Sheet Metal vs Tube Drivetrain

[TheModMaster8]

Originally Posted by s5511

Our team has recently obtained a waterjetting sponsor and would like to build a new chassis over the summer. We are currently debating between building a full sheet metal chassis or a chassis made out of aluminum tubing (probably 2 * 1). We have noticed that a lot of the best teams, like 254/118 have used aluminum tubing in the past.
What are the pros/cons to using each on your drivetrain?

I've worked with both of these frame types before though their are different types of water jetted frame styles (http://www.chiefdelphi.com/media/img...9a78765c_l.jpg and http://shakopeerobotics.org/assets/images/robert2.jpg) If you use a folded frame design, you will need to get it bent by a powerful/precise machine (might be able to be done manually depending on material,thickness and length of part).
Water jetting is nice because you can have a frame cut out and ready to be assembled in about 30min-1.5h depending on the complexity of the design (if you have direct access to the machine that is...)It's also easier to jet spare parts, and is lighter then tube (If designed correctly). Some of the cons however, is that it is fickle when bending it (you might get a perfect 90 deg bend or not). It needs a lot of bracing to make the frame stable and rigid.
(for my team) when we got our frame bent, it bowed the metal in a arc making a 1/8 gap in the middle of the part when laid on a flat surface.( This was most likely the bending machine's fault as well as the settings on the machine).

What are the pros/cons to using belts vs chains on your drivetrain?

Belt is better (IMO) it has vary little, too no slack at all. Making it precise. it doesn't stretch nor does it brake (Vex's Belts other brands will though)
Chain normally (in my experience) is a flipping nightmare, chains stretch, masterlinks brake, sprockets strip, etc,etc.
Here is a document found on vex's website "Belt vs. Chain Drive Evaluation" by FIRST Robotics Competition Team 234(credits to 234!)

Hope this has help in some way