Coolant on/off in Post Processor?

Hi all,
My machine has a water cooled spindle which is turned on and off in Mach 3 by the “Flood” output. I want to add an M8 command at the beginning of every job and M9 at the end, I can do this manually but would like it done in the post. This has to be a simple task but anyone have any idea exactly what to add to the Post Processor?

Many thanks,


Hi Bob,

If you just want one on at the beginning and off at the end, I would look in your post processor first for the section: “function OnInit()” and in there, probably near the end of this section, I would add a line:

post.Text (" M8 (Coolant on)\n")

and then look for the section: “function OnFinish()”. There I would add a line:

post.Text (" M9 (Coolant off)\n")

I believe that should give you what you want.

Hope this helps


Hi Paul,

Many thanks for your reply, I’ll give it try on Monday morning.