CIM motor with AM planetary

[Ice Berg]

Hi,

I was wondering is anyone has used a CIM motor with the AM planetary gearbox. I'm not referring to the to their new gearbox designed specifically for the CIM, but the one generally used with the Fisher Price. Their site says it can be used with a CIM with slight modifications, but doesn't describe the changes. If anyone has used the CIM with this gearbox, info would be greatly appreciated.

-Seth

[AdamHeard]

To do it cleanly it requires a bit of work, but the end product is very nice.

We pulled the shafts from the CIMs and cut them to length on the lathe.

Reamed the pinions for a press fit on a lathe as well and then pressed them flush with the end of the now shortened CIM shaft.

Assembly is a bit odd, as you must bolt the plate to the gearbox first, then go through the AM planetary's facemounting holes to attach bolts to the CIM.

This will all make much more sense once you try it.

In the end, it works great, and has been very reliable so far.

[Ice Berg]

Thanks for the quick, detailed reply.

Is removing and then putting the CIM shaft back as tricky as it sounds? I plan to try this tomorrow. Do you have any tips on how not to ruin the motor, because this sounds like on of the few ways to mess up a CIM motor. Also how did you decide what length to cut the CIM shaft to?

[Schnabel]

Woah woah woah woah woah, isn't that considered modifying the motors? That's a direct violation of rule R53:

The integral mechanical and electrical system of the motor is not to be modified.

[Ice Berg]

Is there a way to use the gearbox without altering the shaft? Is altering the shaft forbidden by this rule? It does sound like it. If the shaft has to be cut down to use it with the gearbox then can it basically not be done?

[Tristan Lall]

Originally Posted by Schnabel

Woah woah woah woah woah, isn't that considered modifying the motors? That's a direct violation of rule R53:

Originally Posted by <R53>

...except as follows:
A. The mounting brackets and/or output shaft/interface of the motors may be modified to facilitate the physical connection of the motor to the ROBOT and actuated part.

Not quite a violation, if you don't take the motor apart.

If you do take it apart, but reassemble it, it's a more difficult call.

[AdamHeard]

You could shorten the shaft via a hacksaw and then grinding the edges nice, we just chose to do it on a lathe for a nicer cut.

The motors were disassembled and reassembled by an engineer who knows motors, and they were reassembled into the same configuration. This purely modified the shaft, and is within the rules as I believe. This has been allowed in the past with the warning of, "be careful taking it apart, you could mess it up".

[EricH]

Originally Posted by AdamHeard

This purely modified the shaft, and is within the rules as I believe. This has been allowed in the past with the warning of, "be careful taking it apart, you could mess it up".

Don't make me...

Previous years' rules and rulings do not apply to this year.

[AdamHeard]

Originally Posted by EricH

Don't make me...

Previous years' rules and rulings do not apply to this year.

I wasn't quote a previous year's rule, I was quoting intent that was stated about previous rules that are still written the same way.

It meets the rules. Period. I don't see anywhere it say you can't ever open motors as long as you don't modify them.

[EricH]

Originally Posted by AdamHeard

I wasn't quote a previous year's rule, I was quoting intent that was stated about previous rules that are still written the same way.

It meets the rules. Period. I don't see anywhere it say you can't ever open motors as long as you don't modify them.

I know you weren't. However, you were referring to a ruling made on a previous year's rules. Hence my comment on rulings as well as rules.

[Richard Wallace]

[puts on Robot Inspector hat] If the motor has the same free speed and free current in both CW and CCW directions after you put it back together, and they are the same as they were before you took it apart (within the limits given on the CIM data sheet), then you didn't modify it.

Did you measure the free speed and free current, CW and CCW, before and after? Are they still within CIM specs?

The best way to remove doubt is to show data.

[Daniel_LaFleur]

Originally Posted by Richard

[puts on Robot Inspector hat] If the motor has the same free speed and free current in both CW and CCW directions after you put it back together, and they are the same as they were before you took it apart (within the limits given on the CIM data sheet), then you didn't modify it.

Did you measure the free speed and free current, CW and CCW, before and after? Are they still within CIM specs?

The best way to remove doubt is to show data.

Whenever you take something apart and put it back together it will always be a little different.

The rule does not say functionally the same, it says modify.

Thus I suggest Q&A ... and I'll almost be willing to bet they'd say that a motor that was disassembled and then reassembled will be considered modified.

[Tristan Lall]

Originally Posted by Daniel_LaFleur

Whenever you take something apart and put it back together it will always be a little different.

The rule does not say functionally the same, it says modify.

Thus I suggest Q&A ... and I'll almost be willing to bet they'd say that a motor that was disassembled and then reassembled will be considered modified.

Your reasoning is sound, but I'd like to point out that FIRST feels that disassembling a custom assembly into COTS parts is (generally) sufficient to restore their COTS status (i.e. they are considered "unmodified"). Does that process work in reverse?

[Daniel_LaFleur]

Originally Posted by Tristan Lall

Does that process work in reverse?

This point is exactly why I said Q&A.

By strict definition it would be 'modified' even though it would still be functionally the same (and probably contain as much variation as an origonal from the factory).

I would still bet on the Q&A saying it would break <R53>.

[Travis Covington]

Any quality component or assembly, when disassembled and reassembled by a competent person, should function nearly the same as new. Any performance differences would be negligible, and would be apparent across all of the unmodified parts or assemblies of its kind. I don't see how taking something apart is "modifying" it in any sense of the word.

Edit: In all honesty though, I think removing the shaft is overkill. A dremel cutoff wheel works just fine and does no damage to the motor or the remaining shaft if you are cautious to avoid excessive temperatures when cutting.