pic: 1726 Overdrive Chassis CAD

This is an inventor model of our chassis for this year. 6wd with 4 inch IFI wheels mounted on cantilevered dead axles. The frame is made from pultruded fiberglass c-channel with a .063 aluminum baseplate. The transmissions are Toughboxes with one of the stages taken out (lowering reduction from 12.75 to 3.57) and the wheels are driven by a single chain per side. Estimated weight is 40 lbs (wayyy too light…).

I have a 4’ x 4’ x 1/4" sheet of steel if you need some ballast.

Or, if it just needs a little bit of ballast, we could use the magnesium anvil

the ifi wheels bend extremly easily, we used them one year and got hit once that was it… the hit wasnt even very hard but the slightest bend and the wheel is scrap, u can reposition it but it never runs the same. so cover them!:o

bumpers are not shown, but will be added of course (per the rules)

Thanks for the suggestion too, perhaps we oughta buy some spare side plates for them? although if you used the IFI wheels from 2006 or earlier, they are a different design…we used the new ones last year and didn’t have any trouble with them, although they were well protected

If you are going to use cantilevered wheels with such a system I would suggest that you weld your dead axels to a large metal plate and then bolt this plate to the fiberglass. Otherwise you will be concentrating a large force on a piece of material that is only 1/8" thick :ahh: I would be worried about an axel tearing out.

Another obvious solution to this problem would be to use a thin sheet of fiberglass to support the outer side of each axel. This would also give you a place to mount the bumpers.

just use gold old normal concrete

The c-channel is 1/4" thick, and we are going to use 1-1/16" flange nuts to mount the axles. Also, the wheel is pretty close to the c-channel, so there isn’t a huge load on the axle.

You might want to provide some sort of channel to house your wheels that you can run the axle to so it is not cantilevered. This also provides a mounting base for your bumpers. That way you will fulfill the rule of having 2/3rds of your robot with bumpers around it.

We will have bumpers all the way around the robot, and the cantilevered axles are definitely strong enough, and are well supported. The Inventor rendering does not have all the parts on it…so you can see the interesting stuff…but there is more to the robot!

We used a fiberglass I beam turned on it’s side for the main frame rails on last years robot, with a thru bolted dead axle. It was quite a bit harder to build, this year we are going for maximum ease of construction, along with a solid, reliable, effective design. We’ll see how it does.

Hopefully we’ll get some ball handing mechanism pictures up in the next week or so. The catapult experiments went well today, it behaves very safely when not loaded with a ball, and shot a 30" exercise ball (using 1/4 the final pneumatic cylinder capacity) almost high enough to clear the overpass.

Should be fun!

Today we built the transmissions and put an axle on a scrap piece of c-channel to test how strong it is. The axle setup is very solid, and i can’t see it breaking under any load the robot will see.


My team has used a cantilevered dead axle system for the past three years with only one major issue that i can remember: bumper mounts. Last year’s solution, which proved to be waaay too much trouble was to tap holes into the axles to receive the bolts from our bumpers. May I suggest that you consider integrating mount points into the frame. (I’m pretty sure you already have an adequate solution, though.)