Re: Exposed gears/chain
 

I can tell my co-workers all day long to not be an idiot, but that won't prevent them from being tired, or sleepy, or hurried, or stressed, or distracted, or uncoordinated... in general, careless and prone to mistakes.

I can however engineer out risks whenever I'm able to; otherwise I'll put barriers and guarding in between the identified risks and my coworkers; when I find that isn't enough I will require specific safety equipment and procedures in order to keep them safe.

Re: Exposed gears/chain
 

QFT.

Re: Exposed gears/chain
 

I panicked for a few moments trying to think of how we could quickly fashion a guard - we didn't bring enough spare aluminum, and I was starting to figure out how I was going to quickly cut and bend a U-shaped bracket out of Lexan... then we found an extra piece of coroplast we were using to mount our team number, folded that into the appropriate shape, added some self-tapping screws and voila! Problem solved.

For the drive gearbox cover plates we did cut some Lexan so we could still see what was going on down there.

Re: Exposed gears/chain
 

I do not understand why there are more restrictive requirements at some regionals. Not able to compete because an inspector requires a chain guard?? How can this happen? I can understand a guard being required if a failure could cause parts of the robot to fly off the field but not a chain. No one should be touching the robot while it is running on the field.

Re: Exposed gears/chain
 

Is the chain anywhere near an area your hand might be while carrying your robot off the field? Is that chain attached to a mechanism with a lot of leverage, and can it move while the robot is disabled?

Re: Exposed gears/chain
 

Andy,
I have to trust my inspection staff at events. If they ask that you cover a pinch point, it is likely that they are evaluating that individual robot based on past experience. I have seen things that would turn your hair grey and fall out. (Have you seen my picture?) As for some of the others, how many of you using chains can operate the mechanism without power? Can gravity cause it to move even if it hasn't ever done that? Can another person bump into your robot in the queue or on the floor and cause that mechanism to move? If you answered yes to any of these, someone is going to have a hand near or in your robot at some point.

Re: Exposed gears/chain
 

All it takes is one mistake... You don't regrow fingers. Perhaps it's too far in the past for many to remember, but there was a widely talked about incident in 2008. I can't find the thread dedicated to it (I'm pretty sure there was one), But it's discussed here: http://www.chiefdelphi.com/forums/sh...&postcount=125

The end result was that someone (I believe it was a college aged mentor) lost part of his finger when it got caught between a chain and sprocket.

You can't just evaluate safety based on likelihood of someone being an idiot. It's a combination of likelihood, random mistakes, and severity of the result. Losing part of your finger is a very severe result, and we try to treat it as such when asking people to put guards on their robot.

Re: Exposed gears/chain
 

I'm all for guards, build them all the time. But proper hand saftey must still be taught and enforced at all times.

Probably 80% of belt and chain injuries I've seen in industry have been during service or troubleshooting with the guards removed.

Safety is a three part process, proper personal training, physical safeties/PPE and proper leadership.

Re: Exposed gears/chain
 

I remember being a student on an FRC team and guards were always on our mind during the design process, after going to several regionals in past years and having to add them on.

Now I do agree that guards for chain and gears are not being mandated like when I was on the team. But now that I am a mentor for 5+ years I have found that this should be the mentors job not the RI. There is a way to design things safely and keeping that as a goal is important for design intent. The kids don't know how to design things safely yet, they are still learning, that is where mentors step in to teach and show them how to do it, and then let the kids spend time in CAD making it safe. There are many ways to make a safety guard advantageous in your systems. If you are using belts or chain you can use a guard to help increase your tooth wrap or to auto tension your system.

In the end if the bot is unsafe and someone gets hurt it is on the mentors.