Re: pic: 6WD Sheetmetal Chassis
 

They are bearings inside a bearing block for support.

Re: pic: 6WD Sheetmetal Chassis
 

yea I would lose them. All you need for a Dead Axle is a threaded rod with two bolts to hold it in place. 1/4-20 bolts will work fine. That is what we use, and dont have a problem with them

Heres and example of what I have designed. As you can see you don't need bearings for those wheels

Re: pic: 6WD Sheetmetal Chassis
 

Looking very good, especially if this is your first!
(Love the general configuration -- very 'wrangler. ;))

A few comments:
1. Is there any reason the front/back wheels need to be live axle? You're not tensioning them. My suggestion is to make them dead-axles, and make them structural. I love something called a "tube axle" here -- 1/2" OD, 1/4" ID tube, with a 1/4-20" bolt running through it. It'll stiffen things right up around the wheels (where it really matters!).

2. I don't like using sheet-metal as standoffs for gearbox plates. I recommend you use standoffs there, though other (equally as experienced) mentors would disagree with me, and have, loudly. YMMV.

3. You've got loooooots of rivets in places where it doesn't matter. That vertical row of rivets in the front bumper? Yeah... you need less than half of that. Hit the top and bottom hole, then space a few out in between. Then again, it doesn't matter -- rivets are almost "free."

4. Your lightening pattern can be a LOT more aggressive if you want. Even if you decide to stick with rounds, you can add additional smaller holes around your big holes. Remember the bumpers will add a lot of strength if done correctly.

5. Since you've adopted a "no belly pan" design -- make sure whatever upper structure you add provides torsional rigidity (helps prevent cross-corner flex). You can test this by holding three corners down, and lifting the fourth.

If you have the opportunity, build it, test it, and tweak it.
This is a low risk design which you should feel comfortable going into a season "cold" with, but another revision of lessons learned is worth its weight in gold.

Kudos again for a great first design!

-John

PS - Just noticed you're Potsdam bound -- enjoy Clarkson!

Re: pic: 6WD Sheetmetal Chassis
 

He is ALIVE!!!!

Re: pic: 6WD Sheetmetal Chassis
 

This. I went back and forth over integrating the gearboxes in Scorpion this year, and eventually decided to make the gearbox have two independent plates, and a big pocket in the frame, like mentioned above. It was invaluable when we had to service one of the gearboxes at the Dallas regional. Because we built the gearboxes independently, we could bring a whole spare gearbox, and when a screw sheared on the dog shifter, we just pulled the broken one out and swapped in the spare. A 10 minute fix instead of possibly 30 minutes or more. And even if we hadn't had a spare, it's still much easier to work on a gearbox that's on a table than one buried inside a robot.

So, while integration looks nice and is a little lighter... design for maintenance is important! A little thought ahead of time can save valuable time in the heat of competition.

Re: pic: 6WD Sheetmetal Chassis
 

Where do the encoders go? Here is where keeping a live axle wheel might be useful as it would be a simple way to toss an encoder onto a shaft. Other options (if you wanted to go dead axle) would be to use follower wheels, I believe 148 has a great picture of one from 2009 on CDM here.

Re: pic: 6WD Sheetmetal Chassis
 

Sorry I'm a bit late to the party on this, but one huge advantage to 5052 Al over 6061 Al is formability. 5052 is much more conducive to sheet forming than 6061 is (bending, rolling, etc). It is also easier to weld if you plan on implementing welds in your design. I'd stick with 5052 for a sheet metal design like this, but thats just me. I'm sure 6061 can be made to work as well with special considerations like large radii etc.

-Brando

Re: pic: 6WD Sheetmetal Chassis
 

We do our bent parts all out of 5052, and our flat sheet parts (gears, sprockets) out of 6061, for this exact reason.

Re: pic: 6WD Sheetmetal Chassis
 

For gearboxes, we actually used AM shifters with a final drive chain to a live axle. The gearboxes used 0.090" aluminum plates, and there were four slots in the frame where the gearboxes would bolt, and we could slide the entire gearbox up/down up to 3/4" or so to tension the final drive chain. The encoder was integrated into the AM shifter output. We really liked this design, and would do something similar again. The ability to change the final drive ratio was very nice, we changed it three times during the season.


On sheet metal alloy, we've had no trouble bending 6061 0.050" and 0.063" in our shop on a manual finger brake, but 5052 is easier to bend, especially thicker sheets. Using 6061 allows us to use thinner sheets.

Re: pic: 6WD Sheetmetal Chassis
 

Sounds like a very nice setup! Do you have any pictures to share?

Re: pic: 6WD Sheetmetal Chassis
 

I don't have any pictures of the gearboxes. I'll see if I can take some soon.

Re: pic: 6WD Sheetmetal Chassis
 

I took some pictures. Here are two.



The case bolts go all the way through both gearbox plates, the spacers, and the frame. There is a nut on the outer gearbox plate, then some washers, the frame panel, more washers and another nut. The frame panels have slots to move the gearbox up/down to adjust the chain tension of the final drive chain. The final drive ratio is 12:22, the final drive sprocket is an AM 22T with AM 500 hex hub. The CAD model will be released in the next week or so.