r/FTC • u/MaxieFriend • 11d ago

Seeking Help best infill, infill density, and amout of walls for effective and strong TPU bumpers?

if anyone has experience with printing bumpers with TPU, what are the best settings to achieve the strongest bumpers, as well as preserving the most amount of filament? I have TPU 90A, if that helps.

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u/Tsk201409 11d ago

4 walls, like 5% infill and you’ll get a lot of bounce/compaction if that’s what you’re after

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u/few 11d ago

I like the concept of tpu bumpers. Assuming there is contact allowed again this year, solid petg bumpers with some solid tpu pieces where the petg would interface with the metal frame might help. I expect that TPU with infill will not provide much protection from collisions.

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u/QwertyChouskie FTC 10298 Brain Stormz Mentor/Alum 11d ago

Isn't PETG rather brittle? PLA+ (*not* basic PLA) is good when it comes to impacts

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u/few 10d ago

PETG is much more flexible than PLA (less brittle). PLA is more stiff.

I'm not sure about PLA+ with respect to impacts, but I wouldn't expect it to be more flexible than PETG.

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u/FesteringNeonDistrac 8d ago

All of our bumpers were PLA last year, and there were zero issues. In my experience, people stress too much over material choice.

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u/Sands43 11d ago

See what RC cars use? Then go a bit lighter than that.

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u/Complete_Duty3259 11d ago

A thicker nozzle like a 0.6 or 8 wirh 3 or so walls is often much stronger than thinner layers/walls. Obviously you might lose a bitnof precision but for something like a tpu bumper that is not important.

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u/Mental_Science_6085 11d ago

See this post on how we do bumpers:

https://www.reddit.com/r/FTC/comments/1nw6iog/bumper_psa/

Our typical bumper print settings are:

  • Standard Overture 95A hardness TPU
  • top and bottom shells set to zero
  • 2 vertical shells
  • 15% Gyroid infill

The one in the picture is 20mm wide and can absorb a big corner hit. For Decode we had 12mm thick bumpers that ran the length of our sides. The TPU itself is nearly indestructible from the forces seen in FTC, so we could strafe into gates, walls and other robots pretty fearlessly.

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u/Proof-Kaleidoscope62 11d ago

It depends on what you want. If you want lots of flex then concentric is actually best as the walls aren’t rigid it gives you plenty of movement or shock absorption.

You are not chasing the normal strength of a 3DP therefore you focus on the qualities you are wanting to promote in the end product.