BitRunner - Does it control spindle speeds?

I’m pretty sure it won’t control the speed of my Makita RT0700CX4, but the installation guide is a little contradictory (unless it does control the speed!):

3. Load the G-code (.nc file) in Carbide Motion. The G-code instructs BitRunner to automatically supply power to the spindle when appropriate. The G-code also triggers alert boxes to open in Carbide Motion which provide you with information about changes you need to make to the router RPM and end mills.

NOTE: If you’re using Carbide Create to design your project, all of the G-code commands for tool change and spindle control are baked in; so, there’s no need to change anything.

Thank you

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Hi Peter,

No it does not (and cannot) control the speed of a trim router automatically, since trim routers do not have any external interface that it could connect to to do so.

What happens is:

  • Carbide Create generates code that does include “spindle” start (M3) commands as well as RPM values (e.g. S18000). Hence the footnote.
  • When Carbide Motion sends e.g. M3S18000 to the controller, GRBL has a default behavior of activating the “PWM” output signal, at a duty cycle value that depends on the RPM value sent after that S command.
    • On a Shapeoko equipped with a trim router and no BitRunner, this PWM generation is useless/unused.
    • On a Shapeoko equipped with a VFD and spindle, the PWM signal is picked up by the VFD, and the RPM is then automatically adjusted to the set value.
    • On a Shapeoko equipped with a trim router and BitRunner, the BitRunner will detect when the PWM is active (but will not do anything with its duty cycle), and will activate its internal relay to switch on power to the trim router (which will then run at the RPM set on its dial manually)

Sorry if “no” was enough of an answer, but I felt like describing why :slight_smile:


Thank you @Julien, I knew I could rely on you - and I prefer to understand why than not :+1:

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