Never Do This, and Other Good Ideas Gone Bad

[TD912]

We were in the same boat at thefro526.

We had probably one of the cooler-looking but worst-functioning robots at the NYC regional. It was mainly due to improper testing, as we would need the air tanks to be full to lift. That meant no kicking near the end of the game or we wouldn't raise fast enough.

Here's a photo of our lifter.


And when it's collapsed:

[Alex.q]

My 3 years in FIRST have taught me many ways of how not to build a robot.

'09: Instead of belts, we used some sort of fabric for ball collection, ending up with a burned up (globe?) motor.
Lesson 1: make sure you have enough torque
Lesson 2: Do research online of what other teams are building so that your team doesn't have to invent everything themselves.

'09: hopper + small opening + turret = I don't know how many times we were even able to shoot because it was always jammed.

'10: I'm not sure how to say this other than don't use your frame as the stopping point for a extremely strong bungee powered kicker. Especially if you cant replace bent pieces because the frame is welded. (Also, this kicker sent a mentor to the ER after cutting his hand between the "foot" and the frame. Avoid dangerous pinch points if possible)

'10: if you have a piston that resets another mechanism (in our case, the piston pushed the kicker into a gate latch than retracted), keep the piston connected to what ever it is actuating. We made a catch for the end of the piston, but this often turned sideways and hence didn't work.

'11: If you build a swerve drive, make sure you test it in game-like condition. We prototyped in the fall (never truly testing it), and due
to slow turn around time from our manufacturer, the programmers didn't get a lot of time with it. Luckily, the programming and mechanical aspects worked for the most part. Unfortunately, the one optical encoder that told the wheels which direction they were pointing was not high enough quality and returned random values. Result: our drivers never knew which way the robot would move. While we were able to fix this with a better sensor in our second regional, this problem ruined an entire regional for us.

[s_forbes]

With the season wrapped up, this should be a very hot topic for a lot of teams!

As fun as it was to design and build, I would take our arm design for this year off of my list of "Things we should do again". I'm glad we were able to pull it off, but there were a lot of headaches involved.

Fortunately, I think our list of things we did right this year greatly outweighs our list of things we did wrong. Usually it seems the other way around.

[sithmonkey13]

On 1178 (D.u.R.T.), we have successes in some areas, and some pure luck in others.

In 2008, we implemented a scissor lift that lifted the ball up to deposit on the rail. Once the drivers got used to it (the whole robot was named Manny), it worked marvelously, although it used pneumatics (several of them) to force the lift up. We still drive the robot around, as it is one of the most visually impressive robots we have.

In 2010, we learned that a powerful pneumatic kicker can and will kick itself to pieces if shoddily crafted. We also learned that bending the frame and wheel brackets made the drive train unusable in some matches.
In 2007, we used the Banebots planetary gearboxes, and they are still working (though we would not use them again if we are able to use AndyMark's or Dewalts)

2011- We decided that we would use meccanums and a continuous lift, both of which we had never prototyped before. Due to the awesomeness of AndyMark components (our whole drivetrain was AndyMark components), the direct drive meccanums worked marvelously. Also, we paid a lot attention to making the lift right and getting it working (the biggest issue was belt tension, and using a window motor direct driven to the belt).
We have also decided that until TI improves the Jags, we are not using them as they present too big of a safety hazard (we have had multiple fail this year while driving, and one caught on fire).

Sorry about the disorganization of this post, it was pretty much all train-of-thought as I procrastinate from homework.

[legogeek24]

Suction cups are a bad idea. 1569 attempted it in '07 and almost never was able to adequately pick up and place the tubes, forcing the robot to rely simply on the ramps. Awesome as they were, they weren't enough to get picked in the eliminations due to the lack of scoring capability.

[The Cyborg]

Former team #65 in 2007- Using a plastic sprocket to drive the elbow joint of an arm. At the finals in their division, I believe an opposing robot rammed into the arm, putting a lot of force on the joint. You could probably guess what happened next.

Oh, and only one plastic sprocket was made for the robot.

I didn't even know that plastic sprockets existed for anything outside of toys and Vex Robots.

[hallk]

Epoxy works great when you use it on it's intended materials that have been properly prepared. It doesn't work work quickly at all and expecting it to hold together for the next match in 20 minutes will never work. It is also a disaster when someone loses the caps to the epoxy and then just puts it into a plastic bag at the bottom of the tool bag.

Trying to speed hole extruded Aluminum will just result in bad things.

Based off this year's experience with mini bots, don't use Tetrix motors and expect them not to fry.

Make sure to pack your controls.

Not robot related but..don't let someone handle the bookkeeping if the have no accounting knowledge. Make sure someone goes over said books before the night that the sponsorship application is due.

[Billfred]

Something we learned the hard way at Bayou 2010: Don't put off numbers if they have to go on the bumpers...if you're having to use paint outside, the result will look like crap.

JVN's silver Sharpie tip was a revelation this year, though that still took us a couple of hours in our shop with a small group of people tracing and going back over the numbers a few times. (I think we put at least three or four coats on our robot's bumpers, which we did with a rather thick stroke--we bought six markers and had usable ones afterward.)

I wouldn't want to do anything resembling that level of effort in the pits ever again.

[Tristan Lall]

Originally Posted by Billfred

JVN's silver Sharpie tip was a revelation this year, though that still took us a couple of hours in our shop with a small group of people tracing and going back over the numbers a few times. (I think we put at least three or four coats on our robot's bumpers, which we did with a rather thick stroke--we bought six markers and had usable ones afterward.)

To make the numbering process faster, couldn't you cut the markers open, extract the plastic-wrapped felt ink reservoir, and use it like a big, wet crayon? (Who cares that you can't write with the markers anymore? And if at a competition, there will be plenty of other teams with inadequate bumpers who could benefit from the leftover ink.)

[Billfred]

Originally Posted by Tristan Lall

To make the numbering process faster, couldn't you cut the markers open, extract the plastic-wrapped felt ink reservoir, and use it like a big, wet crayon? (Who cares that you can't write with the markers anymore? And if at a competition, there will be plenty of other teams with inadequate bumpers who could benefit from the leftover ink.)

I haven't experimented with this--in our situation this year, we had some time, plenty of cheap labor students, and me leading the process in clothes for work that didn't need to be silver if I could help it.

Unless we were in a panic, I'd probably keep with how we did them this year (better photo: http://twitpic.com/40kj4i)--the only improvement would be a true stencil. (We traced old iron-on transfers that we used unsuccessfully in 2010--but we didn't have a 5, so we improvised it using other numbers we did have.)

Of course, if someone can show how it's done (and without creating a total mess), I'm all ears.

[Molten]

This is more of a bad idea gone bad but it certainly applies to the side topic of team numbers on bumpers. In 2007, 1766 forgot to have our numbers on our bumpers and had to improvise at the competition. Going pit to pit we found a team that had some paint and got permission to borrow it. We cut a stencil out of paper and cardboard and went outside to spray it on. In the end I held the bumper with one hand while spraying with the other. My arm had orange on it for the rest of the competition. I would give credit to the team that gave us the paint but I can't remember the number. It was a tiger themed team at the buckeye regional in 2007 if anyone else recalls the number.

My point to all this is that there is always a worse way of doing things. I never once thought of a sharpie and immediately went looking for paint.

[pfreivald]

Bumper skirt.... Bad idea. They almost got us DQ'ed at FLR.

Next year we'll be making two sets of bumpers!

[rsisk]

Originally Posted by Billfred

JVN's silver Sharpie tip was a revelation this year

Also, don't use the bumpers as pillows after you have used the Silver Sharpie Technique, the numbers will transfer to your face. Not that I have first hand experience after the all nighter Monday before shipping or anything, just sayin....

[Andrew Schreiber]

Originally Posted by rsisk

Also, don't use the bumpers as pillows after you have used the Silver Sharpie Technique, the numbers will transfer to your face. Not that I have first hand experience after the all nighter Monday before shipping or anything, just sayin....

Pics or it didn't happen.

[efoote868]

If its rated for 25lbs, it probably doesn't have a safety factor of 4, and it probably can't handle 100 lbs.
The "Little Pulley that Could," couldn't.