pic: gear boxes
 

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Congratulations. A kit gearbox finally broke due to team efforts. How much force/how many hits did the breaker(s) use? And, more importantly, is it still usable?

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That looks like somthing i would do. why are you guys being like me, its not good for you.

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The kid was not hitting it very hard and it only took a few hits. And yes it is still usable because we use it like that in the Ramp Riot.

Re: pic: gear boxes
 

Well, I guess not not hard. I didn't personally see it happen, but boy did my jaw drop when I saw it. I know casting's are brittle, but that seems a little much. The gear box is completely useable, unless something else goes. Either way, we have two more of these if we have to replace it. Our mentor didn't completely trust these boxes, so bought spares. Guess he knew something!

So kids, remember: listen to your mentors, they might possibly not be totally wrong...

Re: pic: gear boxes
 

Funny, I thought it only happened to us.

The same exact thing happened to us on our practice robot. It still worked when it was broken but we got it welded and although it doesn't look great it works fine. I ll try to post a picture.

Dave

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When I first saw the picture I thought it was intentional to reduce weight. I had no clue that the casing was that brittle, that is very surprising.

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Gotta wonder why exactly you'd be smacking the gearbox with a hammer...

at least get a mallet.

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alignment....obviously....or perhaps they we trying to pressfit something to the top of the gearbox :)

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If I wanted to align it by smacking it with a hammer, I'd at least hit the aluminum base plate, instead of the casting.

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all I have to say is wow...just goes to show that you need to watch all your hammers

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Well I guess you figured out that the gearbox casting wasn't designed to take a hammer hit on the side walls. Those side walls were designed as thin as could be cast in order to keep the weight down. Under normal robot operating loads, that should never happen .......

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We had an unexplained fracture exactly like this which we ascribed to manufacturing fluke. We were just playing with the practice bot and some observant student noticed it had developed a fissure. This was less than an hour of use...

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as long as it dosent happen in the middle of a match :)

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Nope sorry. I'd say that's the wrong mentality. (well, maybe not wrong but less than optimal) I's say we should all be striving to build robots that don't break at all. :)

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Well, yeah, you're completely right. Something we should all take away from this then...: Never underestimate the um...ability.... of students in small groups.

Though I act like it's not my fault. The knowing are to blame when someone makes a mistake unknowingly.

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I have to say...if those boxes are that weak...might be good to avoid them entirely. if they randomly break after little use I wonder if FIRST would replace them for you?

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Well, thing is, they don't break randomly. Castings are generally brittle, and a hard strike will crack them. We have spares, and it's not affecting operation.

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...or it might be good to avoid doing stupid things like smashing a thin metal casing with a steel hammer...

Just a thought...