pic: 8-Wheel Chassis

This is a pretty complete drivetrain using the 2-speed gearboxes I posted recently. Total weight is 21.7lbs, excluding motors, lexan plates, and battery box. Outside dimensions are 28" wide, 32" long. The corners are 5" long, so the frame perimeter is exactly 112". Center 4 wheels have a 3/16" drop.

The corner gussets aren’t completely necessary, but my team has found that gussets like this help prevent broken welds late in the season. We have used 3D printed chain tensioners similar to the ones shown. These would be produced with 90%+ fill, or would be made out of ABS. The wheels in the picture are custom 4" wheels.

Starting the discussion thread for suggestions. Here’s the STEP file: https://drive.google.com/file/d/0B4POpKC2IAD9dkdSSXFQc1BMb0k/edit?usp=sharing

I am exstreamly interested in the octagon frame, and what design decisions did you use to come up with it what advantages do you think it will give you?

Why the 8 sides with such steep corners?

Looks good!

I would not set up the wheel axle bearings the way you have them now. I would definitely use some type of bearing block so that the bearing is well supported. Right now, all the load on the shaft is concentrated on only .125" of the bearing.

My team used a similar octagon frame this year, with 4.5" sides on a 45deg angle. These corners are 5" long in a 3-4-5 triangle arrangement. Although this makes for some weird angles, it means that all of the side lengths are whole, rational values (in other words, less math :stuck_out_tongue: ). Octagon frames have a few advantages:

-It allows you to have more inside surface area while staying inside a 112" perimeter.
-Defensive robots can’t hit your corners. This doesn’t sound like much, but any robot with omnis as outside wheels can easily be bumped out of position by a corner push.

Yeah, a bearing block would be used. The bearings in the model are just there to say that a bearing goes in that general area.

Hey I just noticed something

The dimensions are 28"x32", which makes a 120" perimeter. If the rules remain as the last two seasons, you can only have 112" if this were for competition

Remember by having the corners be diagonal like that you can keep within the 112" rules.

It would probably be helpful to read the post directly above yours, which explains how the chamfered corners allow within frame perimeter.

1310 did the same thing in 2013.