Re: Drivetrains in Ultimate Ascent
 

How did you like VEXpro's wheels? We considered buying some wheels from them (not these), but decided not to because they are a new design and were never used before.
To be honest I really like some of their designs but we didn't have the courage to use them.

Re: Drivetrains in Ultimate Ascent
 

1014 is using six (4") wheel drive, with two omni wheels at the front (as determined by where discs are released) and two pairs of traction wheels, one pair in the middle and one in the back back. With tougbox mini at a 12.75:1 ratio. It is not fast but is very maneuverable and has good pushing power. No drop center. The omni wheels allow the robot to turn almost in place.

Re: Drivetrains in Ultimate Ascent
 

We now sell mecanum roller kits for those teams who wish to swap out used rollers:
http://www.vexrobotics.com/vexpro/wh...um-wheels.html

Are there any other parts you wanted to be able to replace? I think everything else is pretty modular.

-John

Re: Drivetrains in Ultimate Ascent
 

We're running 4WD WCD, direct-driven via VexPro single speed gearboxes and a 2nd VexPro gear stage to 4" AM Performance wheels. Can't remember what the final ratio is, but the speed is roughly 11.6ft/s before losses. The wheelbase is 30" wide x 18.5" long. Center of Gravity is biased 4" forward of front/rear center, and is nearly perfectly balanced left/right. It took us 1.5 weeks to fab it, and most of that was waiting to figure out what the frame would look like due to climbing and/or floor pickup. It weighs only 24.5 lbs and cost less than the kitbot because we made everything in-house.

Man does it fly too.

Re: Drivetrains in Ultimate Ascent
 

They're actually quite nice and are very, very grippy. Versa hubs are great too because they are very light weight and small. I encourage you to try the ones you considered for next season or later this season.

Re: Drivetrains in Ultimate Ascent
 

I will have a second look. Thanks

Re: Drivetrains in Ultimate Ascent
 

John, This is exactly what we wanted, nice and cheap to be able to replace the rollers like on the AM versions. Your team at vex has put out some great products and a see a bright future for you guys. Keep it up!

Re: Drivetrains in Ultimate Ascent
 

This is the second year in a row we are using Brecoflex treads. We are still debating whether to use treaded belts or smooth belts during competition, though.

Re: Drivetrains in Ultimate Ascent
 

We're running VersaWheels with Vex single speed / single stage gearboxes. Gearbox is chained to the wheels (32:16). That gives us a theoretical speed of 8.7 ft/s, which is the slowest we've geared since I started.

We decided that we had enough on our plates without doing anything fancy on the drive. With the chain reduction, we were able to to keep gearing it slower until we could spin the tires.

VersaWheels + single stage is just about as simple, cheap, and as light as it gets. We like it.

Re: Drivetrains in Ultimate Ascent
 

449 is running AM mecanums directly driven off of Toughbox Minis. Our entire robot doesn't have a spec of chains or belts.

Re: Drivetrains in Ultimate Ascent
 

What product are you using from them? A belt with a certain type of backing? or something else? I am quite intrigued by this brecoflex brand and its products.

Re: Drivetrains in Ultimate Ascent
 

1648 is using a wide 4wd with the nice Vexpro traction wheels and custom black roughtop tread. I love these wheels, they have so much traction that we ended up pulling carpet fibers out of our wheels. The traction was too much for our old carpet (talk about burnin' rubber)! We're also using the Toughbox mini's with a custom ratio (can't remember off the top of my head) with some sprocket work (15T on gearboxes, 22T on wheels) to get ~9 fps using JVN's calculator.

Re: Drivetrains in Ultimate Ascent
 

We'll see if the build lead for 422 comes out of the woodwork for this discussion, but I'll give you the spiel that you'll probably hear if you stop by the pit:

The drive train is quite the venture for 422, being the first non direct kit or kit-modified drive train system in years. There are a lot of things that were learned ("Hey, maybe we should be a little more gentle when welding" or "Hey, maybe our bearing blocks shouldn't be 1/12 of the robot weight") It's a 6WD "West Coast Inspired" drive system with 6-inch AndyMark performance Wheels lovingly covered in Blue Nitrile, feeding into a full VEXpro system of sprocket, chain, the single reduction gearbox, and 2 CIMs and 1 mini CIM on each side.

The numbers you're probably looking for:
15.17 fps, operating at 90% system efficiency on a total gear reduction of 8.25:1, creating what he calls a "friction limited system," a term I can't remember because I haven't slept in 30 hours. I think the idea is that as long as 422 initiates the contact, the other team is probably in for a bad time.

Now obviously a 6 motor drive train is not a battery's best friend (our new battery chargers are!), but 422 can rev up their shooter while driving (taking shots while moving isn't an ideal situation strategically or mechanically). I imagine the team will learn a lot this year, as they already have in building it. The drive team is just itching for Week 3 to come so they can pull it out of the bag and drive it around some more.

I didn't put a hand on a tool for this, that's just the readout they gave me to make the video.

Re: Drivetrains in Ultimate Ascent
 

The term "friction-limited" refers to the fact that the wheels will slip before the motors will stall, due to the amount of torque available.

Re: Drivetrains in Ultimate Ascent
 

We're using VexPro mecanums direct driven off of toughbox minis, with drop-down, geared-down 2" Colsons for anticipated pushing matches.