pic: 1503's Off-Season Project

[Pat Fairbank]

Thanks, everyone, for the comments.

Originally Posted by sdcantrell56

How heavy is the entire thing without electronics and with electronics?

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.

Originally Posted by sdcantrell56

Are those the banebots wheels? If so how are they holding up and how is traction?

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.

Originally Posted by sdcantrell56

Does this drivetrain have the ability to climb ramps and if not would it be easy to modify it?

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.

Originally Posted by sdcantrell56

How are the chains tensioned?

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.

Originally Posted by M. Mellott

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?

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.

Originally Posted by Hachiban VIII

30 Shore A wheels!

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

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.

Originally Posted by RyanCahoon

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

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.

Originally Posted by RyanCahoon

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)?

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.

Originally Posted by Jonathan Norris

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.

Geez, all this talk of cookies, and yet nobody ever follows through...
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.

Originally Posted by AdamHeard

How easily can wheels be swapped out?

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.

Originally Posted by AdamHeard

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

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.