Monday, February 1, 2021

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.

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