Which treads have an advantage?
 

At competitions teams had the exact same gearbox; but when a shoving match teams with treads won. I was wondering if anyone saw that also. And which tread is better Rough Top or Wedge Top?

Re: Which treads have an advantage?
 

I have seen both designs work effectively at pushing. Aka S.P.A.M. this year and Cyber Blue in 04. I personally like the rough top it's better for turning and still gets the power to the ground. I am not sure which cost more but I am pretty sure rough top is cheaper. Also if you don't have a big budget I would not recommend treads.

my two cents,
Drew D.
Tech tigers
team#1251

Re: Which treads have an advantage?
 

i'm not sure the company we get our threads from..but the best ones we found where the white ones... which cost around 200 bucks each...

those threads we used this year and in the past and they have great traction...

Re: Which treads have an advantage?
 

Roughtop vs. Wedgetop

I think they are about comparable when it comes to traction. I believe Roughtop has a little bit higher traction.

229 used Roughtop this year, for one simple reason: wear characteristics.
The Roughtop tread wears down much nicer than the Wedgetop while providing comparable (if not better) traction.
It is mostly a matter of preference. Some teams swear by one, some swear by the other.

Re: Which treads have an advantage?
 

roughtop and wedgetop are incline conveyor belting--which means they aren't suitable for use as treads, but rather as a traction material on wheels (You can get roughtop from Brecoflex, though). I think they're both pretty evenly priced, and it just comes down to personal preference.

Re: Which treads have an advantage?
 

I've seen people say this so many times that I just can't take it any more. Unless you are talking about team shirts or forum discussions there aren't any threads to be discussed here. The matter at hand is treads (like referring to tank tracks) and more specifically tread (singular) referring to the traction enhancing material attached to the surface of a wheel. Thank you.

Now for rough top versus wedgetop, I would second most everything said above. Also, I don't think anyone has done any real testing between the two to determine which is better so most of it is probably just hearsay.

The wedgetop one does seem to be more popular. It does seem though that wear seems to be directly proportional to ground pressure which is inversely proportional to width. On wheels with 1.125" wide wedgetop we experienced no detectable wear whatsoever on carpet over the course of practice and one regional. However teams with .75" wide wheels with wedgetop have been known to have lots of wear and have to replace the tread during a regional.

One question that came up between a few of us is which way to run the diamonds with wedgetop. Because the diamonds are not simply rotated squares, they have a long diagonal and a short diagonal. So, what are the differences between running the diamonds long diagonal parallel with the circumference line and running the diamonds with the long diagonal perpendicular to the circumference line? Does anyone know? In a way I doubt that anyone really does know or has tested both ways

Re: Which treads have an advantage?
 

I've been thinking about the Roughtop vs. Wedgetop debate for the past few days. I'd be really curious to see some concrete data on this. Is there anyone out there who'd be willing to do a few traction tests? It'd make for a simple but very useful whitepaper. It could suffice for a simple science fair project as well. My hypothesis is that they both provide similar traction. Nevertheless, there has to be some reason that certain people swear that one type or the other provides considerably better traction.

Re: Which treads have an advantage?
 

If you're talking about what I think you are, see Team 60's 2005 robot.

They cut their wedgetop so that the elongated side of the diamond was facing forward. I imagine they did it more for better wear characteristics than for better traction.

It takes a heck of a wide sheet to be able to do that though. Looking at McMaster's site, they only sell 18" width wedgetop, which isn't even enough to go around a 6" wheel.

Re: Which treads have an advantage?
 

I just did some tests just last week. Roughtop gives a better coefficient of friction, from what my tests show. We are getting ready to sell 4", 5", & 6" diameter wheels with replaceable treads through AndyMark.biz. Here are my preliminary results:

surface: FIRST field carpet
weight on tread: 25 lbs.
tread size: 4"x1.5"

Material: Urethane roughtop, 0.20 thick
Max pull force to begin movement: 28 lbs
coefficient of friction: 28/25 = 1.1

Material: SBR wedgetop, 0.25 thick
Max pull force to begin movement: 31 lbs
coefficient of friction: 31/25 = 1.2

Material: SBR roughtop, 0.25 thick
Max pull force to begin movement: 33 lbs
coefficient of friction: 33/25 = 1.3

We are going through a website upgrade, so these wheels are not shown yet. Here are some specifics of our "Traction Wheels":

4" dia x 1.3" wide tread - $46
5" dia x 1.8" wide tread - $50
6" dia x 1.8" wide tread - $54

All 3 sizes have these qualities:
3/4" bore w/ roller bearing
Molded nylon body w/ fiberglass reinforcement
aluminum drive hub with sprocket mounting holes
aluminum sprockets as optional parts (35 series)
Treads can be easily replaced with screws

Once the site gets updated, I will post a link. These wheels will be available in mid-November.

Andy B.

Re: Which treads have an advantage?
 

IBApril did a traction test a couple of years ago and posted a white paper on the results. Go here: http://www.chiefdelphi.com/forums/pa...le&paperid=120to see what she came up with.

Re: Which treads have an advantage?
 

Exactly. We found that putting the elongated side of the diamond "sideways" caused the tread to wear out much quicker. As for the supply for our tread, I am not sure, but the "wedgetop" tread seems to work well for our type of wheels.

Re: Which treads have an advantage?
 

I'm having trouble locating the " urethane roughtop" on the McMaster-Carr website, that Mr. Andy Baker reffered to above. I checked page 1091 of the online catalog, where the other two are located, but couldn't find this material. Anyone know where to find it?

Also, last year, our team found that our 4 outer wheels, which had SBR wedge-top material, had two much lateral traction (this was really evident when we turned, the robot would wobble and hop). So:

1)Would it seem logical to drop down to urethane roughtop on the outer wheels to reduce lateral traction?
2)Would SBR roughtop perhaps have less lateral traction than SBR wedgetop, although it has greater in-line traction?

Re: Which treads have an advantage?
 

We noticed the same. It was our first year using wheels with tread on them and the rough top SBR material gripped too much on the outer wheels and caused handling problems when turning, so we ended up replacing them with the harder nitrile rough top and life was much better. See attached pics...

So what is this urethane material Andy refers to? Is it the neoprene that McMaster sells?

Another question that has come up lately is why many teams are favoring the wider wheels - is it too reduce wear?

Re: Which treads have an advantage?
 

We used the SBR wedgetop last year, and we had to cut it by hand using an X-Acto knife and similar hand tools. When run through the bandsaw, it would basically act as a "brake" and stop the blade. How do you guys cut your wedgetop?

Re: Which treads have an advantage?
 

We tried cutting it on the bandsaw and the blade mostly just tried to suck it down/in. Then, we thought maybe we could turn it over for better results, but then it wouldn't slide on the saw table. So, we put it upside down (grippy side toward the table) and set it on top of a piece of paper on the table, and then it was able to slide easily and the saw cut it to perfection. It came out a perfect cut! Try using a fine blade meant for cutting metal so it doesn't catch the rubber and pull it down.