pic: 1503's Off-Season Project
 

Re: pic: 1503's Off-Season Project
 

Very Very nice work! Time for some questions. How heavy is the entire thing without electronics and with electronics? Are those the banebots wheels? If so how are they holding up and how is traction? Does this drivetrain have the ability to climb ramps and if not would it be easy to modify it? How are the chains tensioned?

Overall I love this design and it looks very similar to many of mine. Good job guys!

Re: pic: 1503's Off-Season Project
 

Love the double banebot wheels--we had a similar idea.

Nice looking transmissions as well--are those 4-speed?

Could you give us some performance numbers for those of us who cannot access YouTube from our non-home computers?

Nice clean look! A great layout example for other teams with the new control system.

Re: pic: 1503's Off-Season Project
 

Pretty impressive perfomance, seen it over the weekend...

Clean design as usual. Looks like the team is doing great.

Re: pic: 1503's Off-Season Project
 

30 Shore A wheels! :eek:

And to think we had too much traction with 70-75 Shore wheels, and they wore through .5" of rubber over the season :eek:

It does look very cool though. The apparent lack of tensioners is especially clever :cool:

What are you planning to use those extra drive sprockets fore? Drive-train powered mechanism?

Re: pic: 1503's Off-Season Project
 

All I can say is WOW. Great job!!:ahh:

Re: pic: 1503's Off-Season Project
 

Does that thing have a 4 speed? And i love the layout you have no idea, very slick and very compact

Re: pic: 1503's Off-Season Project
 

I'm lovin the green and red wiring.

That is a very impressive drivetrain. Nice work!

Re: pic: 1503's Off-Season Project
 

A couple of questions of my own:

Since you're running traction on all 6 (12) wheels, how much have you dropped the center wheels?

I've heard some reports of the banebots wheels blowing out, have you done any durability testing on them yet (getting pushed sideways and such)?

--Ryan

Re: pic: 1503's Off-Season Project
 

I agree, the layout is amazing!
The mix of 80/20 and custom frame is really well done too.
I wonder how well the wheels hold up while making a sharp turn though...

Re: pic: 1503's Off-Season Project
 

That's hot Pat... You deserve another cookie for this.

Interesting that you used 80/20 and #35 chain, looks like a 4 speed shifter. Good work again by Spartronics, see you guys at GTR.

Re: pic: 1503's Off-Season Project
 

What's the weight on that?

How easily can wheels be swapped out? These wheels were field tested by a lot of combat robots at robogames, and they found them to wear down quite fast (and that was on steel).

and purely out of curiosity, is the electrical board garolite?

At Robogames the wheels themselves proved to be rather durable, the tread layer is just a lot thinner than they appear and since they are a very soft rubber, wear down rather fast.

Re: pic: 1503's Off-Season Project
 

Thanks, everyone, for the comments.

We never measured it without electronics; with them, it's sitting at about 60 lbs (sans compressor). Of course, there are 26 steel gears in there, most of which we'd weight-relieve for a competition robot.

Yes, they're the 30 Shore A Banebots wheels. We're really happy with the traction, and may switch to a harder grade if they wear down too easily. We're prepared to switch the wheels out fairly often since they're $5.25 each and a couple of minutes on the CNC takes care of the mounting holes.

It should be able to climb most ramps just fine. If not, we'll just mess around with ground clearance (currently 0.75") and wheel spacing.

As with our 2008 robot, the wheel spacing is such that the chains are an integer number of links. I've always been wary of over-tensioning chain, and would rather avoid the friction and added complexity of tensioning systems. If the chains stretch and become too loose, we'll just replace them.

Yeah, they're 4-speed transmissions, inspired largely by AndyMark but entirely custom (with a shifting mechanism that addresses several maintenance-related issues we had with our Gen 2's last year as well as making the parts much easier to machine with our shop). From a drive strategy perspective, I wanted a 3-speed, but decided that the best way to accomplish it would be to design a 4-speed and just not use one of the speeds. The (calculated) speeds are 5, 9, 11 and 19 fps, with the 9 fps speed being ignored.

We mostly picked those wheels for now because they match our team colours. :) The sprockets are there for now so that the front and back wheels are interchangeable.

The center wheels are dropped 5/32", same as our 2008 robot. Given the flat nature of the wheel tread as compared to the roughtop we used last year, though, I'm thinking we could probably get away with less.

We haven't done any extensive field testing yet. We cut some wheels apart and were happy with their composition and with the way the treads are bonded to the wheel, but breakage from a side load is still a potential issue. Our attachment point to the wheels is fairly far from the axis, though, so I'm not overly concerned.

Geez, all this talk of cookies, and yet nobody ever follows through... :p
The extrusion is actually Bosch; we were lucky to obtain it for free. As for the chain, I know that by the numbers, #25 is perfectly acceptable for drivetrains, but it's less forgiving of slight misalignments and stretches more readily. I'd rather waste the weight on #35 chain and be secure in the knowledge that we're never going to have issues with it in the heat of competition.

It's just a matter of sliding the axle out. We'll have an extra set of wheel assemblies ready and a bunch more pre-machined wheels for swapping with those on the inactive set.

Not positive, but I think so. It was a piece of some sort of fibrous composite that was kicking around our back room. On a competition robot, though, I'm leaning towards using carbon fibre.

Re: pic: 1503's Off-Season Project
 

Very cool chassis design! The four speed transmissions look really neat, what kind of shifting mechanism are you guys using? I wasn't aware of any issues with the AM dog shifting design, but I'd like to see what you came up with.

The chain tensioning (rather, the lack of it) is cool, too. How often did you have to change out chains on your 08 robot, and how loose did they get before you changed them? It seems like a great set up if they don't loosen up too incredibly fast. Also, are those custom one piece sprockets on the wheels?

Re: pic: 1503's Off-Season Project
 

I like how organized everything is, even on a congested electronics board.

I also like how the 80/20 'standoffs' are tapped for bolts for easy attachment of the outer side rails. Even better is that these 80/20 pieces could easily serve as chain tensioner mounts for a light-weight chain tensioner, should the design not have an auto-tension system.

Only criticism (and it's small!): I don't think it has enough ground clearance to traverse an elevated field component, nor is this particular design versatile enough to easily change a component to allow it to.

Great work!