pic: 6wd prototype chassis
 

Re: pic: 6wd prototype chassis
 

What is the total weight on that?
I think 1/4in plate is overkill, but I will let others who have more experience comment on your design.

Re: pic: 6wd prototype chassis
 

It is.

I would have to add in that it seems that you have enough capabilities to machine out your own 2spd gearbox if you wanted to. They would end up being a lot lighter than the SS. Idk how the lightening pattern would hold up but how about 1/8" side plates? You'd still be adding bumpers (if that rule still applies for 09). Try to spread the battery and compressor weight in the back more unless the game calls for lumping their weight together in one corner like Overdrive did for many teams.

Re: pic: 6wd prototype chassis
 

5/8" sounds like overkill for me for dead axles. I would probably recommend 3/8" for that situation.

Just looking at that design, 7 sprockets per side of the drivetrain, with one direct driven wheel, looks way overkill. I'm not quite sure on the function of the extra four, but it appears to be some sort of elaborate chain run in order to use one chain per side. I would recommend using two chains per side with a double sprocket in the middle; one chain run from the front wheel to the center wheel, another from the center wheel to the rear wheel. This makes the chain runs nice and simple, as seen here.

1/4" plate sounds like overkill, but in this situation, it could be necessary to use [relatively] thick sheet metal to maintain rigidity in the chassis. If you have the capability, you might consider adding flanges, as seen in these photos. This would certainly make your chassis rigid enough to use thinner plate.

Re: pic: 6wd prototype chassis
 

Looks pretty nice the one thing I can tell you is that 3/16" is adequete for the side plates. That's what we've done for a few years.

The only thing I'm missing is how will adjust chain tension with this design?

Re: pic: 6wd prototype chassis
 

This is probably true. The ID of the bearings on the AM wheels are 5/8", so if we wanted to make it smaller we'd have to use a hub.

As it is, on the center wheel assembly there's a copper bushing (to decrease the 5/8" ID to 1/2"), the wheel, the sprocket, and a keyed hub to drive the whole thing. With this current design, I wasn't able to fit in two sprockets on the wheel assembly and have it all still fit on the extended output shaft of the gearbox. I suppose I could look around for other wheels that aren't as wide and it might kill two birds with one stone - the IFI ones might do the trick.

I'm not familiar with adding flanges, and I don't know if we have the capability of machining it. If we used 1/8" or 3/16" aluminum, would it be necessary to add flanges to ensure rigidity in the frame? If so, what size would they need to be?

Re: pic: 6wd prototype chassis
 

Which AM wheel is this? The Traction wheels have 3/4" ID bearings and are pretty wide.

The Performance wheels or Plaction wheels are both narrower and have a 1.125 diameter bearing bore (bearing bore Performance wheel is a separate option from hex bore). You can use 1/2" or 3/8"ID bearings in these holes (The performance wheel is provided with 1/2" ID bearings).

Re: pic: 6wd prototype chassis
 

Is there some reason you are set on a 6 wheel drive?

The simplest drive to build and maintain and program is a two wheel drive like the zero radius turn lawn mowers.

You simply drive the two rear wheels and put pivoting casters on for front wheels.

We do not know what this years competition is but if you have to go up a ramp or hill at an angle the two wheel drive allows for a suspension which is difficult to achieve with the 6 wheel tank drive.

Just my thoughts

Good luck