pic: 6WD Design Iteration

[wilsonmw04]

Being from a team that does not have an in-house machine shop, this design is very interesting. What are the outside rails made of? Is there some sort of track that the wheels are sliding on to provide tension?

[lukevanoort]

Originally Posted by wilsonmw04

Being from a team that does not have an in-house machine shop, this design is very interesting. What are the outside rails made of? Is there some sort of track that the wheels are sliding on to provide tension?

The outer rails are made out of T-slot aluminum extrusion, probably made by either 80/20, Bosch Rexroth, or Item (In this case, I think it is 80/20). Specifically, it looks like either 1.5" (40mm if metric) or 1" (25mm if metric). The pillow blocks are probably held in by t-nuts and you'd just loosen the t-nut and slide the wheels to tension. One of the wheel pairs (looks like the front ones) is usually powered directly off the output of a transmission (like an AndyMark SuperShifter). This one could also power the rear wheels by chain and transmit power from the rear wheels to the front.

Although this is much simpler than the West Coast drives that you see made by teams like 254, 4, 968, 60, etc., it probably would be a challenge to make without a machine shop (due to the custom machined pillow blocks). You could probably make it without a machine shop if the outer wheels were running on dead axles (eliminating the need for accurate pillow blocks) and if the center one was directly mounted onto the output shaft an AndyMark SuperShifter (probably using the extra-long output shaft upgrade). You could then use bumpers to protect the chain runs from the center-front and center-rear wheels from being damaged by other robots.

BTW, this design is great! It is definitely going into the collection of possible drive designs for next year. If we are collecting balls again (or something else that requires a ton of vacant space in the center of the robot) I'm definitely going to propose this. Great work, Madison!

EDIT: Okay, now I'm almost 100% certain that it is 80/20 extrusion, because I see some 80/20 Quick Frame in the middle holding in the battery. Between the the smallish extrusion on the sides, C-channel front and rear, and the 1/16" wall tube in the middle, this thing must be pretty dang light.

[maclaren]

I like the design!

A couple of questions:

What wheels are you planning on using?

Do you have a weight estimate?

What transmissions are you planning on using?

[Gdeaver]

The inner rails appear to be 8020 quick frame material. I would be careful with using the 8020 quick frame connectors when they are going to be subjected to allot of stress. This year our team may use the quick frame material however for stressed and load bearing connections The E-Z tube connectors are much better. They do not match the Quick frame tube dimensions but, a little filing takes care of that. They are available with and without internal steel welded reinforcement.
http://www.eztube.com/connectors/connectors.html
If the Quick Frame flange tube was used you would have a support for a board to lay in the center to add stiffness and mount stuff. How are you going to attach the quik frame to the c channel?

[Tim Delles]

Few things:

Looks like a lot of stress to put on 2 "rails"... Have you checked to see how this set up will take the stress (seems like thin material to be using)

Also as for cantilevered wheels: i wouldn't do this. First off if they aren't very well protected it is easy to play defense on you (i.e. stopping you from driving around)

Also why not use all 6 traction wheels with the centered one lowered (similar to the kit chassis) as this will make sure you have full surface contact and will make it harder for a team to "spin" you around.