Team 449 Climber

[Kevin Sevcik]

Originally Posted by ollien

Far from impossible. Just add some 2" sticks extending straight up (or whatever direction you're climbing).

Nothing's impossible or even very difficult at this stage. It gets tough when you show up at your first competition with a climber at the very top of your robot volume, though. I think there's a lot of people forgetting that the challenge isn't climbing, it's pressing the touchpad for >1s.

[jojoguy10]

How much weight was that in the video? Looks like a cool design! (At least, it's not velcro anyway )

[qscgy]

Originally Posted by jojoguy10

How much weight was that in the video? Looks like a cool design! (At least, it's not velcro anyway )

It probably weighed about 40 pounds, although we designed it to lift 150. It's the frame (made of 80/20) from our 2010 robot, with a battery and electronics board attached.

[jojoguy10]

Originally Posted by qscgy

It probably weighed about 40 pounds, although we designed it to lift 150. It's the frame (made of 80/20) from our 2010 robot, with a battery and electronics board attached.

I'd be very interested to know how it performs at about 150lbs (maximum robot weight is 154lbs)

[Oblarg]

Originally Posted by jojoguy10

I'd be very interested to know how it performs at about 150lbs (maximum robot weight is 154lbs)

The gearing was selected very conservatively to ensure that we're on the rising side of the power output curve.

The current gearbox is 50:1. Mini-CIM output torque is listed at 1.4 N*m. Our winch drum is 1.25'' diameter, so .625'' radius.

Neglecting friction, we have:

(150 lbs * .625'')/(1.4 N*m * 50) = ~15% of stall torque.

Now, I have really no idea how big the frictional losses actually are in this system, but I don't think there's any way they'll take us from 15% motor loading to over 50% (which is peak power, i.e. the loading for which this gearing provides optimal climb rate).

Fully-loaded climb rate (using the frictionless numbers) is somewhere around 6'' per second.

Upon reflection, we could probably gear it a bit faster (we had done the math for the gearbox when we were considering a larger-diameter winch).

[T^2]

Your gearbox will fail you after a regional's worth of matches, maybe sooner. The aluminum ring gear will flex enough to allow the planet gears to ratchet, and you will lose the climb.

[Oblarg]

Originally Posted by T^2

Your gearbox will fail you after a regional's worth of matches, maybe sooner. The aluminum ring gear will flex enough to allow the planet gears to ratchet, and you will lose the climb.

Are you sure? The 50:1/mini-CIM combo is labeled as acceptable by VexPro's documentation, and as noted above we're not actually anywhere near the peak loading on it.

[T^2]

Originally Posted by Oblarg

Are you sure? The 50:1/mini-CIM combo is labeled as acceptable by VexPro's documentation, and as noted above we're not actually anywhere near the peak loading on it.

Catapult failure in first 2014 regional, canburglar failure in second 2015 regional. Similar physical setups.

[Oblarg]

Originally Posted by T^2

Catapult failure in first 2014 regional, canburglar failure in second 2015 regional. Similar physical setups.

Any gearbox suggestions, then?

[T^2]

Maybe custom if you have resources. Vexpro CIM gearboxes would work, but bulky because you'd need two reductions.

[Oblarg]

Originally Posted by T^2

Maybe custom if you have resources. Vexpro CIM gearboxes would work, but bulky because you'd need two reductions.

We don't have much in the way of machining resources at all (miter saw, drill press, and a little hobby lathe), and the drive gearboxes would be an absolute nightmare in terms of space/weight.

I think I'd rather try to add a 2:1 reduction or similar via. chain to reduce torque on the gearbox if this proves to be problematic.

[Ari423]

Originally Posted by T^2

Catapult failure in first 2014 regional, canburglar failure in second 2015 regional. Similar physical setups.

Are you sure you were using the VersaPlanetaries correctly? I've used them a number of times without problems and I've pretty much only heard good things about them. Were you properly greasing them? Did you check the max loading guide before choosing a reduction? Did you assemble them in highest to lowest reduction order? Did you support the end of the shaft?

[SuperBK]

Wait - there is a knot in the at the bottom end of the rope? Or, Are you planning to bring your own rope and its legal to have a knot at the bottom to grab onto?

[Oblarg]

Originally Posted by SuperBK

Wait - there is a knot in the at the bottom end of the rope? Or, Are you planning to bring your own rope and its legal to have a knot at the bottom to grab onto?

https://firstfrc.blob.core.windows.n...ligibility.pdf

[Kevin Thorp]

Thanks for posting your design.

If there is any concern about Versaplanetarys taking the load, you could go with half the gear reduction and a 1:2 chain sprocket ratio.