Pneumatic connectors

Changelog

Feb 2026: Added 32x version of 3mm-3mm connector.

August 2025: added Clip_set_v3 (easier to open), Male_3mm_32x (to quick-connect 8 motors) and Male_3mm_4x (with 3.1 mm holes instead of 3.0 mm). Also added PneumaticConnector_O-ring_3x1mm_August_2025 which uses off-the-shelf O-rings instead of laser-cut silicone rubber rings, simplifying production.

March 2022: Initial version

Introduction

This series of 3D printed pneumatic connectors can be used to quick-connect (and disconnect) pneumatic devices such as cylinders, stepper motors and complete robots. The components are MR safe and designed for 3 mm and 4 mm pneumatic tubing.

Silicone rubber rings are used as seals in the female parts, to be laser-cut from 1 mm thick silicone rubber, and inserted mid-print after pausing at a specific height.

Variants

Male sockets are either 3 mm or 4 mm. Female sockets have two sides; besides 3→3 and 4→4 mm we also offer 4→3 mm. This is useful if your pneumatic manifold has 4 mm sockets while you use 3 mm tubing to the motors.

Connectors are 1x, 2x, 4x, 24x or 32x. The 4x male plugs fit in the 24x and 32x female socket. This is one exception to the rule that male and female parts must have the same number of ports.

Other variants can be created by adapting either of the two included Solidworks files.

Design

Cut-out view in connected state.

Cut-out view in disconnected state. Note the orientation of the seals (yellow): the larger face is on top and smaller face down, for optimal airtightness.

Rubber seals

Seals are laser-cut from 1 mm thick silicone rubber and inserted in the female parts mid-print.

3 mm sockets use rings with 6 mm outer diameter and 2.8 mm inner diameter. 4 mm sockets use rings with 7 mm outer diameter and 3.8 mm inner diameter. DXF and PDF files are attached.

Slicing

I use 0.15 mm profile with three perimeters (and no skirt) and leave rest at default. I use PLA.

We have to identify the correct moment to pause the print to insert the seals:

This is the last layer (Z=2.10 mm) before the seals are covered off.

Above you see the first layer (Z=2.25 mm) with the overhangs (dark blue circles) which will cover the seals. So a pause must be inserted at the beginning of this layer, which can be done by right-clicking the orange “+” button and selecting “Add pause print (M601)”.

If you have a Prusa Mini (early batch) and M601 is not working: upgrade your firmware and it should work.

Printing

If all is correctly set up then the printer will pause at the right moment so that you can insert the seals. Orientation: smaller face down, larger face up.

Ensure that the next layer is correctly printed over the seals.

Enlarge holes if necessary to right diameters (3 mm and/or 4 mm). Male part: all way through. Female part: depth 5 mm.

Insert tubes and apply glue. I use cyanoacrylate. The cross-shaped slots should be filled with glue to ensure a good bond.

In the male part the tubes should stick out around 4 mm. The “male tube cut tool” is useful to easily cut of excess tube.

Insert the clips horizontally, then twist it 90 degrees for the correct orientation. To enforce proper orientation you should have one clip with a notch, and one without notch.

There may be debris (stringing and other 3d printing artifacts) in sockets of the female part; use a small screwdriver to remove these.

The connectors are now ready!