Seems some people get that problem and others, like me, never do but now I have said that
Anyway maybe adding this to your macropump would help, it should stop the machine if the spindle is 10% out from commanded speed.
http://www.machsupport.com/forum/index.php/topic,16290.msg110182.html#msg110182
Hood
Finally got round to adding this code in but then realised the high-speed spindle has no encoder so no feedback of real speed or lack of.
Maybe i need to look at a simpler fix like spindle power DRO = 0 after maybe 1s delay therefore spindle can't be running??
Not sure how to code a short delay, I guess i need to add some logic like "If M3/spindle is ON and PowerDRO=0 then fault" but needs a delay maybe to allow spindle to ramp up?
Would this be better added to the M3/M4 macros so "spindle start" -> "check spindle running" -> "ok or fail"
I will have a play when i summon the whatnots to go out in a cold shop and stand at a keyboard