First Robotics Books

[Ether]

Originally Posted by Chris is me

Not from 75, but I think they meant that a big/small CIM combo geared for the same free speed as a 2x small CIM combo would draw more current under load.

Thanks Chris. I'm trying to parse what you wrote. Are you saying that the comparison was between

a) 2 small CIMs driving a gearbox

and

b) one small CIM plus one large CIM driving one gearbox (so that the small and large CIM are being driven at the same speed ?

I wouldn't have guessed that from what was written.

If what you say is true, sure that's not optimum. The large CIM's NLS is half that of the small CIM. There's no way to operate such a design efficiently.

[Chris is me]

I believe a larger pinion was put on the large CIM to compensate for this.

[Ether]

Originally Posted by Chris is me

I believe a larger pinion was put on the large CIM to compensate for this.

If the large and small CIMs were geared so that each one was running at the same percent of its own no-load speed, then the large+small combination should be more power-efficient than the small+small combination, according to the motor curves I have for the large and small CIMs.

If there's a piece of the puzzle that's missing perhaps someone from Team 75 who was involved in this analysis would clarify.

[IndySam]

AndyMark produced a special version of their super-shifters to allow the use of one big cim and one small.

[Ether]

Originally Posted by IndySam

AndyMark produced a special version of their super-shifters to allow the use of one big cim and one small.

You don't happen to have the model number for that somewhere in your notes do you? I couldn't find it on AndyMark. Thought maybe if I Googled it I could find some hits.

[IndySam]

Originally Posted by Ether

You don't happen to have the model number for that somewhere in your notes do you? I couldn't find it on AndyMark. Thought maybe if I Googled it I could find some hits.

AM Gen 2 came with different side plates for the large cim.

http://www.andymark.com/ProductDetai...ctCode=am-0076

check out the pdf for a good view.

http://d1pytrrjwm20z9.cloudfront.net/amshifter2-asm.pdf