What types of wheels have teams found to work best on pitcher like shooters. Also which sizes of wheels.
This is really something your team should experiment with. Use different motors, different gear ratios, wheels with different traction material and of different radii.
We got out Blue bane-bots wheels today and couldn’t be more pleased. They have an Incredible amount of grip on the game piece which means we need less compression to effectively shoot the basketballs.
Do you know what the maximum RPM rating for those wheels is?
I assume you got the maximum diameter.
For maximum ball grip, why did you select the FIRMEST 50A rubber instead of the SOFTEST 30A formula?
-RRLedford
Our team color is blue so we got the blue wheels, we got the 3 and 7/8 .5 key bore wheel .8 inches wide. 50 shore A is still incredibly soft, The other lead designer and I preferred durability over a little more grip, and they grip so well anyway that we don’t think it will be a problem. The Blue wheels are so grippy in fact, that you can press them into the wheel without applying anything other than normal force to the surface of the ball, and when you remove the wheel little flecks of the Orange paint come off the ball, anything gripper and you would be in danger of shredding both the ball and the wheel. We chose the roughly 4 inch diameter size because it worked nicely with our available reduction on the 500 series motors available, as well as positioning in the robot. These wheels are being used both as Intake and Launcher wheels, and we wanted both to be the same size so the robot has more uniform parts, and the 4 inch size allows us to most conveniently push the intake roller to the frame perimeter.
Our initial prototype we used our spare drive wheels from last season (4" x 1.5" Colson Performas) direct drive by a CIM. We like the grip they provided and how they handled the ball, but we weren’t getting the distance we wanted.
We switched to a 6" Kitbot wheel with the same compression and while we got the distance we wanted, we started to markup and damage the ball.
For the actual shooter we have 6" x 1.5" Colson Performas.
I think the most difficult thing for us right now is making sure that our wheel choice doesn’t destroy the balls. We are using the pneumatic tires from Andymark - the distance is amazing but we have to work on keeping them from shredding the tires.
For one of our prototypes we are using 2 kitbot wheels with a taction wheel in the middle (smaller diameter creating somewhat of a ‘U’ shape). We did notice that we were marking up the ball with this set up so we decided to literally cover all of it in duct tape…it worked! No more marking up the ball and to be honest, I do not think we lost any distance on the actual shot. I sort of looks like a drum now with a depression in the middle. Keeps the balls flying straight and consistent.
We will be making our own wheel. Aluminum “rim” with solid PVC endcaps. We will “tread” the wheel by pouring urethane into a 3D printed mold around the aluminum rim and endcaps. We will be using a Shore 70A urethane.
-Brando
Where do you get the urethane and what exactly does a person need to buy to do this?
Bruce
For us, urethane and silicone are purchased from a local distributor of Smooth On products in Boston. http://www.smooth-on.com/
You just need some basic framing supplies, wood, nails, screws and a vacuum pump to do it correctly. A lot of the videos on Smooth On’s site are pretty useful for beginners. The big thing will be the mold. I have access to a 3D printer so I am able to make life easier that way. You don’t need one though. You can just as easily use a piece of PVC pipe, or some other round object if you are molding tread around a wheel.
We’re going to mold in a V-shape which is why we will be using the 3D printed mold. However you can accomplish the same thing by using clay with the PVC pipe or other round piece.
If you are really interested in doing it feel free to PM me or do a couple searches on here. A couple teams have had great success doing this kind of stuff.
-Brando
Can you tell me what urethane product you are using. Read about some of them but it is very confusing. If you have had success with one of them could you please share?
THanks
Bruce
I’ve had great success with the MoldMax and Task series of materials in the past. The Task series is a urethane plastic, which won’t work for our application of tread, we want a urethane rubber. For that, we are either going to use the VytaFlex series or the PMC-770.
If you have to make the actual mold, I would definitely recommend any of the MoldMax-es. My general go-to is the MoldMax 30.
-Brando
In 2006 we prototyped a shooter using wheels similar to AM’s Pneumatic and could not find a way to make them play well with poof balls. It seems that any wheel with a texture to it will start to chunk the ball with too much compression or if it hits the wrong way. Try swapping in some 2010 kit wheels or 8" Colsons (going to be heavy) and see what kind of results those wheels get you.
The thing with Colsons at that size is that pocketing them out does become easier, which means you can start to get the weight down.
Brandon, what thickness of urethane have you found to work well?
Thanks
Bruce
Didn’t even thing about that, Brandon. Have any idea how much weight you could pull out of an 8" Colson? An 8 x 1.5" wheel weighs about 25oz which is a lot of weight if it’s up high. Think you could get it down to the sub 1lb range?
We used 8"X1" Colsons back in 2006. We didn’t take weight out of them back then, but pulling 10 oz. out doesnt seem out of the realm of possibility to me.
It will take time, but with a good plan I think its doable.
That is going to be something of an experiment for us as well. I think 0.250" would be a good starting point. Maybe more, maybe less depending on application. If this was a caster wheel supporting a lot of weight, you would want a harder rubber and a thinner layer. For a shooter wheel though, I think you will have more leeway.