Motor driven catapult gear ratio

[themick07]

For those with motor driven catapults, what are your setups?

[Madison]

Originally Posted by themick07

For those with motor driven catapults, what are your setups?

2 BAG motors at 466:1.

Edit: That's pulling the catapult down -- we are not using the motors to throw the ball. It's unclear what you're after here.

[geomapguy]

Originally Posted by Madison

2 BAG motors at 466:1.

Edit: That's pulling the catapult down -- we are not using the motors to throw the ball. It's unclear what you're after here.

I think he's referring to Boom Done type shooters...like Spectrum's and our robot.


To OP, 15.33:1 for our shooter

[themick07]

Yes we are looking to change our catapult firing mechanism from springs to motor driven.

[TheKeeg]

Originally Posted by themick07

Yes we are looking to change our catapult firing mechanism from springs to motor driven.

Why?

[themick07]

Originally Posted by TheKeeg

Why?

Our springs were inconsistent and wore down after like 50 shots. Also we couldn't move the catapult arm without releasing it completely. Motors would be more consistent and reliable.

[Ether]

Originally Posted by themick07

Our springs were inconsistent and wore down after like 50 shots... Motors would be more consistent and reliable.

What factors do you think might make the motor performance change during the course of a match.

Also we couldn't move the catapult arm without releasing it completely.

What does the above sentence mean?

[who716]

Originally Posted by themick07

Our springs were inconsistent and wore down after like 50 shots. Also we couldn't move the catapult arm without releasing it completely. Motors would be more consistent and reliable.

we have been having trouble with consistency with our motor shooter specifically when the battery gets low

[TheKeeg]

Originally Posted by themick07

Our springs were inconsistent and wore down after like 50 shots. Also we couldn't move the catapult arm without releasing it completely. Motors would be more consistent and reliable.

I am just curious how you plan on achieving this considering the robot is bagged all but 6 hours. I am sure there is a plan in place, but it seems like a pretty large design change for competition season. Have you already designed/built the new catapult and just need to place it on the robot it or is it an addition to the original shooter?

[SRaymond]

2 CIMs to a toughbox mini to a chain drive (not sure of the sprocket's tooth numbers)

Works like a champ!

[IndySam]

4 775's on 5:1 Versas with a secondary reduction on 2:1 for a grand total of 10:1.

Its a linear shooter not a traditional catapult

[marccenter]

For us, we are using dual mini-toughboxes with 1-CIM and mini-CIM, one on each side, then double chain reduction of 15 from the CIM output to a 26 tooth sprocket, then a 36 tooth sprocket to a 96 tooth sprocket. Total reduction should be nearly 27:1. We are using 1/2 EMT loop connected to two arms. The 96 tooth sprockets were made by our sponsor (Andy Mark six hole pattern - 1.875 inch bolt circle).

We're throwing the ball from white line past the other white line, over the truss, during the Southfield MI event. We missed some shots because we didn't have the shooter dialed in perfectly (made 2, missed maybe 5, 10 pointers) and hit the upper target area bouncing over the top.

We also calibrated for shooting into the 1 point goal over robots. We were 1 for 2 with little practice.

Thanks CD for previous posts that led us in the direction to have more velocity and less torque (F = 1/2 * mass * velocity squared)

Our design is based on the Boom Done design completed in the Robot for 3 Days competition. This year's motto: If Joe's team can do it in 3 days, we can do it in 6 weeks!" (4-6 high school students, 1-1/4 engineers, 1 dad for 6-8 hours).

Best regards,

[EricWilliams]

He means that the catapult arm can only be stopped halfway through its motion path with a great deal of effort in a fairly unsafe manner. We had the same problem in 2008 with a spring driven catapult. Also, dry firing was extremely risky, for us.

[matthewdenny]

We use a motor driven catapult with a toughbox+2CIMs+35 chain and sprockets.

Total reduction with gearbox and chains is about 25:1.

We also use a pneumatic cylinder on the back with ~8" lever arm that applies 40 lbs of pressure or so.

It can score with just the motors but the range is limited to a small window around 8' out, withe the pneumatics it is significantly stronger.

[themick07]

Originally Posted by matthewdenny

We use a motor driven catapult with a toughbox+2CIMs+35 chain and sprockets.

Total reduction with gearbox and chains is about 25:1.

We also use a pneumatic cylinder on the back with ~8" lever arm that applies 40 lbs of pressure or so.

It can score with just the motors but the range is limited to a small window around 8' out, withe the pneumatics it is significantly stronger.

What is your catapult arm made of?