paenian

With the cheap steppers I used... not very big. The big gear actually failed, although after about two years, so not terrible. I'm replacing it with a beefier stepper motor, one the the Nema 17s that are pretty standard on 3D printers these days. Steppers come crazy big, so I don't think there's much practical limit on scale - after a while you'd need to support both sides of the axle, but hey.

The printed parts are all PETG, and not even carbon fiber reinforced - but they're still plenty strong enough for the torque needed. The trick is to make them thicker - check out Gear Down for What if you want to see some truly insane torque from printed parts:Now, if you look closely, I did not 3D print any sprockets - because the sprocket tooth needs to be thin to fit inside the chain, and therefore can't be thick enough to handle the torque. So I bought some metal ones off of Amazon.

Heat is a good indicator of inefficiency - and in the case of compressing air you generate a ton of heat. The copper pipe is there because it got hot enough to melt the polypropylene one :-(. Most air compressors can't operate steady state without melting! Pneumatics are a great way to transfer power and make powerful but lightweight tools, but it's certainly not the most efficient use of power

I made it 24hour so that I could attach notes to it - maybe paint night and day scenes on the hour gear.