MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.

Download Now

Report as inappropriate

A rumba board has 6 steppers may be you can ad this https://www.reprap.me/stepper-expander-x3.html you have 9!

https://forum.e3d-online.com/threads/adding-a-fourth-extruder-to-the-rumba.1892/ more info

https://reprapworld.com/products/electronics/ultratronics/ultratronics_pro_v1_0/ an other board with standard 4 extruders.

info about smoothie board and multiple extruders http://smoothieware.org/multiple-extruders

So and now go figure it out and report back when it works ;-)