Motor Used for Shooting

[CalTran]

Just curious as to what motors people are using to siege the opposing towers with. With the unlimited-ness of non-CIM motors, what are people going for?

[MrJohnston]

We haven't finalized anything, but we've been prototyping with a CIM.

[Ginger Power]

775pro at 2:1 ftw

[PowerfulKitty]

Do you mean for shooting/throwing boulders or for climbing?

[CalTran]

Originally Posted by PowerfulKitty

Do you mean for shooting/throwing boulders or for climbing?

Title says shooting. I guess siege has 2 meanings this game...

[PowerfulKitty]

Apologies, it clearly says in the thread title.
775Pro motors are working very well for us

[kitare102]

We've so far been pretty successful using 775pros on a 4:1 versaplanetary gearbox with 4" wheels at ~4500RPM (max rpm for this setup). Once the stages come in we'll be upping that to 3:1, for a shooting speed of around 6000RPM.

If I had to give any advice, it would mostly be that versaplanetary gearboxes with low reductions are wonderful, not only for powering your wheel, but mounting it to your frame. A helpful note, using a CIM adapter on a versaplanetary and gearing it 1:1 (no reduction stages) is a wonderful way to easily and sturdily drive a flywheel with a CIM or Mini-CIM. This setup on a Mini-CIM nets around the same top RPM (~4500) as with our setup mentioned above. See Ri3D Greenhorns for an example of this use case.

I'd suggest using the 775pros (or 775s from Banebots), as opposed to BAG motors, CIMs, or Mini-CIMs, for the higher top RPM and power-to-weight ratio, seeing as a shooting mechanism is very unlikely to torque-stall and burn out the motor during regular operation. However, I'm sure there are ways to make any of those power a successful shooter.

[bEdhEd]

We've stuck with mini-cims our entire prototyping process and have been pleased with the results. I posted a video of said results in Robot Showcase. Our final design incorporates this motor. Actually, almost all our high power motors in the current design are mini-cims, including the drive system.

[Ether]

Originally Posted by kitare102

We've so far been pretty successful using 775pros on a 4:1 versaplanetary gearbox with 4" wheels at ~4500RPM (max rpm for this setup). Once the stages come in we'll be upping that to 3:1, for a shooting speed of around 6000RPM..

Reading between the lines, it sounds like you are not planning to control wheel speed, is that right?

[dkavanagh]

Been toying with the need for encoder to get consistent speed. Parts for prototype should be here tomorrow, so snowstorm-allowing, we'll get going with a prototype and hopefully find out.

[Boltman]

Can someone do a quick rundown of plus and minus of each (Mini Cim, Bag and 775 Pro) for shooters thanks.

[Mike Schreiber]

Originally Posted by Boltman

Can someone do a quick rundown of plus and minus of each (Mini Cim, Bag and 775 Pro) for shooters thanks.

For a shooter it really doesn't matter too much. The main thing that matters is your RPM and compression, I'm not convinced torque has a large impact on the shot as much as it has on spin up time / slow down after a ball is shot (which doesn't matter in this game). You want to get the wheels going at a specific repeatable speed to get an accurate shot - generally between 3000-8000 RPM with a 4" wheel(s) and depending on the distance / angle etc.

The advantage to a Mini CIM is that you can direct drive and be at around the right RPM, the disadvantage is that you can't really go any faster than free speed unless you gear up - which is silly. The Bag, 775, or 550 all have high free speeds and require some gearing down, but a versa planetary box makes that really easy. 550s are a little weird this year since you can't get them from VP or AM. Also consider packaging and where your motor / shooter will live inside the robot.

[Boltman]

Originally Posted by Mike Schreiber

For a shooter it really doesn't matter too much. The main thing that matters is your RPM and compression, I'm not convinced torque has a large impact on the shot as much as it has on spin up time / slow down after a ball is shot (which doesn't matter in this game). You want to get the wheels going at a specific repeatable speed to get an accurate shot - generally between 3000-8000 RPM with a 4" wheel(s) and depending on the distance / angle etc.

The advantage to a Mini CIM is that you can direct drive and be at around the right RPM, the disadvantage is that you can't really go any faster than free speed unless you gear up - which is silly. The Bag, 775, or 550 all have high free speeds and require some gearing down, but a versa planetary box makes that really easy. 550s are a little weird this year since you can't get them from VP or AM. Also consider packaging and where your motor / shooter will live inside the robot.

Cool Thanks!

[lark95]

Originally Posted by Mike Schreiber

550s are a little weird this year since you can't get them from VP or AM. Also consider packaging and where your motor / shooter will live inside the robot.

We have plenty left over from previous years so it is not a problem for us. However you can order the 550's directly from banebots.

We have done some more testing of the 550's on a 3:1 with 4 in wheels and are able to get a very straight shot at full speed.

[kitare102]

Originally Posted by Ether

Reading between the lines, it sounds like you are not planning to control wheel speed, is that right?

Both sides of our shooter have an in-line versaplanetary encoder which allow us to control the speed of each wheel. Funny story, we remembered when we were setting different RPMs for testing that 4500 is the max for our setup because we set the system to 6000 and the when we measured our speed with a tachometer, it never got above that 4500. Hopefully that speed will be achievable with the new gearbox stages.