Need motor suggestions

Technical Motors
1

Our team needs to re-evaluate a different motor & configuration that we are using for our trackball manipulator rotation arm and could use some helpful suggestions.

Currently we have a ~ 9:1 gear reduction gear ratio set up with a globe motor but it isn’t cutting the mustard and if we can’t find a suitable alternate we might consider gearing down even more…

We like the globe motor for its size and weight while the Cim motor is very heavy and might not be a good fit for us.

We have read on this forum where other teams are having problems with the plastic worm gears on some of the Keyang KOP motors stripping the plastic worm gears, so it sounds like these are not a good option for this…

Also, the rules mention FIRST Tech Challenge (FTC) motors (Innovation First part number 276-2163), but I am not able to locate these to evaluate them…

Is there any other suitable motor that we might use for this application?

What might you suggest?

Thanks

Additional motors specifically permitted on 2008 FRC ROBOTS include:
All motors, actuators, and servos provided in the 2008 Kit Of Parts,
HITEC HS-322HD servos, FIRST Tech Challenge (FTC) servos (Innovation First part number 276-2162), FIRST Tech Challenge (FTC) motors (Innovation First part number 276-2163), One or two additional 2-1/2” CIM motors (part #FR801-001 and/or M4-R0062-12 in addition to those provided in the Kit Of Parts. This means that up to four, and no more, 2-1/2” CIM motors can be used on the ROBOT.

<R60> Items specifically PROHIBITED from use on the ROBOT include:
Electric motors and/or servos different from, or in addition to, those in the Kit Of Parts, with the exception of those specifically permitted by Rule <R59>.
Electric solenoid actuators (note: electric solenoid actuators are NOT the same as pneumatic solenoid valves – the latter are permitted, the former are not).

2

Your best bet is probably the Banebots RS-540 or RS-550 through one of the banebots planetaries. They’re light and have a higher peak power than the globe. You’ll need to be careful to run them at something like 25% of the stall torque, however, or you’ll quickly melt them. Your other option is a FP through the FP tranny or a BB RS-540 tranny, with the same caveats.

3

I would def. stay clear of the FTC motors… they are basically just hobby shop small R/C truck servos. Nothing what you need to power your arm.

4

The first step might be to calculate the load of the arm, and then divide by the reduction to find out what torque the motor needs to have. Also you should keep in mind that the “stall torque” is the maximum torque the motor can produce, it is NOT the torque that the motor is designed to operate at. Normal torque load should be about 10 to 25% of stall torque. If you have a long arm with a ball gripping device on it as well as the weight of the ball, you may find that if you want the arm to move anywhere near fast, you’ll need to use the CIM motor on it.

Also look at using a gas spring (available from McMaster-Carr among other sources) to help hold up the arm. This may or may not help…but last year it let us use a small motor driving a long arm to play Rack-N-Roll.