shooter wheel tread types

[wireties]

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?

Opinions, suggestions?

TIA

[martin417]

Originally Posted by wireties

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?

Opinions, suggestions?

TIA

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.

[wireties]

Originally Posted by martin417

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.

Top and bottom wheels? Or just bottom wheels?

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?

TIA

[martin417]

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.

[wireties]

Originally Posted by martin417

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.

Thanks for the info!

[jspatz1]

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.

[Jeffy]

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.

[Jon Stratis]

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)!

[wireties]

Originally Posted by Jeffy

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.

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" AM FIRST 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.

TIA

[Brandon Holley]

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.

-Brando

[wireties]

Originally Posted by Jon Stratis

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)!

Thanks - the banebots wheels look nice but we are stuck with 8" wheels at this point.

[wireties]

Originally Posted by Brandon Holley

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.

Beyond awesome! ... but hard for us to duplicate in 10 days or so.

[sdcantrell56]

Go with colson wheels. Hard to beat them

[JohnSchneider]

Originally Posted by wireties

Beyond awesome! ... but hard for us to duplicate in 10 days or so.

Make sure to let us know if you find something that works better

We adjusted the hood of the shooter and got better results...we are taller though...but have been having great success with the KOP wheels from 2009.

[wireties]

Originally Posted by animenerdjohn

Make sure to let us know if you find something that works better

We adjusted the hood of the shooter and got better results...we are taller though...but have been having great success with the KOP wheels from 2009.

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.