having just gotten back from working all day (11-730 or so) on rebuilding our wheel mounts due to bending during practice, I was wondering if any other teams had issues like this and had to rebuild after something breaking or not working in practice
We’ve had some issues with the robot bolts coming loose during practice – which reminds us that we need some locktighting.
Otherwise, we’ve been lucky so far. Last year, our toughboxes gave out couple nights before ship (gears completely gone bad)… But be glad that you’ve broke them now, instead of during the competition!
Team 2502
Luckily we figured this our early, but during he landing, our robot’s axles would warp, and the entire wheel mount would shift.
Luckily, we managed to mount some hardened steel bolts as shafts, and they’ve held up nicely.
this year because of a small programing error we made we nearly broke the winch in our robot that was pulling it up. the inside of it was supported by some pine that totally broke apart, so we replaced it with hockeypucks and it works great.
Not sure it would qualify as a rebuild, but a week or so ago, we decided to see what would break before the regional, so we purposely took the bot at full speed over a game field bump about 10 times each direction. We managed to crack one corner of the wooden floorboard, pulled one wire loose, slightly warped an omni wheel but we never killed the bot.
Our goal was to see if it would flip over, but since we had already decided to not turn on the side of the hill, it wasnt an issue. The center of gravity is nice and low so tipping over endwise shouldnt be an issue.
We have been using nylock nuts on all our major structural fasteners, easier than trying to remember what got loctite and what didnt, and they have not shaken loose so far.
Mike
We’ve done the same with our axles, hardened steel precision shoulder bolts FTW.
We’ve used nylocks everywhere as well, nothing’s come loose.
We’ve had some trouble with piston mounts, and some of our drive keys coming loose, but we’ve managed to fix everything so far. fingers crossed
I thought that rebuilding was standard practice for robot building. We always know that if you build it three time than you finaly have it right. We came up with some good designs that one week ago found that it did not function up to standards needed to play a solid game. So we tore it appart and rebuilt a complete assembly that works fine now. Trial and error after error teaches many lessons.
yeah thats what we did… backed our bot up to the back of one bump and rammed it full speed (~10 ft/s) into the other… it got over… but due to the way our mounts are, they were weak and bend on impact… then our bot went over and due to warped wheels and a bit of topheavy it flipped… nothing fell out though (velcro ftw) but yeah hopefully it should be MUCH stronger now… we changed the supports to be hollow aluminum tubes and added triangle supports… and are using bolts+nylock nuts to secure everything… here’s hoping its invincible now 
Geez, we have about (4) 2010 Robots just in broken parts.
Isn’t that normal?
We’ve had to rebuild or rethink:
- Lift winch (originally a toughbox powered by 1 CIM, pulling a cable through I-hooks - now a toughbox with 2 CIMs, pulling cable through pulleys) - didn’t get enough force originally
- Kicker latch release (originally a few hooks, now an entire piece of wood)
- Wheel setup (originally 4 “sticky” wheels, now sticky on 2 corners and slick on the other 2)
- The blue bumper for the right side (hanging over the corner by about 1/2"
Then there is the countless little tweaks that have gone into being able to mount our bumpers right (like having to drill giant holes in poly so that our wing nuts go on) and our lift arm deploying.
Now that our bot is programmed and running, we’ve just got a few little tweaks left before our second and last day of pre-ship testing!
We were basically all done with our bot but we realzed our wheels were too far apart so it didnt go over the bump…we have to take EVERYTHING off to fix that one issue. Now we are back to it being “mostly” done:confused:
Our breakaway bot hasn’t needed to be rebuilt yet, but it seems like every day that we’ve worked on the ftc robot, we’ve had to rebuild it at least once.
honestly what robot hasnt had to be rebuilt, modified, or repaired?
Our first shooter mechanism didn’t work right (we launched 1/4-20 fasteners across the room hard enough to chip a plate glass window - thank goodness for safety glasses!). We managed to work in a completely different launch system, but forgot some basic laws of physics regarding speed and torque. Once we dealth with the facepalm we sorted it out. Our hanging mechanism has ended up being benched and will be part of the 65 pounds we carry in - we have portions of it but don’t have time to debug before ship.
Just today we made a couple “minor” changes to the shooter that were major breakthroughs as far as consistency and durability. Now we’re focussing on the ball magnet. We have a system but we’re not happy with it. It works - but not to the specs we want. We’ll keep tweaking and trying other ways of doing things - that 65 pounds is pretty big this year.
All in all, it’s a pretty normal year. It wouldn’t be normal if we DIDN’T see the big-name teams carrying in huge chunks of their robot to refit prior to the first match being played at their first regional. Don’t let anyone fool you:
Very few teams are anywhere NEAR done at ship - and many of the top teams will end up completely rebuilding their bot once they see what’s working in competition, especially if any one feature or trick is giving a large advantage.
Heck, we’ve seen some large well-funded teams choose to sit out a huge portion of their regional while they rebuild their bot, then show up big in the last few matches and get chosen and do well in the elims.
Like I said - it’s a pretty normal year 
This season our team designed a worm gear drive system. Our sponsor has graciously been helping us with laser cutting and welding many of our components, but they’ve been very busy the last few weeks, and were unable to finish cutting the motor mounts for the worm drive in time for us to assemble. Our students tried to hand mark, cut, and assemble the mounts, but the alignments were always just a hair off, and the worms would bind up/draw very high current/stall while running under load.
After a few attempts to fix and drive with it, and only a week and a half left before the ship date, we scrapped the worm drive and went back to the reliable kit tough-boxes.
One of the advantages of the worm drive was having the motors tucked away in pockets next to the wheels, with the worms mounted directly to each CIM’s output shaft, driving a gear mounted directly on each wheel. Four motors on a four wheel drive system, and no chains anywhere. Many of our other components were designed to occupy all the free space left where chain would be.
With the scrapping of the worm system, and subsequent re-introduction of chain, many things had to be redesigned and rebuilt to fit wherever there was room, around chain and gearboxes.
The odd thing is, the redesigns gave us a second look at what we were doing, and we were able to improve upon many of the original designs. The resulting robot is much more capable than it would have been, and we’re really looking forward to competing in New York!
My team used 3/8 aluminium wheel axles…needless to say, after some gentle bump testing, they were TOAST
we upgraded to 3/8 Grade A Stainless Steel bolts…and after catching a good half-foot of air off the top of the bump at full speed, they are still straight as an arrow…but all that shock to the robot is making our electronics not like us 
we broke off a jaguar fan…it kinda just broke loose of its own little housing and started thrashing wildly inside the plastic casing, producing one of the most horrifyingly unique noises ever
we also had to modify our ball “dribbler” because the carpet that we had been teating it on before is different from the “spec” style carpet…
when we ran it on our quarter-sized field carpet today, our dribbler kept sucking the ball under our robot.
we build some “standoffs” with rollerblade wheels on the bottom so when the ball begins to get sucked under, it just rolls on the rollerblade wheels
all in all, everything is going great!
Good luck with finishing up your robot!