This is a deprecated version. New version available here:
Flexible Landing Gear for Quadcopter "Crossfire" Version 2
Since the feet of my quadcopter "Crossfire" by MikeyB broke off during my very first test flight, I created these convenient, robust and flexible landing gears (you can drop the copter from about 30cm height with no problems, maybe even higher but I didn't test it higher).
These landing gears aren't attached to the arms but to the bottom plate using the two screws which are already there. They also have hexagonal holders for the nuts to conveniently retighten the screws between flights.
With 30% infill (recommended) this adds about 50 grams to your weight.
Note: Depending on your screw length, nut size and print settings, you might want to fine-tune the nut holder. Make sure that the nut fits tight but doesn't break the layers apart when being screwed tightly.
When using different screws than M4 you have to change the size of the nut holder. The screw hole takes M3..M5.
Print only one thing at once until you tested if it is good or should be fine-tuned.
Print in 0.2-0.3mm layer height with 30-50% infill and 1 or 2 extra shells (= 2 or 3 diameters). No raft/support required if your printer can handle 45 degrees of overhang, which pretty much all do.
When playing with these parameters, make sure the part where the nuts are placed is rigid enough, it will be the most fragile part of this thing.
Using skeinforge, I used 0.2mm layer height, factor 1.8 width over height, 35% infill with 2 extra shells and 3 solid layers while printing at speed 60 maximum (at least in the layers with the nut holder).
Screw the top plate, arms, bottom plate and these landing gears with screws (M3..M5, model designed for M4, metal recommended) and put a nut (nylon recommended) in the nut holder. You can tighten the screw without holding the nut as it will be held automatically in place.
The screw can be very tight. It might crack, but this is not critical. I did some extreme tests over-tightening the screw as much as I could; the layers broke apart on the outside but it still held together between the two screws without any problem.