Double 775Pro DoubleBack CIM-SIM-CIM-ile

Last crawled date: 1 year, 10 months ago

So, you like that 3CIM Ball Shifter from VexPro but you also like those 775Pro Motors that have all the power of those FRC Favorite CIM Motors but offer a net weigh savings of something like 2lbs per motor? Torn between two loves.

Also, don't those Coke Can Sized CIMs make things a little tight in the middle of your FRC Robot some years?

Be honest, there have been years when you've looked longingly at other robots with svelt & sexy ball intakes running right down the middle of their machines. You'd really want some of that center intake game piece action... ...if only those big old CIMs weren't holding you back... ...I see you nodding your head. You don't have to say more...

What's a FIRST FRC Maniac to do?

If you have access to a 3D printer and some coins you can have your cake and eat it too.

What to buy (for every 2 775Pro Motors you want to have drive the Vex 3CIM Ball Shifter):
- (4) AM-0931 Ball Bearing, 8MMx19MMx6MM Flanged
- (2) AM-0930 Output Shaft for CIM-Sim Gearbox (if you have a lathe and some 3/8" hex shaft you can easily make one/both of these from scratch)
- (1) 217-3107 11t CIM Gear w/ 12t Center Distance
- (2) WCP-002 32DP 12T 775Pro pinion
- (1) WCP-006 32DP 40T gear
- (1) WCP-008 32DP 60T gear
- (2) 775Pro motors
- (4) M4X30mm screws (McMaster 91292A130)


3D print Housing 1 and Housing 2. And you're in business.

Key Features:

*** Mounts like a CIM in the same place as a CIM with the same holes as a CIM... But has the motors "Doubled Back" over the gearbox so that you have more room in the center of your robot for balls, totes, etc.

*** 3.3:1 added ratio from 775Pro to CIM-like shaft. Ideal "free speed matching" ratio for a CIM would be 3.5:1. If you were using a 12T pinion with the CIM, then if you use a 11T pinion on the CIM-like shaft, you get 3.6:1. Close enough.

*** Replace motors without removing gearbox or even taking gearbox apart.

*** Air paths for cooling 775Pro -- you really need air flow if you want to keep the smoke in these 775Pros. Let 'em breath.

*** Multiple Positions to mount on 3CIM Ball Shifter (note, Side CIM has mounting holes that are not square to the CenterLine of the gearbox) gives some packaging freedom.

*** Ball bearings because, really, who DOESN'T like ball bearings if they can get them?

*** View gear mesh *without* taking gearbox apart -- holes so you can peek in and see what those wascally involutes are up to...

*** Solidworks files included in ZIP file (Pack & Go -- includes 3CIM Ball Shifter and custom configurations for other mountings if you don't like Universal mount).

UPDATE 2016-12-19: Currently there is one bit of the housing that is a little closer than I'd like it to be. Look for an update fixing that soon. JJ

UPDATE 2017-01-05: About to test the idea that 3 775Pros can do the job of 2 CIMs. We'll know soon enough...