We have a shooter that uses 2 8" AM FIRST wheels with the standard urethane rubber treads on a rotating 55 degree LA turrent. We spin it up from 300 to 3K RPM using PID control of 2 FP 0673 (6:1) and 2 AM 9015 (4.64:1) motors. It works quite well but we keep tweaking the performance on a practice bot (typical engineers!).
I searched and did not find much discussion about using different wheel treads on an otherwise working shooter. Has anyone tried something like AM plaction wheels with wedge-top or rough-top tread? Does it help/hurt?
Sounds like way more motor than necessary. We are using a custom 6" diameter polycarbonate wheel with 10" polycarbonate flanges on the sides. We are spinning it with a single FP 0673 using a BB Cimulator and further reducing through a belt drive for a final ratio of about 4.1:1. We spin the wheel anywhere from ~2200 RPM for close up shots to ~3300 RPM to shoot from the barrier. We have no problems spinning up quickly and maintaining speed, nor shooting rapidly.
By the way, A PID is over kill for this application. The system has enough inertia that speed changes slowly (in the computer sense of slowly) so there are better ways to control the speed than a PID.
As for tread, we covered the polycarb wheel with self adhesive rubber foam. It does wear away with use, but does not damage the ball.
Sounds like we are using similar shooting speeds though I wonder why yours is going a bit faster. We do have a bit too much power, the motors are always cool to the touch. PID control is a quick and easy way to make sure the wheel is rotating at the correct speed (for different distance shots since our launch angle is constant). And the PID will give the ball a little extra juice when shooting (no slow down at all). Wheel speed is critical for accuracy, correct? How do you do it - assume the wheel speed for a given PWM setting? That will change as your batteries discharge!
But the thread is really about the wheel surface - did you try any other surfaces?
We tried several. Roughtop destroys the ball, duct tape over foam protects the foam but is a bit slick, sticky tape comes apart.
We are using a single wheel against a stationary backing. We are monitoring the speed using an encoder and controlling it using a simple feedback loop.
As mentioned, a high friction tread such as roughtop or wedgetop will simply shred the ball skin at high speeds. It is natural to think in terms of high traction material, but in reality the ball itself is already a high traction material, and more is not needed on the shooting wheel. We found a relatively smooth, hard surface gives the right amount of slip to avoid damage, while still accelerating the ball. We just left the hard, smooth rubber tread that came on the utility wheel we use.
You can get away with softer versions of rough top tread sold by mcmaster without damaging the balls for a shooter. Applications where the ball and tread need to slip, like an shooter loader, will shred the balls if you use rough top.
Banebot wheels are common, easy to interface, and have excellent grip. Why are you looking for a new type of wheel tread? What are you hoping to gain? I’m not sure you will get very far using different treads on the wheels.
I’ll second the call for BaneBot wheels… we’re using two on top and two on bottom, and it’s extremely reliable (based on our test shooting from the key)!
Agreed - our shooter works pretty well. We are fine tuning.
We think the ball should go further (given the wheel speed and if our equations are correct). We were thinking it might be slipping on the wheels (2 8" AMFIRST wheels mounted 2" apart) a little. If we can eliminate that slippage (if it exists), it might go further and/or be a little more repeatable.
We molded our own urethane around an aluminum hub. By doing this we were able to pick the material that was just “soft” enough to work well for us. Here’s a pic:
We placed the “125s” on the wheel by adding features to the 3D printed mold. We were also able to put a subtle curve into the wheel, to help match the radius of the ball and “center” the ball on the shooter as its spinning.
So far it has worked phenomenally. Balls are unharmed, and it appears to have just the right amount of grip.
Better = farther? What launch angle are you guys using? Maybe a reduced LA and bank shooting is smarter?
Ours shoots 20’ easily with a 60 degree LA - reliability testing starts tomorrow (now that encoder came in and works). But it should go further (according to the math) so I’m thinking it might be slipping on the wheel. The reduced distance may be lift and/or air resistance and/or friction with the hood - oh well, good problems to have I reckon.
We tried wedge top(from mcmaster) on the 8" First Wheel and it would occasionally damage the ball. But I think that had to do with our fasteners. We also tried the 6" higrip wheels from this year which tore up the skin consistently ( it was lik orange confetti). We ultimately stuck with the smooth 6" first wheel.
When we ran it without the 2 fisher prices we were launching stupidly high, so we backed up the other shooter hood, and made our Launch angle lower. Works better. I dont really think the lack of the 2FP mattered though…
Maybe you can tell us what we’re doing wrong this weekend.
I was not implying farther is better, just asking if that is what you meant. We should get a lot of practice this weekend. Our practice bot is not calibrated yet but the mechanics are firing on all cylinders.
