pic: 296's Tri-Star Wheel
 

Re: pic: 296's Tri-Star Wheel
 

Pretty cool!
How much does it weigh?

JVN

Re: pic: 296's Tri-Star Wheel
 

Looks like someone has been watching too many epesodes of ducktales

Re: pic: 296's Tri-Star Wheel
 

Nice - using that to get on the platform?

Re: pic: 296's Tri-Star Wheel
 

we thought about doing something like that but we decided with something else. I would like to know the weight to cause with those gears kinda looks heavy

Re: pic: 296's Tri-Star Wheel
 

wow looks really cool, like ryan said we had considered doing something to that effect..

there are a lot of cool applications to a wheel like that later too...

like mayb being able to climb up a full flight of stairs

Dan

Re: pic: 296's Tri-Star Wheel
 

well i sure wish our team had enough enginuity to do that. it would take us the whole 6 weeks just to do the wheel and theyd still look like crap. we just hope that the pnuematic wheels being 2wice as tall as the platform and 4 wheel drive will be enough.

Re: pic: 296's Tri-Star Wheel
 

us too. we got a bunch of sponsers in the last week. too late. cuz we made our design to be as cheap as possible. due to lack of funding at the designing stage. the money's kinda going into our stomachs now.
is it hard to turn with those? unless you have casters or transwheels on the back. i somehow doubt youll use casters tho.

Re: pic: 296's Tri-Star Wheel
 

How many Tri-Star wheels are you useing?

Re: pic: 296's Tri-Star Wheel
 

Not to be nit-picky or even discriminatory, but I'd imagine a team like your's would be able to machine that a lot better. Personally, to me, it looks like the edges could of been done a lot better, but I don't know if you intended it to be like that.

I'm sure a lot of teams thought about doing this at one point or another, I know my team did in particular. But we realized that you can get up the stairs perfectly fine with 6 12" pnuematic tires (each at a different height to compensate each other of course).

Re: pic: 296's Tri-Star Wheel
 

You don't even need 6 pnuematic wheels. You can get up the step with 4 12" pnuematics.

Re: pic: 296's Tri-Star Wheel
 

Yeah we realize that too, but we found that our configuration actually got up more easily with 6 12" tires. That, and we use 6 12" tires every year and didn't want to break tradition :)

I might be thinking of the 8" pneumatic tires that came with the kit, not the 12" ones. Because I remember us trying to larger tires that came in the kit and with our drive train it actually went up worse.

Re: pic: 296's Tri-Star Wheel
 

you can also get up with 6 6" pneumatic tires and a 9" piece of aluminum on a rubber band.

Re: pic: 296's Tri-Star Wheel
 

That's machined badly?!?! In that case, our robot is the embodiment of bad construction. Much of it is hacksawed lengths of various strips or pieces of bent sheet metal or aluminum extrusion. flat metal surfaces epoxied to plastic, motors mounted to diamond plate just because thats what we had lying around... That tri-star wheels is god-like compared to ours.

Seriously, your so called quality of machining isn't terribly important, in my opinion. Not every piece has to be CNC cut and then TIG welded. In many engineering jobs, there isn't the time or the need for good looks and custom made stuff.

Re: pic: 296's Tri-Star Wheel
 

agreed.
NOTHING on our robot is welded.. yet? maybe if we have time we might reinforce. cnc? um... yeah. we have one. we used it for one piece on our robot? maybe...
its all about how accurate your eye is on our robot.. and alot of washers :D

Re: pic: 296's Tri-Star Wheel
 

You're misunderstanding my statement. I didn't say it was machined badly, I'm saying a team like that could of machined it BETTER. I'm talking mainly about the edges, personally if it was me, I would of made it more of a straight edge as opposed to being bumpy such as theres. I'm not sure if it's meant to be like that, but seeing as how big the tires are, and what they're trying to do, I'm just offering my opinion.

Re: pic: 296's Tri-Star Wheel
 

I noticed that all the tri-wheels have the same "bumpy edges" and I believe they were designed like that. The sides are all the same too...also implying the general design.

Re: pic: 296's Tri-Star Wheel
 

Who the heck cares how well they machined it? jeez... dont you have something on your robot to work on rather than nitpicking someone else's machining? I think it looks pretty darn good myself, and I cant wait to see it in action. Good job 296!

P.S. If the parts I made looked as good as those, I would be very happy :)

Cory

Re: pic: 296's Tri-Star Wheel
 

I'm not affiliated with their team in anyw ay, but I'd guess the reason for the edges is to give that gear a little extra support all around. The edges bow out slightly around the axle and then go back in probably to save weight.

So now for some questions: CNC milled or waterjet? To me it looks like it was cut with a waterjet. Also- did you get the idea for the curve from a stress analyzation program? We had an engineer on our team once who had the software and allowed us to save all kinds of weight.

Anyway, great looking part and keep up the great machining.

Re: pic: 296's Tri-Star Wheel
 

Sorry for not replying sooner - I've been at robotics all weekend until now.

Those wheels weigh ten pounds each, and we are using two in the front, with two six-inch wheels in the back.

We actually designed the sides of the plates that way (not straight) , only because we found that the metal would touch the corner of the step while we were climbing it. It's not a curve, just either two or three seperate straight sides that meet to form corners. We got the plates, shafts and wheel hubs machined professionally (I'm not sure what method they used, but the plates look pretty sweet up close).

The turning is very good, considering all eight of our wheels are made of neoprene rubber.

Hope that answers all your questions.

Re: pic: 296's Tri-Star Wheel
 

That is machined very well. Im not sure what that guy is thinking.:) Anway have you tested the wheels yet? Also, why did you guys go for the gears instead of chains? The weight probably would have been cut down and it would have simplified the whole process.

Re: pic: 296's Tri-Star Wheel
 

I don't see where we could have used chains... seems like it would be a pain to tension them.

We did test the wheels, and they are performing beautifully, except that we haven't yet put delrin sliders or something else on the bottom of the 'bot, and so we can't get more than halfway up the step for now.

Re: pic: 296's Tri-Star Wheel
 

The chains would serve the same purpose as the gears. The only reason what I could think of using them is the weight.

Re: pic: 296's Tri-Star Wheel
 

It lookes to me like the "bumps" are to provide what we here in the aircraft biz call ED or edge distance. That is the distance from the center of a hole to the nearest edge of the part. If a hole is too near an edge it lowers the strength of the part tremendously. In general, we use a minimum ED of 1.5 times the hole diameter, though I've been noticing lately that EDs of 1 are common in commercial products. If the bumps weren't there, the shafts supporting the small gears would be hanging out in space, either that or the wheel would be even heavier.

I think the design has been nicely optimized and well executed. If there were big ugly burrs hanging off the edge or chatter marks or the edges wandered like they had been cut with a hack saw then pras870 might have a point, but as it is I don't think so. It seems pretty obvious to me that those bumps were planned and needed to be just where they are. It is a professional looking job, good work 296!