We’ve been prototyping a handless “hand” system for our bot. Can we use a CIM motor to power a shop vac vacuum plenum system and still stay within the rules? I know several teams last year used a shop vac to get soccer balls to the goal using vacuum. We’re taken with the simplicity of using a handless system in the same way since the tubes do not weigh very much. Any pearls o’ wisdom would be appreciated.
Thanks!
Steve Miller
Team 3355
Arlington, Texas
A shop vac system is perfectly fine as long as you replace the motor with a KOP motor. A cim might be a bit over powered though, I don’t know if it would run at the right speed. Might be an application for the FP motor.
We tried doing this last year to hold the ball. It didn’t work with a 1:4 overdrive out of the cim. If you do try it needs to have an even higher gearing. If I understand it correctly, you only need enough torque out of the motor to turn the impeller. Therefore it would probably be better to use one of the banebots since they have much higher rpms.
That is only half your problem. Quick release of the game pieces is also required.
I think we had one of the more successful vaccuums last year. We had 2 FP’s turning 2 stacked shop vac impellers (the output of one feeding the input of the other). I know how that system compared to our regular shop vac at 120 volts so I tried our shop vac with the same cup we used last year on this years donuts because, like you, I thought it would be the simple solution and hey 2 years in a row would be cool. BUUUTTTT the suck was enough to hold the donut in the vertical but any little bump on the off side resulted in seperation.
If you get it to hold better thanb that I’d love to see how ya did it!!!.
Good luck
Bruce
If you want to try a vacuum, I would highly recommend you use the FP instead of the CIM. With the CIM motor, you need to overgear it in order to get the motor to spin fast enough for good airflow. The FP spins that fast “out of the box” and is lighter.
Not to mention - you REALLY want all 4 of your CIMs in your drive this year.
When air is flowing (ie when the motor is energized and a held tube is not blocking the airflow), the impeller will impose a substantial load on the motor because it is accelerating a lot of air through the system.
Take a shop vac. Turn it on. Listen to the sound of the motor. Now cover the intake with your hand. Hear the pitch of the motor increase noticeably? The motor speeds up when you cover the intake and block the airflow. That’s because there’s less load on the motor with the airflow blocked.
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We also used the FP motor last year with great success, We thought it would be a quick clean solution this year, however Initial testing shows we can pick up a tube , but drop it with a sudden move or bump. We will probably go a different route.
Team 1771 used an impeller with a CIM motor in 2010 and (I think 2008). I’m not sure of the gear ratios or anything. All I know is that it worked REALLY GOOD. (I remember stories of one of our mentors taking the funnel we used in 2008, put it against a glass window, turned it on, and the window started to warp inwards… :yikes: )
As for a quick release-
What we did in 2010 (before we switched to a roller after Peachtree) was we used a “pop-top”. Basically a tube that was in the same system as the vacuum, powered by a pneumatic cylinder. When we kicked, it was programmed to pop up, releasing the vacuum pressure for X milliseconds before kicking.
I said this on another thread, but due to the limited surface area available for a vacuum pickup, you probably need higher vacuum than you can get with a shop vac. Look for air ejectors. These devices use the Bernouli principal of air through a venturi to create very high vacuum levels (much higher than a shop vac, but with very little flow) The limitation with these devices will be flow. If you don’t get a good seal (read, nearly perfect) you can’t develop much vacuum.