pic: Problem with IFI Wheels

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#1

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During the build season this year, we had an issue with one of our IFI wheels on a 6 wheel drive train. The load on the aluminum side plate next to our sprocket was great enough to enlarge/deform the hole that the bearing sits in to 0.916". The outer diameter of the bearing is 0.875", which created a significant amount of wobble, which caused our chain to pop off once or twice, so we had to replace the wheel. The side plate opposite the sprocket was still intact. This happened on two separate occasions, first on the left front wheel, then the right rear wheel.

Has anyone else had issues like this? Any idea why it has happened to us?

#2

This happened to one of our drive wheels as well.
Seems like 5052 is not durable enough to take the load.
If IFI uses 6061 the wheel would work much better.

#3

How were the 3 screws around the bearing installed? Did you have the plastic washers between the screw heads, and the side plate?

#4

We did

#5

did you press a bearing into the sprocket itself?

#6

Since IFI produces a lot of their their aluminum products using CNC sheet metal fabrication machinery, it would not make sense to use 6061.

5052 (along with many of the 5xxx grades of aluminum) are much better suited for CNC turret/punch and bending machines than 6061, which is less malleable and more prone to cracking during cold rolling operations.

You can’t do much cold bending of 6061 and hope to achieve a bend radius equal to the thickness of the material, which is possible with several different 5xxx grade aluminum up to about 0.125" thick.

#7

Was the sprocket itself supported by a bearing or the axle? We’re using 6" IFI wheels and the flat AM aluminum sprockets. The sprockets have a bearing pressed into them and are bolted into the pattern on the IFI wheel (who woulda known they use the SAME bolt pattern?!). We also are using 1/8" plastic spacers between the wheel and sprocket on each of the 6 bolts. We’ve had some tug of wars and a bit of side bumping in matches but have yet to see a problem.

#8

Many, many thousands of IFI wheels have been sold. I have not heard of many complaints.

We’ve run probably 20 of the wheels without any problems at all. Many of them are multiple-season use.

I’m curious - were you using chain? If so, what gauge? Was the chain aligned properly from front to back - i.e. was it perfectly perpendicular to the shaft the wheel was running on, or was it pulling at an angle? How tight did you have it?

#9

We had the same problems in 2006 when we used them… After Florida that year we made nylon bearings that fit inside the wheel and spanned the entire width of the wheel. These worked well and we didnt have any more problems with the bearings buring the next 2 competitions.

We don’t use these wheels any more. For something like $60 each I would expect something far stronger, especially since it was designed for FRC teams.

Also, we found that the IFI sprockets were too thin for #35 chain which allowed for slop made it easier for the chain to pop off.

I have seen a number of teams that use these wheels and never have a problem, but i have also seen an equal number that have had problems with them.

#10

We’ve been using them for 2 years now and we have never had any problems with them. We have a practice robot that gets driven to death and we have one yet to fail. I personally like these wheels and I would use them again, IFI has a good product.

#11

Yes.

No, but this sounds like a very good idea, never thought about that. Maybe we will try this next year.

We were using #25 chain and it was aligned from front to back fairly well, and was pulling perpendicular to the shaft until the wheel started to deform. Once the wheel was wobbling though, the chain just popped right off. It did have a fairly good amount of tension in it as well.

#12

so wait…how many bearings did you have between the wheel and the axle? because with 2 bearings supporting it i don’t think this situation has a likelihood of occurring.

#13

We had two bearings - one on each side of the wheel itself, and yes, it did still happen. I think if we had had a 3rd bearing (like suggested above) on the sprocket itself, it could have solved our problem.

#14

It is a great idea, IT WILL KEEP THIS PROBLEM FROM EVER HAPPENING!!!

PLEASE TEAMS, PRESS A BEARING INTO THE SPROCKET!! (sorry for the caps I have to tell at least one team a year this, three this year)

I’m not suggesting that this might fix your problem, this WILL ELIMINATE THIS ISSUE (THIS IS NOT JUST FOR IFI WHEELS EITHER) skyways, AndyMark, colson…if you are bolting a plate sprocket to the wheel with some kind of spacer in between those two elements you should spend the dollar or whatever for the extra bearing for the sprocket. You might get lucky and nothing ever happens to your wheels, but just be cautious and throw that bearing in there, it is much cheaper than a new wheel.

#15

You must doing something wrong because we have been using them for the past two years and there industructable. Last year we competed in six competitions between first and off season events . also before the off season events we loged many hours of pratice time for the new drivers and not one failure.

#16

actually, because of the way that they are mounted, the bolt on sprockets (if left unsupported) can create a fairly large load on the wheels. this cyclical loading can cause major problems. this used to be the main cause of failure among the skyway wheels (see also: 1902’s 2006 exploding wheels), and while i’m not sure about the new kit wheels (they are much more robustly designed, as they have the bearings mounted farther apart), i’ve seen some pictures of failed wheels that look suspicious.

further more, if you at look both the sprockets available from ifi and am.biz, you’ll notice that they both are made to accept a 3/8 in bore flanged bearing.

#17

I noticed some similar wear on one of our IFI wheels from last year (the 6"x1" version), but it wasn’t worn that badly. Also, the wear seemed more like it came from the bearing turning against the wheel rather than being wollered out due to a deformed wheel plate.

…My theory is that the bearing wasn’t tightened down enuogh when our wheels were put together. The supporting evidence: when I was playing with one of the wheels that was laying around the shop, I noticed that one of the bearings was actually able to turn against the wheel! The screws seemed tight enough, but it was still able to turn. It’s my guess that the little white standoffs that go between the plate and the screws were too thick and didn’t allow the screws to clamp down tightly on the bearing.

I didn’t think much of it at the time, but it’s my guess that this is what happened to your wheels (though I may be wrong…). We’ve never had any deformation of any kind on our plates, and we were using the 6"x1" wheels last year (we were being pushed sideways for a good part of our matches, too).

#18

I wasn’t being specific as to the locations and knowing Richardmcc2 from his posts i know he is knowledgeable enough to not put one bearing on a wheel, it was just a quick check.

having the sprocket bolted to the wheel with both bearings in the wheel does create a high stress cantilever that i can see being enough to round out that whole, especially if there were any nonconcentric sprockets in the drive to pulse the chain from tight to really tight. putting a bearing in the sprocket should stop it because if relieves the cantilever

#19

They are not indestructible. We broke a wheel last year. and we had bering problems as well… PRESSING A BERING INTO THE SPROCKET WILL ELIMINATE this problem… it has worked for us…

#20

Well, he forgot to mention that the wheels were rotating at about 1000 rpm. To do this with #25 chain means that you could play a tune with all the tension we have on the chain. We put bearings in the sprockets and haven’t had any problems since.