pic: Easy to make mecanum wheels

[BrianBSL]

Originally Posted by mechanicalbrain

We can bend plates of metal. Also I'm not looking at rubber, I'm looking at plastic or thin metal tread. Even if it doesn't terribly simplify the process I think a tread has certain other benefits when it comes to stability and climbing stairs.

I'm no ME, but I doubt you can bend the size metal that you need to make those plates out of (and not have them bend) with a regular manual break. I'd guess theres some pretty big loads, as you are supporting a roller that is supporting a significant amount of the robot's weight on it.

[sanddrag]

Well, I am becoming an ME so I'll take a shot at this one. We don't have a manual brake but I've bent 1/8" aluminum (and steel for that matter) quite nicely and fairly easily with a good mini-sledge and a vice. I think 1/8" would absolutely be sufficient for this, and you could probably get away with .090"

[mechanicalbrain]

Originally Posted by BrianBSL

I'm no ME, but I doubt you can bend the size metal that you need to make those plates out of (and not have them bend) with a regular manual break. I'd guess theres some pretty big loads, as you are supporting a roller that is supporting a significant amount of the robot's weight on it.

well the weight is distributed evenly along the length of all the touching rollers on both treads on each side, but yeah they would be adequately thick.

[ahecht]

Again, 190's wheels were slightly different than your treads, but our original aluminum supports bent with normal use (I don't remember the thickness, but they were at least 1/8") and we had to upgrade to steel.

Oh, and be careful bending metal on a vice. If you form a sharp corner, you will be losing a significant amount of strength.

[mechanicalbrain]

Originally Posted by ahecht

Again, 190's wheels were slightly different than your treads, but our original aluminum supports bent with normal use (I don't remember the thickness, but they were at least 1/8") and we had to upgrade to steel.

Oh, and be careful bending metal on a vice. If you form a sharp corner, you will be losing a significant amount of strength.

So I take two pieces bent toward each other to make a tent type shape... Yeah you always protect whatever you stick in a vice! I use scrap Balsa wood (1/4") as a buffer of choice!

[EricH]

I have three questions.
One, how are you going to keep from bouncing? You're driving along, and the roller edges hit the carpet coming around a 90 degree or so turn. Either you bounce, or you shatter the roller. Or maybe you shatter something else...

Two, how are you going to keep the rollers on? I mean, you can't just stick an axle through and say "stay" and have them stay on the axle. You need something hard on the outside, but how do you do that and not have to replace the whole tread?

Three, how much weight will this have? If it's too heavy, you might consider just wrapping the whole thing around a wheel for less weight.

[mechanicalbrain]

Originally Posted by EricH

I have three questions.
One, how are you going to keep from bouncing? You're driving along, and the roller edges hit the carpet coming around a 90 degree or so turn. Either you bounce, or you shatter the roller. Or maybe you shatter something else...

Two, how are you going to keep the rollers on? I mean, you can't just stick an axle through and say "stay" and have them stay on the axle. You need something hard on the outside, but how do you do that and not have to replace the whole tread?

Three, how much weight will this have? If it's too heavy, you might consider just wrapping the whole thing around a wheel for less weight.

I dont think this would bounce more then a tread and i don't think it would necisarily break. Look at most robots, none have suspension yet they arent (always) falling apart. Since i haven't tested it I can't speak to the reality of this answer.

I was thinking of using faerie dust. Agian this is me using AutoCAD agian after two years. No i intend a central shaft or even two triangle mounting plates on either side with a central core.

Well.... this idea hasn't been built yet, but... take an average tread design and add 2-3 pounds.

[EricH]

Originally Posted by mechanicalbrain

I dont think this would bounce more then a tread

When you consider that normal treads don't really bounce, but mecanum wheels might in a spin, and you'd get full mecanum effect... but we'll see once you get a set built and tested. You've got 3 months...after which point they need to be in testing or you won't be able to convince your team to do it this year.

Oh, and for mounting the rollers, you may want to twist the supports so the tread will actually move over tread-suppporting rollers without tearing something. And for roller axles, just make sure you can get the rollers off when you want to but not when you don't want to.

[mechanicalbrain]

Originally Posted by EricH

When you consider that normal treads don't really bounce, but mecanum wheels might in a spin, and you'd get full mecanum effect... but we'll see once you get a set built and tested. You've got 3 months...after which point they need to be in testing or you won't be able to convince your team to do it this year.

Oh, and for mounting the rollers, you may want to twist the supports so the tread will actually move over tread-suppporting rollers without tearing something. And for roller axles, just make sure you can get the rollers off when you want to but not when you don't want to.

No no no! this is like on my "over the summer to play with" list. You probably won't see this this year.

Also I have no intent on using anything but a hard (probably plastic) jointed tread. Until i find a place that can supply me with adequate tread this will not become anything more than a prototype (I can get some small tread for hobby robots but thats it so far)