Abrasive

Hey that sounds like a great idea!

Any way I could donate polycarbonate part(s) for this testing? I'm really interested in how the different materials compare. As far as Onyx printing I have heard through the combat robot community that Endbots is quite reasonable for commissioned Onyx prints.

What is the Izod impact strength of Xstrand and what is its specific gravity/density?

I wanted to take existing parts I had an make a mold for them to make them from PCL. I decided to try Cura's experimental mold feature, but it seems completely backwards to me. When I think of a one part mold I think of it like a bath tub where you'd fill it from the top and let it cure. Cura seems to force it to be an upside-down bathtub no matter what so the only way it could be useful is if you use supports. Removing the supports would cause the mold to be quite rough, unless you use PVA. Mandatory use of PVA seems over complicated and expensive though. Am I using this feature incorrectly? If not is there a way I can invert the whole mold? I can't just rotate it 180 degrees because then it reslices putting a new ceiling on top.

Is there any impact strength test data for this material? The data sheet doesn't appear to have that data.

I used polycarbonate for a weapon adapter for the combat robot and it held up. The weapon blade screws into the bottom of the adapter and the brushless outrunner presses into the top. CAD models shown in the attached pictures. I could't use flexible filament as it needs a fair amount of rigidity. I was skeptical that it would work as it is spinning at a few thousand RPM. I thought the screws would split it under the torque during impact, or it would just explode. The adapter I made is on Cubey's Revenge, the taller tube robot with big blue wheels. This is one of the more violent fights and it didn't break. I'm going to iterate on the adapter some more and experiment with 3D printed wheels that can hopefully survive horizontal spinners. Flexible filament might work well for the wheels, I just need to keep them under 14g or so.

That's a cool chart! I guess looking at the chart I would expect the transparent PC to be better for a combat robot but in reality it is significantly worse. I guess I would need to look at an impact strength graph to be able to visually gather that info?

Interesting, according to the TDS the mechanical properties of the transparent is at least slightly higher in every category except impact strength, which it is much less: 4.1 kJ/m² (t) vs. 14.9 kJ/m² (b/w)

Thanks Torgeir, That's the most long-winded and informative post I was never expecting that also lead to one single direct question? In my case I was using all Ultimaker polycarbonate filaments in the varieties of clear, black and white. I would just print the part and attempt to break it with a hammer after it had cooled to room temperature. There was no time for UV radiation to have an effect. No chemicals touched them other than skin oil. I'm building a combat robot so this was a litmus test for "can this take a forceful hit?".

I'm curious as to why the clear polycarbonate is so brittle compared to the black and white? I print the same part with 90% infill, all Cura settings the same, and then hit it with a hammer to test the durability. The clear PC immediately catastrophically fails and explodes into a ton of pieces. The black and white I can hit 30+ times and it won't break. I'm not sure if this is a material issue or if the clear should have its own temp profiles because it has different needs? That being said I really love this material as it prints so consistently well on my UM3 and is super strong. For the time being I've just been using the clear to test fit and weight and then print the real part in black or white.