Hi Guys!
For some reason I can't post through my own account, so I'm posting through my friend's.
My name is Somer Kwon and I am a hardware member of Team 5700, the SOTA Cyberdragons. During this year’s off-season we wanted to expand our knowledge of robotics. We decided to break into 3 groups and begin growing our knowledge in 3 areas:: gear boxes, chain and sprocket, and flywheel and other shooters. My group is working on learning the applications of chain and sprockets.
As a proof of concept, my team plans to build an 18” arm that can lift a 5 lb weight at the end at a controllable speed We would like to use a sprocket and chain system from a gearbox to actuate the arm. We’re looking at 971’s 2016 intake CAD as an example.
The basic power and shop tools we have access to include: a lathe and mill (w/o DRO), a vertical bandsaw, chopsaw, bench grinder, and maybe a water jet (at TechShop).
So far, we have decided to use a RS775 18V motor through a 180:1 reduction. This would provide plenty of torque and a 1 rps angular velocity, which seems to be slow enough, at 20 amps. This reduction seems really huge and we’re not sure if we did the correct calculations. Also, how would we be able to maintain a 20 A current? Since motor controllers control motor speed by changing average voltage with PWM, is it possible to change the input voltage to reduce the speed of the arm and maintain enough torque, therefore reducing the needed reduction?
On the mechanical side of things, we need help with choosing what sprockets, gear boxes, and chain we should use for this project. How do you choose between 25 and 35 chain? What are the best products to use, and where should we purchase this hardware. Tensioning, adjusting chain length, sprocket mounting, greasing, chain and gearbox efficiency, etc., are all new concepts we have little experience with. If you have any tips, resources, videos, or comments about how to work with and think about chain and sprockets, that would be extremely helpful for us.
Thank you for your help!
Somer Kwon
Mech En | SOTA Cyberdragons Robotics, Team 5700
sotacyberdragons@gmail.com