Quote:
Originally Posted by asid61
Depends on the pulley diameter. We used a 1.06" diameter pulley with 2 RS-775s at a 21:1 reduction to get optimal speed on 6 totes, and that with a very long lever arm adding friction. 254's lift on slightly smaller pulleys was 2 775s on ~12.5:1 reduction and was very fast, due to the much lower friction/ smaller lever arm.
A single 775 going to a similar pulley would only need maybe a 50:1 reduction even with a long lever arm. If you place it nicely you could get away with a 25:1 or 30:1 reduction.
You said you are using servos to hold the totes; why not just use the arm? FRC-legal servos are very weak.
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So I'm using a 1:100 reduction, and the elevator runs on roller chain with 16T sprocket ends. I recalculated with a 1" diameter, and it looks like this thing is going to be much slower than expected. But then again, I imagined the strategy of this would be to have this for other bots while the tethered main bot works on the landfill, assuming weight limit allows for this and the main bot.
Really, the servos are just to keep the first tote from sliding too far out. Also, the servos are MG-995s and a stress test video on YouTube showed that they are decently strong for this purpose... on the other hand I'm not sure if those servos are FRC legal, is there a list somewhere of what is legal and what's not?