pic: FRC488 - Six Wheel Drive Chassis

[Gdeaver]

I noticed that the front and rear c channels are notched for the drive rails on top and bottom. This could be a weak point. Shouldn't the drive rails fit inside the c channel leaving the channel uncut ?

[dlavery]

M -

Looks quite nice, and you have obviously put a lot of work and thought into the design. The efforts to minimize the total weight are obvious. The biggest concern you may have is strength in the event of an impact or collision. You might consider making the frame members out of rectangular tube instead of channel. Given the amount of material you are removing, the additional weight from the fourth side of the tube will be minimal, but there will a considerable increase in stiffness of the frame assembly.

Just out of curiosity, what is the spacing between the wheel sets? Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary?

-dave

[Cody Carey]

Oh goodness.

[ChuckDickerson]

Here we go again...

[Madison]

Originally Posted by dlavery

Just out of curiosity, what is the spacing between the wheel sets? Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary?

-dave

[Jeff K.]

Originally Posted by dlavery

Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary?

-dave

Any crocs?

CRIKEY!

[DanDon]

WATCH OUT!!! WE'VE GOT A DAVE ON THE LOOSE!!! SOS...SOS...SOS

[dfukuba]

That looks very nice and pretty well engineered. My suggestions are that you only use one set of omni wheels. You have to admit that you will be getting in to conflict no matter what you do.
The frame does look pretty sound, but with all that material taken out, are you worried about bending at all? these bots go through some pretty hard hits.
But i am very impressed by your design and i look forward to seeing the end product after the next hectic 6 weeks =)
--Dan

[Rich Kressly]

Originally Posted by dlavery

M -
Just out of curiosity, what is the spacing between the wheel sets? Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary?
-dave

Who keeps letting him in? Security!!!

I love the simple approach to the 6-wheel drive. I'll be follwing up later if you use this to see what additional stiffening was used/needed. Good luck.

[Madison]

Originally Posted by Rich Kressly

Who keeps letting him in? Security!!!

I love the simple approach to the 6-wheel drive. I'll be follwing up later if you use this to see what additional stiffening was used/needed. Good luck.

I took Dave's advice and added the fourth wall to the front and rear cross members as a start. Because these drivetrains are almost never operating absent some additional mechanism or superstructure, I try to incorporate those future additions into the design and allow for them to be used as support for the drive in the same way that the drive supports the mechanisms, if that makes sense. I try to design such that the finished robot appears organic -- not as if it was designed in pieces that were smashed together later.

Because of the holidays primarly, we haven't really done much of anything with our mecanum drive prototype. It still has no feedback system installed and remains difficult to drive. Most of the team agrees that, unless it appears to be a perfect solution for the new game, we'll stick with something more traditional like this drive, so there's a good chance you'll be seeing it somewhere.

[Andrew Blair]

Madison, I know that you have no broach capability, so I'm curious- where do you buy your #25 sprockets? I can't find any finished ones online, or in the Browning catalog.

[Madison]

Originally Posted by Andrew Blair

Madison, I know that you have no broach capability, so I'm curious- where do you buy your #25 sprockets? I can't find any finished ones online, or in the Browning catalog.

For this, we'll be ordering from McMaster-Carr -- part no. 2737T123. 5/8" bore was the smallest I found with a keyway for this particular sprocket. I didn't take a comprehensive look at many teeth counts, though, so I'm not sure how consistent the keyways are in 5/8" bore sprockets -- but I can't imagine why they all don't have one.

[Andrew Blair]

Ah, I see. We were going to be using 1/2" bore, and for some reason, no one on earth carries broached 1/2" bore sprockets. Thanks though!

[CE Mexican]

Originally Posted by dlavery

M -

Looks quite nice, and you have obviously put a lot of work and thought into the design. The efforts to minimize the total weight are obvious. The biggest concern you may have is strength in the event of an impact or collision. You might consider making the frame members out of rectangular tube instead of channel. Given the amount of material you are removing, the additional weight from the fourth side of the tube will be minimal, but there will a considerable increase in stiffness of the frame assembly.

Just out of curiosity, what is the spacing between the wheel sets? Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary?

-dave

I agree wiht what dave said about strenght, but on the contrary our team used aluminum channel for our frame and we didnt seem to have and problem with strength, and our frame took quite a beating during aim high this year

[CE Mexican]

team 1783, which is my schools team, used a different drivetrain set up, we had designed a setup where each side had indepent suspension, and two wheels for each side. and this year (depending on the game) i have designed a three speed gear box that would be incorperated into our original design. also i was thinking about trying out a four whee drive design that would be built by me and a local shop. how many of you guys know about the xmods remote control cars at radio shack? well i got one for christmas (god only knows why) but i was looking at upgrades for it and i saw that they have a four wheel drive kit for them. and after hours of configuring, and designing i think that i can build the 4 wheel drive suspension and drivetrain for our robot.