make vs. buy wheels

What are advantages/disadvantages of making your own wheels. I was looking through old pictures, and lots of teams make their own. How does weight compare to the KOP wheels. Thanks :smiley:

The advantage of making one’s own wheels comes in the form of having the exact wheel you want–diameter, width, tread (or tread attachment), and method of drive (dead axle, live axle (keyed or hex), etc.). The disadvantage of making your own is that it takes time (both human and machine) and effort.

On the flip side, COTS wheels are readily available and require little to no machining time. You may not get exactly what you want, though.

I’ve been involved in FRC for five seasons now, and the teams I’ve worked with have never used or needed a custom-made wheel for drive purposes; we’ve always focused any machining efforts on a manipulator. (And looking at some of the manipulators, I shudder to think what our wheels would look like! :eek: ) Of course, that’s what suits us; we tend to have a tolerable amount of money and not so much fabrication ability. You, on the other hand, may have no money but an old metal shop with a lot of suitable material; if that’s the case, you’d probably want to look into it.

It all comes down (if we focus solely on the robot for a second) to using your available resources to make your robot as effective on the field as it can be.

COTS wheels suppliers make wheels that are just as good, but maybe not to your exact specifications. Often times, we had to adjust our shafts/frame to fit the wheels instead.
However, this past year, we machined our own wheels.
Was there an advantage? I would say no.
It was cool looking though.
We will continue to make wheels simply because it gives a greater opportunity for our students to have ownership and use CAD to create what they want.

I agree with waialua. making your own wheels usually doesn’t supply much of an advantage on paper.

However, wheels are something that aren’t particularly hard to machine. Making your own can give newer students a chance at machining something that can’t be screwed up as easily as machining say- a gearbox.

Making your own wheels also just adds a coolness factor to your robot. It is something that you built and distinguishes your robot even further from everyone else’s.

Our team has been using 1in thick plywood wood wheels for a very long time and have had no problems with them. There also very easy to manufacture, we have all six of them done by day 2 of build season. It also allows tread to be attached with ease all we do is use contact cement and then use wood screws. We have never lost a tread or cracked a wheel. So if u want a custom wheel that you can make easily use wood like our mentor says wood is good. If you want to know the exact process just ask.:smiley:

Depending on what equipment you have, it can be very costly and take large amounts of time to machine anything. My team doesn’t have a mill or any other type of machining equipment. We either have to have a mentor machine custom things, or hope that a machine shop will donate machining. Thus, we don’t have many machined parts on our bots.

If you have anything machined, you have to make spares as well. If you don’t and one of your parts breaks, you’re not in a good position.

At the same time, not having particularly scarce COTS parts you put on the robot would be a bad call as well. Kit wheel? Someone probably has them. N-tooth IFI sprocket? You might get lucky. Part Made By A Local Company When You’re Competing 800 Miles Away? Bring three.

This past year, we used two piece beadlock wheels to clamp the tread on. It was much easier than riveting and found it to be advantageous for changing tread. It was worth it for us to machine our own, but next year, with the new AM two piece beadlock wheels, there won’t be much of an advantage for us to make our own. Andy has us sold on it.:stuck_out_tongue:

the point about cost to machine own is in large part a factor. aluminum plates that we ordered and the time it takes to machine is much much more and much much longer. Teams will factor in their cost vs performance vs learning experience.
On another note, thanks for the update on the new andymark wheel. We may go with that on our prototype base.

WOOD IS GOOD (use plywood)!!! light and strong substitute for aluminum. Backed by team 188 whose been using it for many many years with out fail. Also is relatively cheap i believe and easy to manufacture our team gets the new students to do them so they learn how to use a lath and drill press. MAX 2 days to make 8 wheels easy.

Time is the only thing that teams can never acquire more of during the build season. Everything else - money, materials, machining resources, mentors, Mountain Dew - all have the potential of acquiring more of them.

As such, during your six weeks, is it better for you to purchase COTS wheels with no or minimal modifications and move on to more important tasks - like the manipulator which actually does the scoring - or spend days machining wheels which more or less do the same function as COTS ones?

Now if you have sufficient resources at your disposal, and it is decided that machining/fabricating custom wheels will not detract from your ability to create an awesome robot, then by all means go for it. Otherwise, there’s bigger fish to fry during the build season.

Remember: custom does not necessarily mean better. Engineering is just as much about optimizing time/ease of assembly and minimizing costs as it is about actually designing stuff.

Our first year wheels were made out of wood. We couldn’t afford anything else and didn’t have much time. They worked OK, except for the really cheap “rubber” mat tread we got at Home Depot or somewhere. It was a dual-wheel setup, with the sprocket sandwiched in between the wheels, live axle with outboard bearings. They were made from glued 1 x 4 pine boards (the maximum size wood allowed that year) sawed out on a band saw.

That was back in the days when the drill motors and transmissions still came with the plastic drill housing/handle. We just sawed off the handle and used the cordless drill case as the motor mount :smiley:

The only real advantage to custom wheels is the coolness factor, and important factor yes, but can be overlooked if needed. I’d say try making them in the off season and if you like them, have time and the resourses then go for it. Me, I am a proud supporter of the KOP wheels, tough, great grip, just a little tricky to mount.

There are many advantages besides getting looking cool. You can usually save a good deal of weight, along with getting the exact diameter, width and mounting options you want.

I’ve preferred custom wheels for a while, but, depending on the weight, the new AndyMark wheels may sway me.

Wood vs. Metal and also what is the best material to use for traction. Website please. Thanks :smiley:

Metal doesn’t give you splinters if it’s worn down too much or beaten up… but wood is cheaper. Anyone try plastic at all?

Lots of teams use blue nitrile tread (I think McMaster carries it), though others prefer roughtop or wedgetop tread (not sure on where to get those). A little suggestion: use CD’s search feature, looking for “blue nitrile tread”, and you should find some websites.

The common tread people use on custom wheels (and on IFI and some andymark wheels) is sold as “incline conveyor belting” from mcmaster. There are two surface types, wedgetop and roughtop.

The wedgetop is just offered from mcmaster in gum rubber (but I’ve seen some teams, 188 in 2007, with black SBR rubber).

The roughtop is offered in many types, but is most commonly used in natural rubber (tan), SBR rubber (black) and Nitrile (blue). Nitrile seems to wear the best by far, although offering reduced friction. The natural rubber seems to be commonly used, but can wear very fast. I’ve seen very few teams use the black SBR roughtop, but it seems to be closer to the natural rubber in performance and wear.

We used the ‘Wedge Top’ belting in 2006 and it seemed to wear out pretty quick. I think in total we were forced to re-tread our wheels at least once a competition. Also, we’ve noticed that it dries out after 6-8 months which will end up reducing your traction.

We have used the black ‘Rough Top’ the past two years. It seems to hold up much better than the ‘Wedge Top’ does. Both years we were able to put about 15 hours of drive time, or roughly 415 matches, before the tread had to be changed on our practice robots. I don’t recommend letting your tread get to this point in competition. We change ours about once every competition.

Also, the ‘Rough Top’ doesn’t seem to dry out like the ‘Wedge Top’ does. Our 2007 competition robot has had the same tread on for the last 10+ months and it feels that same as when we cut it.

My favorite wheels have got to be the colson wheels (found here and a billion other places). They have lots of traction, they’re very thick, so as the tread wears down nothing needs to be replaced, they’re light, and they’re dirt cheap to boot. We used the 7/8" wide variety and they had plenty of traction.

Many people will say that the conveyor belting material offers more traction. I am dubious of this.

Although the conveyor belting material does have a higher coefficient of friction than the colsons, you must remember that it was designed to move food… Food usually isn’t dirty (I hope), and it also doesn’t offer much wear.

Colsons on the other hand were designed to be used as castors for heavy equipment. They are meant to work in dirty environments. As a result, Colson designed them to be resistant to dirt and wear slowly (they brag about this on their site).

We never had to change the wheels all season… But we did replace two of them with omnis since they offered too much traction :smiley:

Some teams buy pneumatic wheels and modify them to interface with AndyMark or IFI sprockets. 330 goes through several sets a season, just because they drive them so much. Figure 2 sets of pneumatic caster tires per season, for competition only, and a third set in the offseason. And that’s only the competition robot! Then again, that’s better than blue nitrile, which may have to be replaced once a competition at minimum.