This is my design for a quadruped. Most 3 Degrees of Freedom (DoF) legs also have 3 parts to the legs. I wanted to see if it was possible to get 2 DoF from one joint.
- I then decided to go with a cable drive and keep the servo's inside the body, rather than make them part of the leg as most others have.
- Make it modular so that you can attach what ever size servo's you want, to it. I have not included the central square into the downloadable files as this would depend on the size of servos you choose to use as well as what and where you would like to mount any electronics and/or sensors or cameras you want to include.
- The two part leg should print pre-assembled. There is 0.2mm gap so even a normal self build 3D printer should be able to print this. I sliced this with KISSlicer64 but be sure to enable "Avoid Crossing Perimeters" in your slicing program. I found that Slic3r does not slice this thing right and screws up the design. Let me know if you have better luck.
The first part of the leg is just over 120mm long and the second part is about half that, so it should just fit onto a 200mm x 200mm heatbed with a couple of mm to spare or you could rotate it 45 degrees if it's to close.
I would love to hear feedback if anyone finds any bugs or if you have any bright ideas.
The idea with this was to get all the servos in the body and use cables to articulate the legs, You'll notice little "notches" just before the hinge on the long part of the leg. You should push a 1mm diameter bar through these holes to allow the cable to then tie onto that. The cable should then be thread through the in line notch on the upper leg. Fishing line should work great (The non stretch variety).
Similar notches are near the ball joint. 4 of them with 1 servo driving the opposite sides of the legs. Again these cables should be fed through the guides on the hip. The extra two guides on the hip are for the cables going to the lower leg.