3D Printing Bolt Parts From the Open Dynamic Robot Initiative

So just eight-days shy of six-months later I finally get around to writing another post. I have ordered most of the components to build a single leg of the Bolt, from the Open Dynamic Robot Initiative. Luckily I opted to get my own 3D printer versus using 3D Systems on-demand service: as the Open Dynamic Robot Initiative has increased the upper and lower leg lengths to reduce the frequency in the system. I also decided to purchase the encoders that do not require lathe modification, which seems to have been a good decision as folks are having issues with the modification. Anyways, on to my printing decision.

I decided to purchase an Original Prusa MK3S 3D printer kit and build it myself, $749 plus shipping. The build took a full day, close to 10 hours, but it was fun. I have printed the transmission_pulley_at3_t30_center.STL and upper_leg_structure_base_200mm.STL in SLA.

Transmission Pulley

It appears that it may be difficult to push the center pulley through the transmission pulley, I have ordered and arbor press to test. I am going to test print in a few other materials, but the SLA seems to mesh with the timing belts well.

Actuator Shell Top View
Actuator Shell Bottom View

The printed support structures left a little to be desired as far as surface finish. This was a 24 hour print at 0.05mm ULTRADETAIL. I am going to purchase the multi-material head and see if I can get a better finish. But it takes what is an $83 dollar component and reduces the per-part cost to an estimated $1.24.