Alternative to CIM with 12:1 GearBox

[Daru]

Hi guys,

We're going to need 6 drive motors this year. We determined the CIM with Banebots gearbox would be ideal, but we need two more similar to that. Can you recommend anything that would be about the equivelant? They don't need to be exactly the same, however the closer they are the better.

... actually, maybe I need to rethink it to work with only 4 CIMs.


Thanks,
Dave
706

[Cowmankoza]

You could always get the Andy Mark planetary that converts the fischer price to the same rotations as the cim. (But in the end you would probably benefit more from rethinking it to work with 4 cims as opposed to the addition of 2 extra motors)

[AdamHeard]

With some gearing you can use the one large cim and one small.

Or you can use the FP planetary from andymark

[Tytus Gerrish]

if your looking for the effedt of 4 Cim mortors without thinking about it too much the planetary grom andymark is the way to go. it has the same hole pattern and dimentions as a Cim. and similar speed output.

[Daru]

Actually we're doing this:
Chassis Drawing

I don't think using 4 CIMs would be easy (keeping power into consideration)
It would allow us only 2 CIMs per 'direction'

We'll probably go with the AndyMark gearboxes.

Thank you!
Dave

[Joe Johnson]

If you are intent on a 3 motor per side drive, you may consider the type of arrangement shown in this picture. All it would require is a .8 module gear that is approximately 1/4 the number of teeth of the 50T gear that is on the CIM (12 or so teeth should do nicely). Press it on the FP motor and then figure a mounting method to allow the motor to mate with the 50T.

If FIRST would have given Banebots more time, I think they would have built the mounting system right into the mold for the plastic housing. In fact, given just a little more time, I may have gotten my request to have the pitch of the gears for the adapter changed to 32 DP to match the gear that the FP comes with (32 DP = .79375 module which is very close to but not exactly .8 module).

If we had done this (and changed the housing tool to accept FP motors and had we know how many teeth were on the FP motor), we could have made gearbox that could take up to 4 motors (2 CIMs and 2 FPs) without requiring any motor changes. Now THAT would have been cool.

Ah well... ...perhaps some other year.

Joe J.

http://www.chiefdelphi.com/forums/at...1&d=1168351452

[Ianworld]

I may have read your post wrong but it actually sounds like you're trying to drive each wheel independently with its own motor. One thing you could look into is connecting your wheels with roller chain. That way you dont' need to power each wheel indpendently.

[Daru]

We intend to use 6 omniwheels, 4 of them oriented in the forward-backward direction, and two of them in the left-right direction to allow side to side translational movement.

To use only 4 motors, we would need to link the forward-backward wheels with chain, like you suggested. I fear that using one motor on each side of the robot would severly limit what pushing power we would have.

Two two CIM-like motors would be for the side-to-side translational movement (and maybe turning), which we don't intend to use to push with, so lacking power there would be acceptable. We would like it to be close to the same speed, however it's not too important as long as it moves us fairly quickly.

[NK2007]

Is this what you are trying to do?

This is the bike cim with the banebots gearbox, something I cadded up for an arm design we had.
http://www.chiefdelphi.com/media/photos/26252

~neill

[Daru]

That would be overkill for the drive, but something like that for our lift might be perfect ;D

[Brandon Holley]

Thats a pretty complex drive system, but i must say its creative.

You may want to think about your pushing ability in general with 6 omni wheels there. No matter what direction you get pushed from, an omni wheel is able to slide freely.

[Billfred]

Originally Posted by Brandon Holley

Thats a pretty complex drive system, but i must say its creative.

You may want to think about your pushing ability in general with 6 omni wheels there. No matter what direction you get pushed from, an omni wheel is able to slide freely.

And yet it's been competitive in the past; 343 did a similar design in 2002, and won the KSC regional that year. There's some videos on Google Video of their matches, and one picture on CD-Media: http://www.chiefdelphi.com/media/photos/13692

(Of course, they had metal-roller omniwheels--you can't do that anymore.)

[Ben Piecuch]

This 6-wheeled omni drive setup is exactly what Team 343 did in 2002. Here is a picture of their robot. I can see that they used the Fisher-Price motors and gearboxes to drive their "sideways" omnis. I don't know what motors they used for their "forward" omnis. This robot won at least one Regional Competition, and was extremely effective at moving TWO 180lb goals around the field. So, I think that would probably put to rest the question of "how much traction" can you get from this setup.

This robot has a very special place in the students and mentors of team 343. I'm sure any of them could tell you more about it.

BEN