Turn on fans prior to "RatOS: Heating bed..." | Rat Rig Community [Unofficial] | Page 1

blazing hawk Feb 7, 2026, 4:59 PM

#

I need some help finding out where I would put some code to turn on some fans prior to "RatOS: Heating bed..." step when I start a print.

I thought it would go in the start_print macro, but it appears Rat OS is doing something prior to that macro running?
At this point, I have tried quite a few things but am brain dead.

Thanks for any guidance.
Edit: I should add, I am on Rat OS 2.1 RC4

mortal crescentBOT Feb 7, 2026, 4:59 PM

#

To help others find answers, you can mark your question as solved via Right click solution message -> Apps -> ✅ Mark Solution

stoic lichen Feb 7, 2026, 5:27 PM

#

Look up in the docs for macro hooks maybe

blazing hawk Feb 7, 2026, 5:39 PM

#

I have tried that with several different ones they have:
_USER_START_PRINT_BEFORE_HOMING
_USER_START_PRINT_HEAT_CHAMBER
_USER_START_PRINT_AFTER_HEATING_BED

Sometimes Klipper says it doesnt recognize the user maco, sometimes it acts like it recognizes but doesnt do anything with it.

#Turn on fans prior to "RatOS: Heating bed..."