Shooter Help for 2nd Year Team

[Thorne]

Ta-Da! We have a functioning shooter!

Video: http://youtu.be/DASvBTc78GM

We're getting 20-30 feet from it with stacked wheels (as you suggested), two different CIM motors, a big one and a smaller one, the smaller one spins faster than the big motor, which apparently gave us the variance we needed. However, it was a little bit accidental, we put it all together and said "Let's see if it works!" and it worked fantastically! We also increased our compression and added some foam insulation tape for friction, which helped a lot.

Thanks again from the entire team, we look forward to the Silicon Valley Regional next week!

[Thorne]

Here's some photos of the final shooter, it was getting dark so the lighting's not great...





last one's a little blurry, but you get the idea :)

[Michael Hill]

Just curious...why two different sizes of wheels?

[Ether]

Originally Posted by Michael Hill

Just curious...why two different sizes of wheels?

Smaller wheel reduces tangential speed for entry. They don't have a speed controller.

[savagecreature]

Originally Posted by Michael Hill

Just curious...why two different sizes of wheels?

What Ether said.

We only have one cRIO and it is on the bagged robot. That is the first thing we will be remedying for next year. This was the best method we could come up with to vary the speed between the two sets of wheels. We have had a really steep learning curve and a really small team. It has been a very educational experience in so many ways.

[Ether]

Originally Posted by Thorne

Here's some photos of the final shooter, it was getting dark so the lighting's not great...

Is it just my imagination, or is the CIM not mounted perpendicular to the plywood?

[savagecreature]

Originally Posted by Ether

Is it just my imagination, or is the CIM not mounted perpendicular to the plywood?

They are supposed to be perpendicular, but one of the motors is indeed a little bit out of alignment. We will be replacing the plywood today since it got pretty chewed up while things were getting moved around yesterday. Today will be dedicated to cleaning up the design, adding the bucket frisbee hopper, and adding a pneumatic "pusher" that will feed the frisbees in to the wheels unless there is a way we can get it to just gravity feed.

Thank you (and everyone) for your patience and help. The team went from totally discouraged and not wanting to even go to regionals for fear that we would be the lamest team there again, to having a bit of hope that we can make a better showing than last year.

We did place 47th out of 50 last year, but that was primarily due to good alliances. We also received the Rookie Inspiration Award last year so the team wanted to show that we were taking that to heart and making progress.

[Bennett548]

Glad to hear your shooter is working well.

One thing I noticed was that you had to push the disc into the wheels. Make sure the disc isn't dragging between the walls after the first set of wheels (i.e. the walls should be >11" apart). This would require moving the left wall to the left a little bit; it looks like the distance between the right wall and the wheels is good.

As far as local teams, usfirst.org has a search tool for finding teams in your area. Here are all the teams within 25 miles of Alameda: http://tinyurl.com/c9f5cw2

[savagecreature]

Originally Posted by launchloop17

Glad to hear your shooter is working well.

One thing I noticed was that you had to push the disc into the wheels. Make sure the disc isn't dragging between the walls after the first set of wheels (i.e. the walls should be >11" apart). This would require moving the left wall to the left a little bit; it looks like the distance between the right wall and the wheels is good.

As far as local teams, usfirst.org has a search tool for finding teams in your area. Here are all the teams within 25 miles of Alameda: http://tinyurl.com/c9f5cw2

Thank you! We have a pneumatic push rod to shove the discs, but I will be sure to share your comments with the team. The push rod has not been fully tested yet so your suggestion may be a good solution if we run in to trouble with it tomorrow at pit day. I will also make sure some of the team members reach out to the list of teams that you provided after we are done with the SVC Regional.

[cmrnpizzo14]

Good luck at SVR, if there is a webcast I will watch you guys!

Try not to get too discouraged, being a 2nd year team is often world's better than a rookie but there is still a lot to learn. Know what your strengths are and what you can do to help the alliance. While you are at SVR, there will be a ton of great teams there. Try and make time to go talk to 254, 233, 118, 148, 846, or 973 (sorry if I forgot anyone, put yourself down if you want to be on the list!) they will definitely be able to help you guys develop as a program.

Good luck!

[philso]

You may want to have a look at the following thread started by my good friend Allen Gregory of Team 3847, especially post #16 where he describes how to make a 1:1 VersaPlanetary gearbox.

www.chiefdelphi.com/forums/showthread.php?t=111360&highlight=small+wheel+shoo ter


The gearbox will take the side loads off the motor shaft preventing premature wear/failure. We originally had a single wheel mounted directly on the shaft of a Mini-CIM. After about 20-30 shots (some with extreme compression), the rear bearing of the motor was worn into an oval and the motor armature dragged on the inside of the magnets. Since we did not want to wait for another motor, we ended up changing to RS550's with a CIM-ULATOR gearbox that I had left over from the previous year. The CIM-ULATOR also took the side loads off the motors.

[Chris is me]

Side loads were not a problem for us this year direct driving off of CIMs and mini-CIMs with a very similar shooter. As long as your compression isn't insane (10.5 inches from tip of wheel to side wall is what we used) there shouldn't be any problems.

One tip I would give you guys to get a more accurate shot that curves less. It looks like your shots hook right, away from your wheels. We found this curve was a result of the frisbee being compressed but not constrained properly. The edge of the frisbee closest to the wheels was allowed to rise up, and thus discs left the shooter in a crooked manner. If you have some kind of physical guard (e.g. a piece of low friction plastic) mounted right above the shooter wheels to prevent this "popping", you may get a more consistent shot.

[team4384]

The channel opposite to the wheels doesn't seem to have any friction, the frisbee will slip, loose energy and not fly far enough. Consider taping friction tape or at least soft sided velcro to the inside of the channel opposite to the wheels. This grip the frisbee and the fast spinning wheels will generate spin and push the frisbee out.

You can get 3M friction tape (cloth electrical tape) at home depot for about $4 or so.

[Ether]

Originally Posted by team4384

The channel opposite to the wheels doesn't seem to have any friction, the frisbee will slip, loose energy and not fly far enough. Consider taping friction tape or at least soft sided velcro to the inside of the channel opposite to the wheels.

They already did that. Ya gotta read the whole thread:

Originally Posted by Thorne

We also increased our compression and added some foam insulation tape for friction, which helped a lot.

[savagecreature]

Originally Posted by cmrnpizzo14

Good luck at SVR, if there is a webcast I will watch you guys!

Try not to get too discouraged, being a 2nd year team is often world's better than a rookie but there is still a lot to learn. Know what your strengths are and what you can do to help the alliance. While you are at SVR, there will be a ton of great teams there. Try and make time to go talk to 254, 233, 118, 148, 846, or 973 (sorry if I forgot anyone, put yourself down if you want to be on the list!) they will definitely be able to help you guys develop as a program.

Good luck!

Thanks so much! I will pass this along to the team.