A new OpenRC tractor tool is out, the fertilizer!!
You'll need a micro motor
Link
I recommend more than 100rpm for this use. Moreover, you'll need some M3 screws and nuts. I connected it with the tractor ESC so it runs accordingly. In fact, in old tractors as this one, it used to work like this.
Hope you like it! ;)
With OpenRC tractor, possibilities are endless, new tools keep coming...so stay tuned!! (see below updates and get more details at (http://www.makitpro.com)
Video in action
https://www.youtube.com/watch?v=HJo-eUfV0fI
https://www.youtube.com/watch?v=Dlf3Jw0A2M4
Download original Tractor from: http://www.thingiverse.com/thing:1967086
Makitpro
