Powerful, accurate, compact and cheap actuators are like unicorns. They do not exist. However, this is exactly what the [3DprintedLife] robot camera arm needs, so he developed a customized 3D printed high-torque strain wave gearbox powered by a cheap NEMA23 stepper motor.

Strain wave gears, also called harmonic drives, are not uncommon on Hackaday. It works by deforming a flexible toothed spline with a rotating elliptical portion that meshes with the internal teeth of the external spline. The external spline has more teeth, which makes the internal spline rotate slowly compared with the input, thereby achieving a very high gear ratio. Generally, a flexible spline is quite long to allow it to bend at one end while still having a rigid mounting surface at the other end. [3DprintedLife] solves this problem by creating a separate rigid output spline, which also meshes with the flexible spline.

At first, he used a toothed rubber belt for the flexible spline, which proved to be a bit too flexible and introduced unnecessary clearance. It is replaced by a 3D printed flexible spline, which also allows [3DprintedLife] to adjust the tooth profile to achieve maximum torque handling and minimum backlash. He also created an automated test bench with a 20 kg load cell, Arduino and aluminum extrusions. This allows repeated testing of each design iteration without human intervention, thereby quickly identifying and repairing design weaknesses when parts are damaged. The final version can repeatedly produce 10 Nm of output torque, and [3DprintedLife] can only break it by putting almost the entire body's weight on the output arm.

All parts are printed with PLA, but [3DprintedLife] plans to transfer to nylon in the future. The robotic arm is still in the design stage, but we look forward to seeing it B-roll for future video collections.

The camera arm does not need to be powered to work properly. [Ivan Miranda] and [Alexandre Chappel] recently built a large camera arm for their studio, and both used a lot of 3D printed parts.

Nice building. What printer/plastic are you using?

Are you even reading or watching?

[P] Re-depleted [L]-Isostatic Uranium [A] Acetate

He mentions PLA in all prints, but plans to use nylon in the future.

According to my experience, PET-G is also a good choice.

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