This is a ABS/TPU printed suction cup that can be done with a single extruder by pausing and switching filament. The suction cup can be used on the end of a robot arm for Picking and Placing stuff. This design is meant to be a general example/starting point. No hookups are provided for a particular vacuum source. Add what you need or your own setup.
Things that worked well:
- Bellows walls are 0.4mm thick, any more and the cup is too ridged.
- No more than 45 degree angle.
- 6mm long on the "Increasing Diameter" half of the bellow is about as long as you want, and even at that length the upper part start to bend inward a bit due to plastic contracting. The decreasing diameter section of the bellow prints just fine.
- Sticking with .1mm layer height on the bellows worked out better than 0.2
- Upped the TPU temp to 230 for better layer adhesion.
- You want more (AKA thicker) material on the inside of the cup lip. This provides a spring force to pull the lip back over center and prevent it from folding upward. (See video)
- I sliced it twice, once for ABS and once or TPU, then manually spliced the Gcode together. Beware using different layer heights. If you transition from 0.2 to 0.1 you might miss 0.1mm of the transition layer, if your not careful. ALSO NOTE: add extra extrusion (about 14mm for my bownden tube length of 20") to make sure enough pressure is immediately applied to the TPU to ensure a nice thick, well extruded first TPU layer. Else you will get a heavily underextruded first layer, and the cup will leak, and maybe break at that layer.
- Fan/Enclosure usage didn't seem to matter much at all to the TPU. (Enclosure good for ABS obviously)
I have found the TPU to be extremely tough, and always goes back to the printed shape. This same accordion design could be used a vibration isolation device.
ABS to TPU layer bonding has been good.
A test cup has been in the dishwasher for 3 weeks with no ill effects.
I had issues printing smaller diameter cups. I believe that was due to heat buildup and printing multiple cups at once should solve that issue.
Please post your makes/modifications to this design.