different troughs and levels together so that you can have larger systems.

Each connection will have two circular openings with diameter 10 cm as well as a gap of 10 cm between them.

Step 1: The Tube

Our modules each have an exterior diameter of 10 cm and interior diameter of 9 cm, so we need the elbow connection to also have an exterior diameter of 10 cm and interior diameter of 9 cm. They are also going to have an inner diameter (the little gap between the two entrances) of 10 cm.

If you haven’t already, you might want to increase the size of the workplane to 400 mm by 400 mm by clicking on the icon in the bottom right corner.

To do this we are going to

1. Take a torus and in the drop down menu, change the radius to 5 and the tube to 2.5.
2. Give it a length and width of 300 mm and a height of 100 mm.
3. Duplicate it and set the duplicate aside.
4. Create a rectangular prism with length 150 mm, width 300 mm and height 100 mm and make it a hole.
5. Merge it into the torus, so that exactly half of the torus is cut off.
6. Group the two objects.

Step 2: The Hole

Now we need our joint to be hollow, so that water and nutrient solutions can flow through it.

To do this we are going to

1. Take the duplicate that we had set aside and decrease it’s length and width to 280 mm and it’s height to 90 mm.
2. Increase the radius to 6 in the drop down menu.
3. Slice a little over half of it off by creating a rectangular prism just as we did above.
4. Make it a hole and merge it into the larger half torus so that it is completely concealed.
5. Group the two objects.

Now of course, this basically lands us with a hollow torus that doesn’t have any openings. Since we want very precise openings that can fit over the other modules, we’ll do them separately.

1. Create a cylinder with diameter 90 mm and height 20 mm.
2. Make it a hole, rotate it laterally by 90 degrees, elevate it by 5 mm and duplicate it.
3. Merge one duplicate into the center of each of the circular faces on the torus cross section.
4. Group it all.

Now, you should be able to see the hollow cavity from both faces.

Step 3: The Connection

Just like we did for the previous modules, we need to turn this elbow connection into a tessellation. The easiest way to do that is by adding a smaller insert which comes out of one end which could fit into the other end of the connection.

And since, these elbow connections would also be connecting to the other straight modules, they should have the same style inserts as the straight module.

To fix this, we’ll add an extension to one end with the same exterior diameter as the interior diameter of the large tube (90 mm) and the same material thickness.

To do this, we’ll

1. Take a cylinder and give it a height of 20 mm and diameter of 90 mm.
2. Duplicate it and shrink it’s diameter down to 80 mm.
3. Make it a hole and merge it into the middle of the original cylinder.
4. And… group the two!

We can then rotate by it laterally by 90 degrees and merge it 5 mm into one end of the larger tube.

Step 4: The Screws

Now, making a screw is pretty challenging. Luckily, TinkerCAD has a communal repository of random shapes that wonderfully talented people have put together, one of which has made a screw.

In order to change the screw parameters, each shape has a handy drop down menu where you can just fill in whatever dimensions you want.

So, we are going to make the interior radius of the screw 18 and the exterior radius of the screw 20. We will make the inner thread height and outer thread height 1 and 2 mm, respectively. We’ll also give the screw two “turns” — or make it wrap around twice.

We will give the exterior screw a diameter of 100 mm and a height of 10 mm. We’ll then duplicate this screw and change it’s diameter to 90 mm for the interior screw.

The exterior screw will go 4 mm off the end of the extension, and the interior screw will go 6 mm off the other end.

And there we go, this combined with the other hydroponics style module will allow you to grow lettuce in your living room all year round in a convenient and customizable way!