Chassis Types

[TheHolyHades1]

Hey guys,

We're beginning to plan for next year and we want to know what COTS options exist outside of the KOP chassis, and how they all compare. If you could please mention which chassis you use(d) and what drove you to that particular chassis system as compared to the other options that exist, and perhaps if you'd do it again, that would be wonderful. Things like versatility, ease of mounting things (such as bumpers, gearboxes, and vertical supports various systems), time to build, etc are appreciated.

What would also be great is if you do use a custom chassis, you mention why you decided to do that over other available options, and possibly what you learned from the experience?

So far, these are the COTS options that we know exist:

2014 KOP AM14U: http://www.andymark.com/AM14U-p/am-2563.htm
2013 KOP AM2239: http://www.andymark.com/product-p/am-2239.htm
VexPRO and WCP VersaChassis: http://www.vexrobotics.com/vexpro/we...sachassis.html
Drive in a Day: http://www.vexrobotics.com/vexpro/st...-in-a-day.html

Thanks,
Hades

[Christopher149]

For a slightly different (and older-style) c-channel chassis: http://www.vexrobotics.com/2005-kitb...omponents.html

[safiq10]

The Devastators used the AM14U chassis (wide base). We really didn't have any problems with it. We ran a 4 cim drive ran by belts with Vex Pro DT wheels. It was fairly easy to assemble. We made a cover for the top of the AM14U and attached all pneumatics and other things on top of that. With a removable plexiglass cover on top of all that. It was fairly versatile, we were able to play an amazing defense with this. Overall it was a major upgrade from the last years KOP chassis.

[TheHolyHades1]

Originally Posted by safiq10

The Devastators used the AM14U chassis (wide base). We really didn't have any problems with it. We ran a 4 cim drive ran by belts with Vex Pro DT wheels. It was fairly easy to assemble. We made a cover for the top of the AM14U and attached all pneumatics and other things on top of that. With a removable plexiglass cover on top of all that. It was fairly versatile, we were able to play an amazing defense with this. Overall it was a major upgrade from the last years KOP chassis.

With the wide base, do you have issues turning? We used an old wide base kitbot (2012) with 4 wheels, I think, and once we lined ourselves up against a wall it was basically impossible to move. The kitbot this year is drop center and 6 wheels, but with the poor experience in 2012 we decided to stay away from wide regardless.

[safiq10]

Originally Posted by TheHolyHades1

With the wide base, do you have issues turning? We used an old wide base kitbot (2012) with 4 wheels, I think, and once we lined ourselves up against a wall it was basically impossible to move. The kitbot this year is drop center and 6 wheels, but with the poor experience in 2012 we decided to stay away from wide regardless.

We actually turned really well just keep to the 6/8 wheel drive and you will see a great improvement. We also had trouble turning last year and we had 4 wheel mechanums

[Oblarg]

The AM14U is a huge step forward for kitbots; there are certainly some major things that need improvement (cutting it to size is a PITA and error-prone), but it's far better than any other kitbot in FRC history, by my estimation. It's also easily modified to accept better gearboxes than the standard plastic AndyMark ones (AndyMark's plastic gearboxes are something that I've never been pleased with).

I'm excited to see what they do with the kitbot next year; but I'd probably be satisfied using the AM14U again, all things told.

[nathannfm]

I have never used them, but AndyMark makes this http://www.andymark.com/NanoTube-p/am-0809.htm
which many of their chassis systems are based off of.

[z_beeblebrox]

221 Robotics Systems makes some drivetrains:

http://www.team221.com/order.php

[KevinG]

There's also 80/20, although it's fairly expensive and very heavy. I think C-Channel is a better option since the stresses these robots undergo aren't nearly that tough.

There's also custom options like making a chassis out of perforated angle. This site seems to offer a lot of interesting shapes: http://www.khodiyarcabletray.com/slotted-angle/

[Oblarg]

Originally Posted by KGenson

There's also 80/20, although it's fairly expensive and very heavy. I think C-Channel is a better option since the stresses these robots undergo aren't nearly that tough.

80/20 is a fantastic prototyping material, but if you're going to consider making a drive out of it there are some considerations you really should take into account:

1) Do not rely on sliders for holding chain/belt tension. They will work loose. If you feel you must do this, be ready to check them between every single match, and be sure to use a generous amount of loctite and brute force when tightening.

2) The corner blocks designed to connect at the end of the bar (with a bolt into the 1/4-20-tappable hole in the extrusion) are very good, and you should use them. Again, loctite is your friend.

3) Everything needs either loctite or a locknut. This goes for pretty much all constructions that use lots of bolts, but is especially pertinent for 80/20, where slightly loose things will slide all over the place (as opposed to just jiggling around a bit).

[Rynocorn]

Hey! I saw this and figured I would share what my team did this year. Previously, we had always built a slightly modified kitbot or a simple mecanum chassis (all out of U channel) but this year, as a senior and the first person on my team to ever really learn CAD, we decided to build a custom chassis.

One of the major factors in deciding to do it was incorporating 3 Cim Ball Shifters along with traction wheels for a fast, agile, and strong drivetrain as we wanted to stand out from the other teams in that regard. Seeing the obvious strengths of the AM14U, I decided to base the chassis on it by using the same dead axles, cross braces, churro tubes and parallel plate set-up and just reCAD and manufacture the outer sets of plates. I designed it as an 8WD system using Vex wheels and pulleys with dead axles and set the hole alignment perfectly using WCP center to center calculator and getting the plates made by on a water jet by one of our sponsors.

We had a ton of success with the drivetrain this year and it was our first time using the shifters and building our own chassis so I would recommend it to other teams out there. We did not lose a pushing match the entire weekend at Smoky Mountain and were faster than most of the robots there with both of our gears. It also required absolutely no maintenance the entire weekend! I designed it to be used in the future as well and if anyone wants the CAD or some help- I would move more than welcome to provide it/help!!!

Most if not all of the work can be done with a mill and bandsaw using careful measuring and drilling but much easier if a sponsor makes the plates. And most of the bending if metal (just two bends in the whole drivetrain) are not necessary.

Here is a link to our video and some/a picture of our robot!! Hope this helped!!

http://www.chiefdelphi.com/forums/sh...highlight=1466

[highlander]

Originally Posted by z_beeblebrox

221 Robotics Systems makes some drivetrains:

http://www.team221.com/order.php

These guys make a very well designed swerve; if you have the time/inclination I would look at this option. If code is an issue there are a lot of whitepapers on CD that can help you out.