I hear a lot about how good the kit of parts chassis is (saves time for designing mechanisms), but what are some actual disadvantages to the kit of parts chassis?
Heavier than most custom chassis.
I would disagree with poor gearboxes, and poor performance. Those are just plain incorrect. Many successful teams use the KOP chassis, and the gearboxes are quite durable.
It’s an arduous process to change a broken wheel. I’ve heard the fastest KOP wheel changes are around 15 minutes and require disassembling that side of the drivetrain, compared to removing a single screw and washer on a WCD.
AM has beefed up the KOP wheels a few times over the past few years, so this should be less of an issue, but aggressive defense will likely run the risk.
Serviceability is definitely the biggest drawback.
So, while I will continue to be someone who advocates for lots of teams to use the KoP chasis, some of the disadvantages I know of are:
-Less customizability, both with wheel number and size and also with mounting for mechanisms. The dimensions of the chasis are also not easy to change.
-It is not as robust as SOME custom chasis.
-Tank style wheel mounting makes changing wheels take longer than it can on a WCD chasis.
-Weight, there aren’t really any good ways to “cheese” a KoP chasis as far as I know which can make it heavier.
some teams I have talked to complain about other gearbox options for it as it doesn’t have an easy way to mount vex gearboxes as well as mechanism mounting can be mildly challenging.
I will always be an advocate for the KoP chassis and my rule is “if you don’t know if you should use it or not, use it”. That being said there are some disadvantages compared to a custom drivetrain. The mounting is much more difficult since it is parallel plate along with servicing the KoP chassis being a pretty big pain. Another smaller one is how robust it is and how heavy it is but those are fairly small issues with it.
- custom (and vex) gearboxes can be difficult to mount
- inabillity to use 4" wheels and difficult for 8" pneumatic without the andymark kit
- severe rocking
- not aesthetically pleasing
- servicing is a pain. (Last year we had a belt that came off. Remove bumpers, squeeze hand in to unbolt axle, replace parts, tediously get on those spacers while lining up the axle through.)
We have been using the KoP chassis since our rookie year in 2017. This off season we are venturing off to try building a WCD to gain experience for 2020.
I agree with you the toughbox minis are good and durable. (We’ve never had a problem with them). The KoP chassis is great way for teams to focus more on manipulators.
I’d suggest a more thorough review of KoP users…
That’s a hot take, and a bad one at that.
I’m not denying your intel, but could you give some example powerhouses who use a strict KOP chassis? I can’t think of any off the top of my head.
Team 7457 won 2 district events and they used the KOP chassis
For starters, I would say there is a difference between powerhouse teams and successful teams , I would recommend checking out this thread, quite a few teams who have been successful with the KoP chassis have posted in here.
Preface: My team has used the kit bot 5 out of the last 6 years and in that time won 2 regionals, an offseason event, and were finalists in our division at worlds.
I am see many have rebutted your statement already, but I’m going to do it also as my team (343) has used a kop chassis since 2014 (except 2016) and we have every intention of continuing to use them for the foreseeable future, for all the typical benefits.
Do they wobble? Yes. Does every 6wd drop center wobble? Yes. Can a team do things to mitigate the wobble? Yes.
Are they bad defense bots? Lol nah, in 2014 (a notoriously defensive game) we figured out that we were really good at trussing the ball, then playing blocker for our alliance’s shooter because we went where we wanted and were hard to move. We also played defense with our 2017 bot. The trick to defense with a kitbot is to mount your battery directly between the motors as low as possible (yes this can be a pain to access, but the robot handles great)
The gearboxes are low quality? I assume you say this because of the plastic case, but our 2014 robot has been abused, 3 competitions, somewhere around a dozen Christmas parades on less than ideal surfaces, and hundreds of hours at demonstrations without a single drive transmission failure. My experience says those little toughbox minis are pretty bullet-proof.
Now, to respond to the original post:
Things we have found that we wish were better,
- We really liked the 4 inch wheels, AM, please go back to those with the appropriate gearing so we don’t have to change it later (this is an easy swap though if you want them)
- Accessing the drive transmissions if you blow a motor or something can be a major pain once the robot is assembled
- Wheel changes are a capital J Job, especially the center wheel which requires removal of that side rail (which you often have stuff mounted to)
To address the mechanism mounting issues people are talking about, We always replace/supplement the churros which connect the 2 sides with 80-20 (which is basically metal legos) so mounting is a breeze.
I too will continue to advocate for the kop chassis, but honestly, the biggest disadvantage to whatever drive base your team chooses, will be the part you throw together at the last minute just to get it done.
Sorry, I used powerhouse because successful is often arbitrary to a team’s goals.
You probably won’t see very many high tier teams using the KoP chassis because often times those are the teams who have the resources, experience, and knowledge to make it worth it to go with a custom drivetrain. You will see a lot of mid/lower tier teams with the KoP chassis because often times they don’t have those same resources/experience/knowledge in order to make it worth it.
I don’t think there’s ever been a time where I would say that a team was limited because they used the KoP chassis because it is still a great chassis.
The three issues I have with it are:
- its it harder to mesh with 1x 2 tube.
- I don’t like the wheels
- It does not give the team the opportunity to design a drive train (to me this is a disadvantage)
Else it is great.
Its a pain to mount mecanum wheels on it. We were glad to be able to opt out as quite a few past years chassis either sit untouched or have bee cut up to make brackets out of the aluminum. And I think next years robot again will be something in dimensions that fit the Andymark chassis so Andymark can keep selling them. I believe a lot is tailored rule wise to benefit Andymark and is coordinated with them So for example when they were selling the Tank Tracks it was pretty obvious we were going to have some rough terrain challenges. It’s both good and bad. That way there are assemblies readily available when the season starts otoh it makes some things predictable rule and challenge wise.