White Paper Discuss: Nothing But Dewalts

[Joe Johnson]

Originally Posted by jimfortytwo

Thanks Ryan. I was responding to Max's suggestion that retaining all three reduction stages (not what Joe P recommends) might lead to a gearbox failure. Personally, I think that the XRP can probably handle twice its rated torque-- but thats just a gut feeling.

Although I am aware that the CIM outputs only .79Nm at 40A, it must be remembered that our 40A breakers can actually sustain upwards of 80A for short durations. Using the 40A number, even with all three stages we remain well under rated torque for the transmission. In my calculation I used the stall current to be conservative. I am curious what the real maximum momentary load from a CIM motor is, once you factor in our breakers and our non-ideal voltage source.

I too am confident the Dewalts can take 2X the published numbers.

As to the 40A fuse letting much more than 40A through for short periods, this is a certaintly. "Short periods" are essentially infinite time for the gear teeth in that once they are broken, they are broken. Beyond this, there is the problem of static vs. dynamic loading.

BUT... ...I really question the need for a 47:1 ratio with the Chiaphua motor. 47:1 with 3 planetary stages will provide effectively 34:1 which would give you 70+ N-m With a 12mm (.5") radius sprocket you'd get 6000N (1400 lbs). That is a lot of force!

Beyond this, the sprocket woud be turning at a mere 2 Rev/Sec. Not very speedy.