Re: What hath we wrought? 2016 Horror Stories
 

Don't use a 14t gear in a 3 cim gearbox.

Re: What hath we wrought? 2016 Horror Stories
 

'Nuff said.

IIRC 2640(HOTBOTZ) had a drivetrain motor burn out during a match. Their robot was pretty good, and they fixed it quickly, but one whole side stopped working properly at DCMP. Still an amazing performance with a broken drivetrain.

Re: What hath we wrought? 2016 Horror Stories
 

I learned that if the battery cables can be rocked back and forth at the battery or at breaker, they are too loose and will cause high current draws that shutdown the robot.
Same for the wires between the breaker and the power distribution board.

Add the bouncing over defenses, robot on robot contact, and loose power connectors to the radio either at the barrel plug or at the pdp and you get a dead robot.

If you can pull wires out of the pdp wago connector they are too loose.

Re: What hath we wrought? 2016 Horror Stories
 

Our active got drove upon during a match at champs, more or less had to rebuild it. Same thing happened at Minnesota State.
I chose to rebuild it for IRI, and it was a very good call because 233 more or less made a giant dent in it.

Oh and lots of chain was harmed in this season.

Not to mention 3 stripped gears in the WCP Double Reduction gearbox (we broke 3/4 that we had(got put out of commission for 10K lakes regional))

Not to mention the match at champs where we had our rear bumper ripped off our robot https://youtu.be/6FG63S24z1g?t=85

Not to mention two matches where our bottom plate ripped out and dropped our battery.

And lots of melted pneumatic tubing as we were running the 98C which gets really hot.

Honorable Mention: https://youtu.be/DDm56AZgHf8?t=73
The time we drove on the top of 2052 at MRI :D

Re: What hath we wrought? 2016 Horror Stories
 

I think we've broken almost every 3D printed part on our robot at least once

Re: What hath we wrought? 2016 Horror Stories
 

I'm surprised that nobody has mentioned the robot fire at Michigan State Champs yet.


Yeah. I could go with never seeing that again too :(

Re: What hath we wrought? 2016 Horror Stories
 

I call this match "New Drivers Vs. Intake Rivets"

https://www.youtube.com/watch?v=Ly654puHgZc

This is a good lesson about planned failure points though. If we had used steel rivets instead of aluminum rivets to hold the tubes making up our intake together, the intake would have broken further along, and in a far harder to repair place.

Re: What hath we wrought? 2016 Horror Stories
 

As you can see in the picture, 2781 flipped over, we (234) lost a bumper, and 461 dislodged a defense. I believe this all was in auto. Thank goodness, we were able to replay this match because of the field fault.

Edit: Also, all 3 of us are on the same alliance. This was at the off season event Boiler Bot Battle so correct colored bumpers were not required.

Re: What hath we wrought? 2016 Horror Stories
 

Unless those wires shorted to each other, that's probably not what was happening. Assuming everything was taped over as it should be per the rules and the inspection checklist, the loosening of your connections was increasing the resistance at those connections. Higher resistance with the same current (P=IR) means more power dissipated. More power dissipated means the main breaker heats up, and since it's a thermally tripped device, it opens faster shutting down your robot.

Either that or it's really loose and wiggly and you intermittently lose power. Even a fraction of a second will reset the RoboRIO and Radio.

It's a problem that pops up occasionally that often gets the attention of FTAs and Robot Inspectors due to the random shutdown. A bit of diligence when tightening and some lock washer (split, toothed, or other) will typically prevent such a problem. Although the extra pounding induced by the game this year may have challenged even those preventative measures.

Re: What hath we wrought? 2016 Horror Stories
 

About a week into October, the pancake on our gearbox decides to come unattached somehow. And second match at WMRI our robot's autonomous decided to go the wrong way and she ended up mounting one of the other teams' robots XD

Re: What hath we wrought? 2016 Horror Stories
 

Impressive, I don't think 125 broke any of the 3d printed parts on the bot last year. This included the entire intake roller being 3d printed.

Guess it just goes to show you that 3d printed parts aren't inherently weaker it's all in how you design and use them.

Re: What hath we wrought? 2016 Horror Stories
 

We were relatively lucky. We only blew a few pneumatic tires and stripped out the plastic VEX versahubs.

Re: What hath we wrought? 2016 Horror Stories
 

I mean, they are inherently weaker than injection molded parts - it's just a matter of if they are designed and built strong enough for the application. But your general point is right, I'm just being pedantic.

In general, this thread has many examples of design practices that are potentially fine being written off as universally bad ideas that can't work, or design concepts being blamed as the root cause of problems that they may not have been. 14 tooth pinions do not universally fail in 3 CIM gearboxes, for example, nor do plastic hubs.

If making a general rule and building very conservatively works for your team, that's great, just be sure not to give things out as general advice without a solid grasp of the "why".

Re: What hath we wrought? 2016 Horror Stories
 

You're right, the intent of "inherently weaker" was "inherently too weak". They are weaker.

Re: What hath we wrought? 2016 Horror Stories
 

Gotta have a solid frame for a game like this and for antics like these:
https://www.youtube.com/watch?v=FEKWdsOhAdY

Yes, the other team was slightly terrified we were stuck in high gear at the wrong moment without bumpers and nearly landed on them.

They also learned to keep the battery strapped in a bit better since it disconnected and flew from the robot.

We did drop to the floor once from about 4 ft from the ground during testing but I can't remember any other serious drops on the field. Most of the climbing failures just resulted in a slow and uneventful descent. I was more worried about drive components cracking than frame this year.