Flexible for air brake seals?

I’ve printed a couple of replacement seals for use in brake valves for the local railroad museum. Does anyone have experience to share on how the resin stands up to 90 psi air with oil thrown in? Thanks!

@Paul_Hollingshead Generally my outlook has aways been that 3D Printed replacement parts shouldn’t be used in situations where failure can result in death, dismemberment, decapitation, or injury.

So fixing the AC mixing flap on my Saab 93 with a printed part, Yes. Fixing the breaks on my Saab 93 with a printed part, No.

I’ll let you draw your own conclusion from that.


I agree - not on my car. But George Westinghouse, in 1868, invented a fail-safe system. If a seal goes, then the brakes apply. Integrity of the air system is specifically checked each morning that the trains run by the engineer and brakemen.

We have used a print for mechanical purposes that has air and a stud flying through the system the stud usually breaks our print but that is physical contact not fluid like the air. Plus we only use about 30-35 psi. I would share Michael’s theory on this though test before you go replacing things, especially if someone could get hurt as the end result which no one wants to see. Good luck

I’ve just begun using flexible to test some prototype parts. While it is quite flexible, it has a very low ‘stretch’. As such, flex angle is directly related to thickness. The thicker the piece, the less angle the part can be bent. At failure it ‘cleaves’ and leaves a shiny surface at the break like you would expect from acrylic. My ‘highly technical’ analysis of the material is that it is similar in consistency and feel to a stale gummy bear.