RS550 Enough Power?

[Kit Gerhart]

Originally Posted by Alienvin

So Jim,

I'm looking at the RS-550, 19300 RPM Free Speed with a Banebots Gearbox with a Gear Ratio of 256:1, then maybe a 10T off the Banebot Gearbox to either a 48T, 54T, or 60T Sprocket attached to a 3' Arm Extension that at the end of it has a 1'6" arm extension that to has a gearbox setup on the end of it. All in all I would like to keep the entire weight to the arm under 7lbs.... What you think?

Be very careful in how you use a 256:1 Banebots. They are very easy to destroy. Even with a 550 motor, you get LOTS OF TORQUE at the output, not to mention what you get with a 775 or Fisher Price motor.

[Ian Curtis]

For more anecdotal 256:1, we used them for this actuation. There were two of them (one powered the "stick" that pushes it up, the 2nd rotated it forward to lock it out. One of them was cantilevered, the other was not. The cantilevered one failed at 6:30 PM on Thursday, so we luckily got a chance to fix it without any intervening matches. We un-cantilevered the output, and it did not fail for the rest of the tournament. We never needed to replace the one which was not cantilevered to begin with. There were probably 50 cycles on the one we replaced, and 100+ on the one that was not replaced.

There was *a lot* of torque in that set up. We wouldn't do it again (apparently our lead mentors were betting in the stands on whether it would fail every single lift), but the BB did hold up. We must've used the 550 and 540, because both FPs were in the toughbox on top of the arm.

Just another data point.

[Kit Gerhart]

Originally Posted by iCurtis

For more anecdotal 256:1, we used them for this actuation. There were two of them (one powered the "stick" that pushes it up, the 2nd rotated it forward to lock it out. One of them was cantilevered, the other was not. The cantilevered one failed at 6:30 PM on Thursday, so we luckily got a chance to fix it without any intervening matches. We un-cantilevered the output, and it did not fail for the rest of the tournament. We never needed to replace the one which was not cantilevered to begin with. There were probably 50 cycles on the one we replaced, and 100+ on the one that was not replaced.

There was *a lot* of torque in that set up. We wouldn't do it again (apparently our lead mentors were betting in the stands on whether it would fail every single lift), but the BB did hold up. We must've used the 550 and 540, because both FPs were in the toughbox on top of the arm.

Just another data point.

We tried using one with a Fisher-Price for our arm rotation in 2007, and destroyed it instantly. In retrospect, we should have known better, given all the power of the F/P and moment of inertia of the arm.

If used properly, and with less powerful motors than the F/P, the 256:1 planetaries are fine. Also, I think the current ones are stronger than the ones we broke in '07.