Extra CIM.... question

From reading the rules… i know that we are allowed an extra CIM(A total of 5 CIMs on a bot)

now the thing I’m having trouble finding in the rules is are we allowed and extra ToughBox trans… so a total of 5 ToughBox trans on a bot

any info on this would be great


I don’t believe that there are any restrictions on transmissions.

No limit on the number of toughboxes other than you cant have more than 120lb’s worth.

If the 5th wheel isnt for the drive train dont be so dead set on using a toughbox. Just a thought you could definitely find other means of successful transmissions.

You don’t need the toughboxes for the drive motors either, you could make your own or use AM Shifter or AM super Shifters or a BB planetary or DeWalt something like that. That said, if you are a rookie team without many skilled machinists, the kit transmission would be the easiest way to go.

If you are set on using the Toughbox for the 5th CIM but are using it for non-drive, a Toughbox Nano would provide the same thing for smaller size and weight.

Toughboxes weigh alot. Weight = BAD. FRC robots are almost always right on the 120lb edge of things, and every ounce counts.

For high-speed rollers, direct-driving off a CIM or gearing it down with chain alone would probably work fine.

Very true!

That all depends on how the robot is designed. Granted, most teams are at or over the weight limit at their first regional… but our team has consistently been under the past 3 years.

So much, in fact, that we’ve added 10-20 lb steel plates on all of our robots just to get up to the weight limit. Last year, we were smart about it, and integrated the steel plates into our design from the beginning :slight_smile:

But Toughboxes can easily be lightened if you have access to a lathe. You can replace the extruded box with standoffs, and the internal gears can easily be swiss cheesed. Our favorite method of lightening the gears is to turn a .125 deep pocket into both sides on the lathe then drill six holes on the rotary table.

Of as we often do, take the gears and bearings from the Toughbox, maybe swap in different gear ratios to achieve the desired robot speed we’re looking for, then design our own housing, whether CNC milled or CNC punched sheet metal.


For high speed applications, our favorite method is to just use timing belt directly from the CIM motor drive shaft. This works good for 1:1 to 4:1 reductions. It’s much quieter than roller chain at high speeds (what? it’s faster than Aunt Jane at planting seeds?), and at these speeds the timing belt is pretty tolerant of loose belts.


Please remember that there is a cost constraint that might come into play on your robot.