pic: WildStang 2017 - Shooter Module

this looks really nice. any chance you will post the cad files?

It looks like they posted their CAD files for this year in this thread.

This thing is beautiful! I think this is the first FRC robot subassembly I’ve seen that could honestly be moved directly to being a combat robot subassembly. Swap the pulleys with V belts and the wheel with a single tooth drum and you’ve got an excellent weapon system for a hobbyweight (12lb) bot.

Edit: How much does this weigh, out of curiosity :wink:

775pros have less power than beetleweight weapon motors (and are heavier)

Thanks! The real version came out almost as awesome as the render. https://imgur.com/a/T4AEC

Also, huge props to Pwnage and their sponsor Genesis Automation for making the side plates for us.

Weight is around 2 lbs.

Spaced on the 775pro. Shouldn’t be much of an issue, as the 775pro has the same mounting hole pattern as most 45mm brushless motors.

Hey! Just wondering, what was the material you used for your flywheel? My team experimented with a couple this year, but we want to know what others used to maximize performance. Thanks!

Really cool. Compact, powerful, pretty.

But since I’ve seen 1986 had four 775pros (1388 watts) on their shooter for est 5+ balls/second, I’m wondering how many balls/second one 775pro (347 watts) is able to do?

We used a mini-cim (215 watts) and were only good for one/second.

Also, using a belt on an 18K rpm motor–does this cause any problems? I don’t think there are any belts designed for that speed.

Not 111, but our 775pro shooter was able to get 6/second reliably, but if accuracy didn’t matter, we could’ve pushed it harder. That being said, there was a definite decrease in power in the shot by the end of each “round” of balls (5 balls).

From our prototyping, a single 775pro was sufficient for our shooter, which obviously helped with our packaging needs as well. :slight_smile: It helped that our wheel was very light. It would be different if we had used a larger diameter/heavier wheel (and also PID would have been tuned differently).

These were each driven by a Talon and used the CTRE mag encoder for feedback. We focused less on shooting at the regionals, but for champs we tuned the PID for these very carefully, running a fairly aggressive setup to get it back to speed ASAP.

Combined with our feed system, we measured (via slow-mo video) that we could get 8-10 balls per second from each shooter. For accuracy we slowed this a little and in reality shot about 6 per second per shooter. With the PID tuned well and a nice constant stream of balls through the feed system, this setup worked really well. (We had prototyped a belted floor but did not add it for space and weight reasons, but that was even more efficient at getting balls through.)

Specifically it was Fairlane wheel DR-9502-35UR-R, available here.

Alone these don’t have enough inertia to be an effective shooter wheel, so we added mass with our aluminum hub and the additional steel flywheel discs on either side.

What your final motor can do is highly dependent on the input speed. Most all the accurate shooters this year had pre-feed stages that substantially accelerated the balls.

Could you post the video so we can see this? Curious

Did you have any trouble with the press on pulley for the 775 Pro? My team is thinking about using one of these in our offseason design.

No problems at all. Takes under 30 seconds with a vice to get them on.

Seconding the request for video! Would love to see it in action.


I have a question about the Fairlane wheel:

Do you guys mount it such that the teardrop shapes are bulging in the direction of the rotation or against it? In other words, if viewed from the side, the shooter wheel is spinning clockwise, do the teardrops on the “top” of the wheel bulge to the right or to the left? Or is there no difference for all practical purposes?

I ask because we saw all of these really good shooters using Fairlane wheels and bought one to mess around with in the offseason.
It has been a point of debate on the team as to which direction the teardrops should bulge. :slight_smile:

I’d say the performance difference would be neglegable, but the difference in wear would be interesting, as the direction would either have the point of the teardrop areas (thicker rubber) or the bulge of the teardrop areas (thinner rubber) make “first contact” with the ball. Correct me if I’m wrong, but orienting the wheel (in this case) with the bulges pointing outward from the motor would potentially result in more wear.

My guess would be that having the thinner rubber make first contact would result in more wear.

In any case, we have the thicker rubber or “point” of the teardrop contact first because it “looks right.” XD