Adding hoses to 3D printed parts

One of the challenges of this project has been how to attach hoses to holes in 3D printed parts.

This might seem like such a mundane problem -- surely we can get something to work. And indeed we did. We got many things to work, including:

• Gluing hoses directly into the parts
• Gluing pieces of brass tubing into the parts and pushing the hoses onto these
• Tapping the parts and screwing on threaded hose barb fittings

But the challenge is this. Given a 3D printed part that came off the machine, can you figure out an easy way to attach a hose that is not dependent on whacky techniques and skills, so the stuff can be sent to people as a user-friendly kit?

Today I'm trying the technique of 3D printing 10-32 internal threads directly into the parts, and then screwing in plastic barbed fittings. This is an example of one of the tiny parts of the probe, with a threaded hole, printed using a 0.4mm nozzle at 0.1mm layers in ABS on my Prusa i3 MK3S:

This is an Eldon James A1032-1-209BN fitting, that goes from a 10-32 UNF thread to a 1/16" hose barb:

And these are the parts screwed together:

You could imagine putting a tiny smear of silicone or glue or whatever to make the seal super tight but, for aerodynamic pressure measurement, a microscopic leak will not change the pressure reading much if at all.