Nightmare Repairs At Competition

[EricVanWyk]

Originally Posted by George1902

http://www.theroboshow.net/

It's the first story in Episode 2.

Thanks!

[Lil' Lavery]

Originally Posted by coalhot

I remember this, walking around the pits in Philly 2008 and seeing the arm split in half. If I recall, you guys got it completely replaced with the spare in time to have a fully functional robot in the first quarterfinals match. It was quite impressive.

We didn't hurdle in the first quarter-final match, as we weren't confident in our repair yet. We did participate in the match, run laps, and lock an opposing track ball in the corner for as long as possible. We managed to get a bit of testing between QF1-1 and QF1-2, and were back in full force in the second quarterfinal. Not that it mattered much against the 103+272+834 combo. They summarily trounced us.

[AdamHeard]

Originally Posted by Chris is me

So I just got back from the WPI Regional and I've got a story to tell. As I was preparing this thread, I saw 237's awesome transmission repair and knew there had to be a ton more of these kinds of clever, dirty repairs in FIRST. So I thought I'd wrap our little story into a general thread so that the whole CD community can hear about different teams' ingenuity under pressure.

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So in our last qualifying match, after we had secured the number 1 seed, we went to hang for 10 and then suddenly our arm snapped all the way back. We had sheared a 20 tooth pinion on the arm. We swapped for our spare so we'd be ready for the first quarterfinal, and what do you know, it happens again. Perhaps we should have decided not to hang, but since the gear lasted through a regional and a half we thought we were safe...

At this point, panic starts to set in. We were out of 20 tooth gears, so a lot of the team thought we were done. Out of utter desperation, a few students and I dig through the pits trying to find ANYTHING that works. We ask any team we can find if they even used Vex gears. No dice. We dig through our own supply just trying to find anything that can work.

One of our mechanical students finds the 19 tooth, 3/8 Hex drivetrain gears, hands them to me, and asks if they will work. We have to try. I sprint the gears down to the machine shop for secondary operations while I tell another student to let the drive team and repair crew know that a spare is on the way. I run it down the street to the machine shop (it's in another building) and then ask if they can broach it. They say yes, if they can get a hex broach. I ask them to bore it out to 1/2" while I go find one.

Scrambling through the pits, I explain to the students the situation and they quickly find our hex broach. Since I'm out of shape, it's their turn to sprint to the machine shop with a part while I go explain more about the repair to the pit crew. I vaguely remember a member of the repair crew looking at me like I was crazy, but it was our only shot.

The gear makes it to the field with one match to spare and... it's too thick. They hand it to me and I sprint right back to the machine shop, asking them to take 1/8" off the gear. Fortunately, the 8th alliance called a timeout for an unrelated reason, which was just enough time for me to run back with the gear and for our wonderful pit crew to get it back onto the robot. We decide to line up for the 2 point goal, because frankly we have no idea what will happen to our robot in autonomous mode, and we all cross our fingers and hope this modification does the trick.

It does. We scored in autonomous that match, and while we were done trying to hang, our teleop performance looked completely unaffected. Just one change in code and we had our 3/3 top goal autonomous working every single match after this one. If we hadn't stopped hanging at this point, it would have looked like nothing had ever happened. This is one of my team's (and my own!) proudest moments in robotics. We didn't give up, we scrambled and improvised under pressure and it totally paid off.

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So there's our story. How about yours?

Curious, can you post the gearing spec on your arm? Every reduction + motor.

Then also the distance to CG of the robot from arm pivot, and the weight of the non-arm portions of the robot?

For random knowledge, the trick of dropping a tooth will work in a pinch on most gear setups, but you introduce a LOT of backlash and I wouldn't recommend it for high speed systems w/ lots of loaded direction change.

[coalhot]

Originally Posted by Lil' Lavery

Not that it mattered much against the 103+272+834 combo. They summarily trounced us.

This. One of the best finals in Philly I have seen, since 2008.

I remember MOE doing some last second repairs at Philly in 2010. Not sure If they were nightmare-ish repairs though.

Also, can we forget 75 at MAR and (I think) BE? The robot split in half, and they still fixed it.

[Chris is me]

Originally Posted by AdamHeard

Curious, can you post the gearing spec on your arm? Every reduction + motor.

Then also the distance to CG of the robot from arm pivot, and the weight of the non-arm portions of the robot?

For random knowledge, the trick of dropping a tooth will work in a pinch on most gear setups, but you introduce a LOT of backlash and I wouldn't recommend it for high speed systems w/ lots of loaded direction change.

Sure, I'd be happy to. We are well aware that we heavily exceeded a reasonable load on an aluminum pinion.

Input: CIM
Gear Reductions: TB3 Reductions (15:60, 14:50, 14:50) followed by two custom reductions (20:84 20:84). The pinion that failed was the final 20 tooth pinion. TB3 gears are steel as is the first 20T pinion, only the final 20T pinion was aluminum. No, that isn't backwards.

The arm failed both times when attempting to hang. Hanging hooks are roughly 2 feet from the pivot point. Base weight is about 75 pounds. I would say the CG is probably six inches forward of the pivot point (yes, it's far back).

[Taylor]

2006 Boilermaker Regional, 1319 had a small drive base and the top shooter was on a full turret. Either at the end of qualifications or in the first elimination match, they got smacked and the top 2/3 of their robot breaks off. Like dragging behind them.
First elimination match after that, they come out with just a drive base and play awesome defense. I think they won that match.
Soon after, everything's back, working perfectly, Regional Champions. Safety Award. Spirit Award.

[Koko Ed]

Our 2008 robot suffered a Catastrophic breakdown(the disaster occurs at 7:53 at the end of the first finals match which we won. Unfortunately we weren't coming back from this at that point. Ironically we won the Quality Award.

[Lil' Lavery]

Originally Posted by coalhot

Also, can we forget 75 at MAR and (I think) BE? The robot split in half, and they still fixed it.

Ramp Riot. Pretty sure they didn't play in either event after breaking their turret off. Not because they couldn't fix it, but because their alliances were eliminated in both of the matches the failures occured in. Somehow I doubt they would have continued playing even if their alliances had remained in it, though.

[Koko Ed]

One of the most memorable ones I witnessed was the last Canada's Wonderland event where 1114's robot unleashed a mushroom cloud in the finals. It was like time stopped right then and there.

[rsisk]

Originally Posted by Koko Ed

Our 2008 robot suffered a Catastrophic breakdown(the disaster occurs at 7:53 at the end of the first finals match which we won. Unfortunately we weren't coming back from this at that point. Ironically we won the Quality Award.

Judges worst nightmare....

And the Quality award goes to.... The smoldering heap of metal over there

[Koko Ed]

Originally Posted by rsisk

Judges worst nightmare....

And the Quality award goes to.... The smoldering heap of metal over there

John was chuckling while reading off the award.

[dcarr]

Originally Posted by rsisk

Judges worst nightmare....

And the Quality award goes to.... The smoldering heap of metal over there

Guess there is no "emergency second pick" in situations like that

[pmangels17]

At Duel on the Delaware (Fantastic Off-Season hosted by 365), we were #1 seed. We selected 341 as our first pick, and 1640 as our second. Then, in the semifinals, the giant lazy susan bearing we used on our turret snapped. The turret smashed onto the ground as we crossed the bump on the field. However, with the help of our great partners, and a six minute tme-out, we managed to get enough zip ties (approximately 40 normal size and 10 ludicrously large) onto the turret to hold it in place. It didn't spin for the rest of the day, but it worked in auton and for scoring, and we wound up winning.

Moral of the story: If you don't carry about 300 14 inch zip ties, you might not be prepared for your next inevitable breakdown.
Side note: 14 inch zip ties can be used for a number of things, including wiring organization, air tank mounting, turret repair, and mounting/securing almost any part on your robot.

[bnardone64]

Glad to hear your story, 2791. You guys did great, so close to a win. Maybe if that hadn't happened...

Team 1100 had its share of problems in eliminations at WPI. After the first match, the slider plates on our lift started to come loose. This wasn't a big problem so we got out our t-handles and tightened some and replaced some others. When we enabled the robot and moved the lift to make sure everything was working, the lift caught on some wires and cut one in half. The broken wire contacted the frame and short-circuited our digital sidecar. (although we didn't see the broken wire at the time) Over the next 4 matches, we ended up replacing the sidecar, our compressor spike, and a bunch of PWM wires, with no luck. We were able to drive after the first round of repairs and managed to win a match and advance to semis, but we didn't get the shooter back to working in time. We only found the problem in the pit after we were eliminated. We were able to fix it there in about 15 minutes.

Thanks so much, team 558 and 2370 for an amazing job keeping us in it for so long despite our problems. We look forward to competing at Boston and at the championships in St. Louis!

[Lisa Perez]

At the 2011 Traverse City District Competition, 830's planetary gearbox casing sheared itself in the middle of quarterfinal matches, and there was no way for us to bring it to the site machine shop to get welded in time for the next match. In a little bit of a bind and not wanting to completely forgo scoring capability, we decided to fix it by using screws to attach a piece of aluminum to the front, middle, and back of the casing to lock the segments together. I very vividly remember saying to one of the pit crew students, "Drill through the casing until you feel the outside of the ring gear or until I hear the change in material." Surprisingly, it worked up until the last 20 seconds of Finals Match #3!