pic: 114: How we roll

[CraigHickman]

[cdm-description=photo]28091[/cdm-description]

[JoelP]

Single bolt tensioner system? Sounds interesting, how'd you do that? and what's the CoF of that nitrile stuff?

[sanddrag]

I like the blue roughtop stuff. We use it. Drives pretty nice. And about 45 matches worth of driving and it is holdng up just fine. Not even close to getting worn out.

Just curious, why did you chose to go to dead axles? (or so it appears).

[CrosbyAR]

where did you get that blue nitrile tread?

-Alex

[Rich Ross]

I'd like to know the CoF on that too. Any chance on a paper with the gearbox? Nice job on a sweet drive.

[Lil' Lavery]

Nitrile rough-top has essentially equivalent CoF to rubber rough-top, both about 1.3. 116 purchased our nitrile from McMaster, and I'd assume 114 did as well (only source I know of).

[robostangs548]

Rollin of fo's thats totally sick baller yo! Are they chrome? Next year we are thinking of getting anything that can be chrome dipped, chrome dipped. So we can have a "bling bling" robot..... We are also working on a ball bearing spinner idea.. We will tell you how that goes....

[ChrisMcK2186]

impressive, my team needs to learn how to build a drive train.

Chris

[CraigHickman]

Single bolt tensioner system? Sounds interesting, how'd you do that?
Our outer shafts are mounted in two bearing blocks inside a milled out pocket in the 2x1 frame bars, and the bearing blocks are linked via a plate on standoffs. From a plate at the front of the drivetrain, a bolt goes back to the linking plate, and can be tightened to pull the chain. Look here: http://www.chiefdelphi.com/media/photos/27585
You can kinda see the tensioner at the bottom corner.

Just curious, why did you chose to go to dead axles? (or so it appears).

The axles are live, with an eighth inch key in them. They sit in bearing blocks that are pulled to tension the sytem.

where did you get that blue nitrile tread?

McMaster. It's blue nitrile, food grade conveyor. We love the stuff.

Any chance on a paper with the gearbox? Nice job on a sweet drive.

I'm not too good at making papers. However, these transmissions may soon be sold from Trossen Robotics, in a partnership with Outback Manufacturing. Keep an eye out.

[Lil' Lavery]

McMaster. It's blue nitrile, food grade conveyor. We love the stuff.

It's actually not, just on the same page as the food grade conveyors. ;) The nitrile is incline belting.

[CraigHickman]

It's actually not, just on the same page as the food grade conveyors. ;) The nitrile is incline belting.

Bah, same difference. We love INCLINE BELTING then...

But yeah, it only slightly wore down, and only on the middle wheels. I have a feeling the wear was because of our ability to score extremely well, and so we were targeted with heavy defense the whole time...

[=Martin=Taylor=]

How often did you use high gear?

[Otaku]

Having 114 on our Alliance at Davis was awesome, though. 675 (us) and 2159 (Robopirates) played Defense while Eaglestrike had fun with the rack.

[CraigHickman]

How often did you use high gear?

Our driver didn't use it nearly as much as he could have. However, there were a couple notable sprints where it came in handy. I'm working on an idea to make the driver take advantage of it more next year.

[JoelP]

Just a few more questions,
Whats the weight of the gearbox alone?
Whats the weight of the entire drive base (including wheels, chain, gearboxes, motors, electronics)?
Why did you choose to go live axle without the benefit of being able to quickly change wheels (your outer side plate looks welded on)?

Thanks!

[CraigHickman]

Just a few more questions,
Whats the weight of the gearbox alone?
Whats the weight of the entire drive base (including wheels, chain, gearboxes, motors, electronics)?
Why did you choose to go live axle without the benefit of being able to quickly change wheels (your outer side plate looks welded on)?

Thanks!

Weight of the gearbox alone: 9 pounds with motors and pneumatics.
Weight of the entire drive base: somewhere around 40 pounds.
We have the ability to pull off that outer bar by undoing 4 bolts (you can't see them in this shot), and then it's simple to pull and swap wheels, gearboxes, and wheel modules. It was really a great system, mostly because I never needed to maintenance it.

[pakratt1991]

I had my doubts as to if you guys could get up on our platforms with your small wheels...
but I must say that in Davis your drive train REALLY proved itself to me. it got right up and your drive team was excellent, only needing a few seconds to do it :-)
Plus, those blue wheels kind of grew on me ;)

[AdamHeard]

is it any coinidence that you, 604, 254 and 968 all chose 4" wheels the same year? I know 254 has talked with 604 about wheels before, have you as well?

[CraigHickman]

Our wheels are done in an entirely different style than 254/968. And we don't really communicate, so no relation. Theirs is a two piece bolt together setup, where ours are a one piece sold object. In the past I've noticed less trouble with our design over the two piece.

[rachal]

1072 would like to say that they like the way 114 rolls :)

[redbarron]

The four inch wheels are nice. We like em so much we used 8 of them.:D The one thing I would have changed this year is the tread its done fine on traction but we have had to change them every regional due to them wearing down. But I was just wondering what the speeds of that tranny are. Nice Job too. Good luck

[Gabe]

is it any coinidence that you, 604, 254 and 968 all chose 4" wheels the same year? I know 254 has talked with 604 about wheels before, have you as well?
Just coincidence. We used 4" wheels this year because it acted like another gear reduction to go in tandem with our custom transmission this year. I would even venture to say that this is the same reason why 114, 254, and 968 had 4" wheels this year.

[Cory]

Just coincidence. We used 4" wheels this year because it acted like another gear reduction to go in tandem with our custom transmission this year. I would ever venture to say that this is the same reason why 114, 254, and 968 had 4" wheels this year.

yup... 4" wheels=much smaller initial reduction needed for the same speed=smaller gearbox=less weight.

[Joel J]

Nitrile rough-top has essentially equivalent CoF to rubber rough-top, both about 1.3. 116 purchased our nitrile from McMaster, and I'd assume 114 did as well (only source I know of).
Woah.. did you test to verify that?

Nitrile isn't as grippy as the SBR roughtop, as far as I can remember. In fact, there is a noticeable different upon inspecting both of them.

[114Klutz]

yup... 4" wheels=much smaller initial reduction needed for the same speed=smaller gearbox=less weight.

Yup. While the 4 inch wheels may have been a disadvantage when ramping, we felt that the weight gained by needing to reduce let was worth it.

The gearbox was an excellent, lightweight design. Next year, it will be even better, as Outback has talked to us about sponsorship. Issues this year will be worked out - one side worked perfectly, the other side shifted less reliably, resulting in the shift button acting as a right turn button.

With the aid of higher quality manufacturing - these issues should be taken care of.

As for Nitrile vs Rubber - Doing a few tests myself, rubber definitely seems more grippy. However, it is important to note, that on carpet, that much of the friction probably comes more from the little "bumps" on the roughtop locking themselves into the carpet, so the difference in COF may be considerably smaller then Nitrile vs Roughtop on a smooth surface.

Nitrile also seems far more durable, and longer lasting then rubber.

[CraigHickman]

Yeah, what he said. The one downside of custom wheels is cost. They are not cheap at all, because you have to make them out of a sold block for this design. However, I love them to death, and wouldn't trade them for any other kind of wheel. (however, we will be trading them for tank treads)

[AdamHeard]

Yeah, what he said. The one downside of custom wheels is cost. They are not cheap at all, because you have to make them out of a sold block for this design. However, I love them to death, and wouldn't trade them for any other kind of wheel. (however, we will be trading them for tank treads)

The Cost isn't that bad.

We can make 11 wheels out of a 12" piece (they are 1" wide) of 6" AL 6061 Rod ($145 at onlinemetals, similarly priced at a local metal supplier near us. In the end the material was donated anyway).

This comes out to less than $14.50 per wheel. That's not bad at all.

And since you have 4" wheels, it's even cheaper.

I can't wait to see the treads & shifter combo for real though.

[CraigHickman]

The Cost isn't that bad.

We can make 11 wheels out of a 12" piece (they are 1" wide) of 6" AL 6061 Rod ($145 at onlinemetals, similarly priced at a local metal supplier near us. In the end the material was donated anyway).

This comes out to less than $14.50 per wheel. That's not bad at all.

And since you have 4" wheels, it's even cheaper.

I can't wait to see the treads & shifter combo for real though.

The real cost comes from the machine time required to do this kind of wheel. With our design (which we've never had any issues with) it's a two op process. For our older 6 inch version, it was a 45 minute op. These wheels ain't cheap.

[EDIT] I've submitted a render of this system to be uploaded, highlighting our tensioner system. I highly suggest it to anyone thinking of doing a powerful 6 wheel next year, as it greatly decreases necessary maintenance.