2021-05-09: Added parameters for 6mm hoses.

This project is available on GitHub as flower-box-hose-system and on Thingiverse.

As part of my balcony’s automatic watering system, I designed a few parts that can be used to bring water to every individual plant. Only some hoses from the hardware store are needed to put the 3D printed components to use.

To make the prints waterproof, please refer to my post on waterproof 3D printing.

1 Components

A selection of components is available to print. All of the are easily customizable by just changing a few numbers in the code to fit your needs (i.e. the type of hose that was available in your local hardware store).

The project files include parameterizations for hoses with inner diameters or 8mm and 4mm.

How to change the parameterization is described in the next chapter.

1.1 Sprinkler

Instead of just making a hose end next to a plant, I modeled a simple sprinkler that can be attached to a rubber hose. It has six holes in it through which water can escape and reach the plant uniformly.

Depending on the settings of your 3D printer, you might want to enlarge the little holes through which the water escapes prior to printing or use a small drill to enlarge them afterwards. Using the latter option, you can first check whether the water pressure is sufficient or too low before making any modifications.

1.2 Hose Clip

This clip is very useful for securing the hoses and other components in place. Prints fast and, als long as it is not printed in white, its barely noticeable in the bed.

To make the prints as waterproof as possible, I recommend printing the connectors upright on the print bed. This will decrease stability during printing (use crepe tape or a glue stick to make sure it doesn’t tip while printing) but will make the layers seal better with the hose.

1.3 Hose Connectors and Adapters

The connectors are also parameterizable and can be used to connect two hoses with the same diameter or as an adapter to attach a hose with a different diameter to the system. The sphere in the middle of the adapter is optional but helps a lot to get a tight grip on the piece when pushing a hose onto it or removing it.

1.4 Multi Channel Water Distributors

Since a small pump can already build enough pressure to supply water for multiple plants, it’s a good idea to use these splitters and lay a hose to each flower.

Water splitters are also parameterizable to have as many exits as you wish. They are available in two shapes. One looks cleaner but the other one will be better waterproofed. For more on that look here.

2 Parameterization

Note: You can add your custom parameterization at the end of the file Parameters.scad after cloning the GitHub repository flower-box-hose-system.

The following figure shows the main parameters that define the shape of a hose connector. This shape is changed in one parameterization file and can then be used for all of the components listed above.

All units are millimeter which is the standard for OpenSCAD. Note that c may be smaller than b.

Parameter	Unit	Description
a	mm	Inner diameter of the tube that will be printed.
b	mm	Outer diameter of the tube that will be printed.
c	mm	The diameter (minimum) at the most narrow part of the teeth.
d	mm	Maximum diameter of a tooth ring. This is recommended to be a bit larger than the inner diameter of the hose.
e	mm	Length of a tooth.
#teeth	-	Number of tooth rings.

The table below shows the values for the given example parameterization for hoses with an inner diameter of 8mm or 4mm.

Parameter	for 8mm hose	for 6mm hose	for 4mm hose
a	5.4mm	4mm	2.4mm
b	8mm	6mm	4mm
c	7.75mm	6mm	4mm
d	9mm	6.9mm	4.5mm
e	4.3mm	4mm	3mm
#teeth	4	4	4

While choosing the parameters, also pay attention to the fact that not all hoses are equally elastic nor do they have the same wall thickness. Especially the parameter d for the maximum tooth ring diameter has an influence on how waterproof the connection is and how easy it is to remove the hose.