pic: Dented IFI Wheel

[Drew Hopman]

We must have got a bad batch of them, because all 6 that we got are way out of tolerance. It took about 45 minutes to put each one together, bc the tread material was to short. At first it caused out chain to pop every time, because there was a high and low point from the chain caused by the sprocket holes not being drilled in the center. And I have also herd some horror stories from down south that the bearings tear apart after about a week and a half of use from more than one team….

[Chris]

To expand on what Tim said,

Our experiences were very positive, like they weren't perfect but they were darn good. With what I’ve learned this year I’d use them again in a second, I’d probably change a few things about the way I used them (such as sprocket placement, and hardware used) but we were pleased.

Another important point is we fought weight hard core this year, and there is no way Irrational would've ever made weight without the IFI wheels.
We have 12 on the robot.

8 in the 8 wheel drive system
4 in the ball lift system

Chalk up one to a statisfied customer,
Chris C.
Team 229

[Richard Wallace]

The designer of these wheels visited St. Louis back in December, serving as a technical advisor for our FVC demonstration event. He left me a sample 6 inch x 1.5 inch IFI wheel.

A few minutes ago I took that sample down to the CMM that we use to check parts here at Emerson's motor tech center. The results showed that the six hole pattern intended for mounting sprockets is concentric to the bearing hole within 0.004".

Each of the sprocket mount holes was 0.197-0.198 diameter (very nearly 5 millimeters). I'd conclude that the ideal sprocket screw size would be #10, or M5 if you wanted to use metric fasteners. Off center sprocket mounting could result from using smaller fasteners such as #8.

Of course, my CMM results are from a single sample. Close inspection of the holes indicates to me that they were punched, not drilled or bored; from this I guess that the sample was made using the punch tool that IFI subsequently used to make production parts.

[Tristan Lall]

Originally Posted by Drew Hopman

We must have got a bad batch of them, because all 6 that we got are way out of tolerance. It took about 45 minutes to put each one together, bc the tread material was to short. At first it caused out chain to pop every time, because there was a high and low point from the chain caused by the sprocket holes not being drilled in the center. And I have also herd some horror stories from down south that the bearings tear apart after about a week and a half of use from more than one team….

Did you assemble them with a shaft down the middle of the bearings? I don't know if that's in the instructions, but it is absolutely imperative that you do this. If you omit that step, your wheels will likely exhibit the misalignment problems described, and your bearings will be very unevenly loaded. The bearings themselves are relatively good quality (probably ABEC-3), and have never caused a problem for our team (either on IFI wheels, or on dozens of other applications over the years, where we used identical bearings).

My only real concern is with the press nuts; I realize that that's a concession to cheap manufacture, but I really hate the things. (They can, if overtightened, strip out.)

[Drew Hopman]

Originally Posted by Tristan Lall

Did you assemble them with a shaft down the middle of the bearings?

Yes, its not the wheel itself that seems to be the problem, it is the hole location for where the sprocket connects to the wheel, it seems as if they didnt do a good job making it centered, and causes the sprockets to wobble as much as 1/16" inch. If the wholes were correctly drilled then i beleieve we would be in a much better situation I am not trying to spark controversy, i am just expressing my personal experiance with the product.

[ChuckDickerson]

Originally Posted by Drew Hopman

Yes, its not the wheel itself that seems to be the problem, it is the hole location for where the sprocket connects to the wheel, it seems as if they didnt do a good job making it centered, and causes the sprockets to wobble as much as 1/16" inch. If the wholes were correctly drilled then i beleieve we would be in a much better situation I am not trying to spark controversy, i am just expressing my personal experiance with the product.

We used 6 of the 6"x2" wheels this year on our 6 wheel drive. As has been said these wheels are a bit expensive when you add up the wheels, separate tread, and sprockets, however, as has also been said they are super strong and super light and have great traction. I know our team couldn't make any wheels ourselves as strong and light any cheaper. I also don't know of any other off the shelf wheels as strong and light so pretty much I don't think you can beat these wheels. As to the manufacturing "defects" we noticed this as well, however, the holes are not drilled (technically punched) off center. What we found was that the holes that attach the sprockets to the side plate of the wheel are just a bit over-sized for the #10 screws that come with the wheels which allows for the sprocket to be bolted up off center. It was pretty much impossible to align the sprockets by hand so we overcame this minor problem by making an alignment tool. It works sort of like a clutch alignment tool and is nothing more than a piece of aluminum round stock turned down to the inside diameter of the sprocket and then turned down again to the ID of the bearings (3/8") to allow all the "centers" to be held in place as you bolt the sprocket to the side plates of the wheel. It still wasn't perfect but it was close enough to work fine. A second thing we noticed was that the holes were similarly over-sized for the two screws that hold the bearing retainers in place and thus the bearing retainers may (and probably will) bolt on a little off center. While this in no way effects the wheels operation it causes an optical illusion if you look down center of the wheel bearings making you think the sprocket is possibly more off center than it really is. Just pointing out our observations.

I really like the new IFI wheels. It would be great if they could lower the price by about half by next year. They were new and expensive this year but maybe by next year they can produce them in enough volume that the price will come down. I would dearly love to see these included in the KoP next year. Like I mentioned before in another thread, it would really be nice if FIRST would ditch the wheelchair wheels next year and include vouchers or something for 2 or 4 IFI wheels in whatever size you want. Sort of like they do with Bimba for the three air cylinders. If you want more than the 2 or 4 included in the KoP then you can buy them.