6" Pneumatic Wheel Help/Suggestions for other wheels for an outdoors robot

[AndreaV]

It could use BOTH

Yes, it fits the 6" pneumatic plastic hub from AndyMark.

We lathed some excess off of ours to fit it into our shooter, I think the excess if for sprocket spacing. It lathes beautifully. Like 1334 we also scrapped the steel rims and inner tube, no pool noodle though. For a drive train I am sure you would want an inner tube.

Just a word of warning, the grey non marking wheels are just the black rubber wheels with a thin non marking layer on it, we noticed it starting to get rough after one shooter practice session. I am sure they would get torn up on concrete.

BTW last year if I recall correctly some teams didn't use a dropped center, and instead just adjusted the air in their wheels to get the desired results.

[GarrettF2395]

Another option would be to use 6" Colson wheels and cut a tread pattern into each wheel, similar to what team 25 and 103 use. I've that they hold up to abuse well. West Coast Products make these handy little press fit hubs to make life a little easier.
wcproducts.net/wcp-00052/
There is also a live axle version available.

[AndreaV]

Originally Posted by GarrettF2395

Another option would be to use 6" Colson wheels and cut a tread pattern into each wheel, similar to what team 25 and 103 use. I've that they hold up to abuse well. West Coast Products make these handy little press fit hubs to make life a little easier.
wcproducts.net/wcp-00052/
There is also a live axle version available.

Colsons do hold up to abuse, but if the robot is going over rough terrain it will transfer vibration to the chassis, and I am not sure how good it will be on grass or dirt. With the treads cut into them I am sure it will fling stuff all over the place as well. Great for concrete and indoor use though.

[MetalJacket]

Thanks for all of the advise everyone, after consideration, we have decided to go ahead and use the 8" pneumatic wheels; if however, we do decide to use 6", at least I now know how to do it . We will be posting pictures of this design once everything is finished, and hopefully some video of the cannon shooting.

[GarrettF2395]

Originally Posted by AndreaV

Colsons do hold up to abuse, but if the robot is going over rough terrain it will transfer vibration to the chassis, and I am not sure how good it will be on grass or dirt.
With the treads cut into them I am sure it will fling stuff all over the place as well. Great for concrete and indoor use though.

Very good point, it didn't occur to me that vibration would be a design factor but you are absolutely right.
Another good reason to stick with pneumatic wheels for this occasion.

Thanks for all of the advise everyone, after consideration, we have decided to go ahead and use the 8" pneumatic wheels;
if however, we do decide to use 6", at least I now know how to do it . We will be posting pictures of this design once everything is finished, and hopefully some video of the cannon shooting.

Glad to hear that you've come to a decision. One word of advice, make sure you lower your center wheel more than an average 6WD.
We used the AndyMark 8" pneumatic wheels in '12 and made the mistake of only doing an 1/8th inch drop. Our maneuverability and turning were absolutely horrific.
Maybe someone else can chime in with the correct numbers, but I think I've read that you want at least a 1/4 inch drop on your center wheel.

[MetalJacket]

Originally Posted by GarrettF2395

One word of advice, make sure you lower your center wheel more than an average 6WD.
We used the AndyMark 8" pneumatic wheels in '12 and made the mistake of only doing an 1/8th inch drop. Our maneuverability and turning were absolutely horrific.
Maybe someone else can chime in with the correct numbers, but I think I've read that you want at least a 1/4 inch drop on your center wheel.

Do you think that with the uneven wheel inflation mentioned in an earlier post (center wheel more inflated than outer) a 1/8" drop would work? Not that it's too hard to change in the model, just curious

[GarrettF2395]

Originally Posted by MetalJacket

Do you think that with the uneven wheel inflation mentioned in an earlier post (center wheel more inflated than outer) a 1/8" drop would work? Not that it's too hard to change in the model, just curious

We tried that and still didn't have a lot of success with our turning ability.
We eventually wrapped ducktape around a pair of our tires to decrease our traction, and that was enough to get us turning better.
Anyways, increase your drop for sure.
Also, get a pair of wheels to test with and check their compression at full PSI.
That ways, you've got some numbers to design with, instead of just going off of what others think is the proper drop.
Hope that helps!

[George C]

One way to experiment with centre drop is to mount your axles to small plates bolted to the chassis rather than direct to the chassis. Make an over size hole in the chassis to allow for vertical axle movement and then make up plates with different amounts of drop on the same bolt pattern. These go over the holes through the chassis. It's a good idea to label the plates with the amount of drop. You'll need them in sets of 4 - two for each axle. It doesn't have to be the centre axle that gets dropped. Raising one pair (either front or rear) of the outer axles does pretty much the same thing and can be easier - particularly if you're using direct drive. We didn't need them this past season put have made them in increments of 1/16 in the past.