Best simple robots based on kit chassis?

[GeeTwo]

Originally Posted by frcguy

Just trying to show you can build good robots on the kit chassis.

My advice is to find some way to turn this assertion around. That is, until you have proven that you can build a good robot on a (suitably modified) kit chassis, don't even think about building your own chassis. Here, I'm defining "good" as better than (oh, about) 50th percentile seeding at a local event. Once you meet this threshold, seriously think about whether spending more time on a drive train is worth it to your strategy. Unless your team is dripping talent, the answer will probably be that a custom drive train is only worth doing when the game presents unusual challenges.

[Sperkowsky]

Originally Posted by GeeTwo

Unless your team is dripping talent, the answer will probably be that a custom drive train is only worth doing when the game presents unusual challenges.

I respectively disagree. Something like a simple west coast drive is really not that much more difficult then using a KOP drive train especially if you are going to go out of your way to modify it. Plus mounting gets easier and you are not restricted at all in terms of sizing.

[Jay O'Donnell]

Originally Posted by Sperkowsky

I respectively disagree. Something like a simple west coast drive is really not that much more difficult then using a KOP drive train especially if you are going to go out of your way to modify it. Plus mounting gets easier and you are not restricted at all in terms of sizing.

While you may be correct about the physical advantages and difficulty, the biggest resource a team can control by using a kit chassis is time. The chassis can be built in a matter of hours, whereas any custom chassis will take multiple days.

[Richard Wallace]

Our last three chassis have been:

2014 -- souped-up 6WD kitbot
2015 -- semi-custom 6WD-plus-drop-strafe using VexPro clamp-on-tube gearboxes (see Sam's plug earlier)
2016 -- souped-up Rhino track drive

We like starting with stuff that others have developed, and tweaking it to suit our game play priorities.

As Dave said long ago, steal from the best, then invent the rest.

[Rangel(kf7fdb)]

In 2013 amd 2014 we used the kit bot chassis in order to save time. Both years we won our states regional and in 2014 had one of our most successful robots reaching the semifinals of our division. Unless the game is very drive train intensive where a good drivetrain will score you points such as 2016, I would just stick to the kit chassis.

[messer5740]

Our robot used the upgraded kit of parts chassis with the pneumatic wheels. We took an angle grinder to the front of our chassis so we can pop ourselves over the rockwall and the moat. You can easily do well with a regular kop chassis if you modify it to your needs. Here's a few pics you can't notice the angle on the front because we made it at our competition

[jijiglobe]

Team 694 won Curie this year with a kit chassis bot. It wasn't exactly a simple bot so you might not want to include it in your list, but it does technically fit the bill.

[philso]

Originally Posted by GeeTwo

Unless your team is dripping talent, the answer will probably be that a custom drive train is only worth doing when the game presents unusual challenges.

It is common in the working world to use off the shelf parts where possible to save time and effort and get to market quicker.

Originally Posted by Sperkowsky

I respectively disagree. Something like a simple west coast drive is really not that much more difficult then using a KOP drive train especially if you are going to go out of your way to modify it. Plus mounting gets easier and you are not restricted at all in terms of sizing.

The lack of restriction you see as an advantage can also lead to a trap. One can spend a lot of time figuring out where to mount the components and optimizing it over and over.

Originally Posted by Jay O'Donnell

While you may be correct about the physical advantages and difficulty, the biggest resource a team can control by using a kit chassis is time. The chassis can be built in a matter of hours, whereas any custom chassis will take multiple days.

There is also risk that you are not able to get all the needed parts manufactured correctly in time. A few years ago, a team in our area that had been part of a Einstein winning alliance spent the Thursday of their first Regional completing the assembly of their robot. Their sheet metal sponsor delivered their parts just a bit over 24 hours before bag and tag so they had to bag an incomplete robot along with all the uninstalled parts (it didn't even have wheels installed). The imperfect COTS parts you have in your shop will perform much better on the competition field than the perfect custom parts you only have CAD drawings for.

Originally Posted by jijiglobe

Team 694 won Curie this year with a kit chassis bot. It wasn't exactly a simple bot so you might not want to include it in your list, but it does technically fit the bill.

This robot should be included. The time they did not spend developing a custom drive train (probably giving only a small increase in performance) was probably spent on developing the scoring mechanisms and practicing, allowing them to perform well enough to become the Alliance Captain and win the Subdivision Championship.

[OccamzRazor]

Brief message on top and the explanation below.

The best kit bots usually happen in games where the field is flat and most of the field elements are simple like 2013 and 2014. Those robots are usually not as optimized as well as many of the ones you guys have posted.

I would say if you have the capability to customize and form a proper custom chassis then that solution is preferable to using a kit chassis. It is also easier to go "custom" than people believe!

If you have a decent drill press or even better a mill then you can easily create a Vex Pro WCD by buying a step/cone bit from harbor freight or home depot. Cost is not an issue if you get the voucher instead of the kit chassis in your kit of parts because you can allocate the $400 to buy everything but the chassis such as motors and wheels. We end up saving money, weight, and time by doing this.
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Here is why I say this. I have plenty of experience using the kit chassis since they actually started to provide it in 2005. Anything prior to that for us was 100% custom. When I started my current team we used the kit chassis for 2011-2012, made a custom chassis using 221 Robotic Systems in 2013, used another kit chassis in 2014, and then switched to Vex Pro WCD for 2015 and 2016.

We loved the switch from kit to custom in 2013 and that Cadillac of a robot chassis still runs perfectly today (thank you Anthony). We purchased these components and did not make them which means it set us back a lot more on budget.

We did not have the budget in 2014 so we went with the kit again. See the pattern here? Custom is the way to go if you have the money, or capability to save on the cost do it in house. If you have neither then stick with the kit. Vex Pro products gave us the capability to do in house custom chassis because they are simple.

When we switched to vex pro it became a lot easier/cheaper for US to make the drive system because you do not need nearly as much dimensional accuracy and the frame rails can be made easily. You could even use a drill if you were careful enough. Since the bearing blocks slide on the tubing it is easy to correct mistakes and it is very forgiving for people new to manufacturing robot drive systems.

With the kits, you are often up and running very quickly on the floor and they are easy to put together....until you decide to add bumpers. Or that shooter turret. Or that arm that you made out of 80-20. Or that metric stuff you had laying around the shop and works perfectly on your prototype...how do you attach that again?

What I am getting at is that the kit bot is rarely going to fit your design without some compromise and I have seen enough teams compromise their designs because of the kit chassis they did not want to sacrifice. Some teams did sacrifice their kit chassis in a different way this year by choosing to use it with the stock polycarbonate wheels on those nice steel defenses or modifying their chassis in well... less than structural ways. On games where the floor is flat and not filled with wheel cracking shapes I am sure that would have lasted all season. Since you never know what the game is before you decide whether to get the kit bot or the voucher, we usually just get the AndyMark voucher because we can purchase the kit anyway if we change our minds.

[BrendanB]

One team I'd give a nod to has been 4909 Bionics. I believe their rookie robot in 2014 was the only year they ran a 100% stock kitbot and have made slight modifications in the following years to better fit the game. 2015 they added mecanum wheels as their strategy was to make capped six stacks by splitting the stack placing totes and then capping them after. 2016 they stuck with 6wd adding large Colson wheels and modifying the frame slighly using the older kitbot style C-Channel framing so their wheels cleared the frame allowing them to cross the defenses.

The simplicity in their drivebase has allowed them to focus more on the upper mechanisms and completing them before bag day. Its a good strategy sticking with the #1 design rule of taking inventory of what resources you have around you and using them to their maximum potential. Aside from their first event as a rookie where they finished 15th they've always been in the top 10 at their events, qualified for the District Championship all three years, and just barely missed the finals this year at UNH.