Chain guard rules?

[TheHolyHades1]

We have an entire length (about 8" c-c) of chain exposed on the side of our collector. Should we look to manufacture a chain guard of some sort? In our testing, the ball was undamaged by the chain even after repeated and direct contact, which seems to satisfy the only thing I can find regarding this in the rules:

R8. Protrusions from the ROBOT and exposed surfaces on the ROBOT shall not pose hazards to the
ARENA elements (including the BOULDERS) or people.

Is this something that is usually handled on a case by case basis, or is there some sort of blanket rule that applies here that I don't see?

[nickbrickmaster]

Just make sure it's safe. I would also consider the possibility of the chain getting stuck in another robot.

[cgmv123]

It's handled on case-by-case basis and unfortunately seems to depend on the inspector. If you post some pictures, we can try to give you an idea of what to expect at inspection and/or give you ideas on shielding.

[EricH]

I would shield it.

When you're testing in the pit, is there the possibility that someone isn't paying attention and puts a body part onto the chain while it's moving? (Hint: That's not actually a question.)

That being said, depending on the implementation, it might not need guarding.

Personally, not officially, I'd be thinking of lightweight guarding for it; officially I'd have to actually see it to determine.

[rich2202]

The issue is how "exposed" it is to people. If it is exposed on the side of your robot, then it needs to be covered. If it is burred inside your robot, and only the ball can easily get near it, then it is less of a problem.

[Jon Stratis]

ROBOT parts shall not be made from hazardous materials, be unsafe, cause an unsafe condition, or interfere with the operation of other ROBOTS.

The concern here with chain is that it can literally detach body parts that get stuck between the chain and sprocket! And yes, this has happened at an event before. (I think there's more info in another thread somewhere, but I couldn't find it).

So, your inspector is going to try to evaluate the risk, and probably land on the side of Safety. If it's exposed, put a shield on it so you can't get a finger stuck between the chain and sprocket, at least not without really trying to.

[Jimmy Nichols]

Originally Posted by Jon Stratis

The concern here with chain is that it can literally detach body parts that get stuck between the chain and sprocket! And yes, this has happened at an event before. (I think there's more info in another thread somewhere, but I couldn't find it).

So, your inspector is going to try to evaluate the risk, and probably land on the side of Safety. If it's exposed, put a shield on it so you can't get a finger stuck between the chain and sprocket, at least not without really trying to.

I believe a similar incident happened at the Pittsburgh regional a number of years ago. When in Doubt, Guard It.

[MrForbes]

You need to guard the area where the chain meets the sprocket. The chain itself isn't very dangerous, but if a finger gets near where the chain goes onto the sprocket, bad things can happen. A flat plate of polycarbonate (ie. Lexan) over the side of the sprocket, extending about an inch past the edge of the sprocket, and mounted as close to the chain as you can get it, should suffice.

[FrankJ]

Originally Posted by TheHolyHades1

Is this something that is usually handled on a case by case basis, or is there some sort of blanket rule that applies here that I don't see?

Rule 9 is the one that covers guarding. As you see it doesn't give a lot of guidance. As others have said, it is not really the chain but the nip point where the chain meets the sprocket.

R9 ROBOT parts shall not be made from hazardous materials, be unsafe, cause an unsafe condition,
or interfere with the operation of other ROBOTS.

[jvriezen]

Whether or not a guard is used (sounds like it should be) I would also consider a sticker like this: http://www.sitewaredirect.com.au/saf...0-x-180mm.html for the times where the guard is removed for service/tightening/tuning, etc.

Consider the scenario where the someone stumbles on some tool on the floor of the pit, and uses their hand against the robot to stop from falling, just as the robot is enabled (with a software bug that causes the chain to move without input) or just as someone is activating the controller to test the component. I've seen close calls that match this scenario with unguarded elements.

Also, don't take the advice here to mean: "We better get a guard on this before bagging so that we don't have trouble with the inspector" Take it to mean: we better get a guard on this ASAP, because there is a real risk any time we hit the bot's main power switch.

As an inspector, I often tell my teams of sharp corners/edges that won't pass inspection, but all too often I have to follow up with the fact that it needs to be addressed nearly immediately because I don't want any more hand scrapes/cuts for me or others on the team during build season.