" Greg - here is why it's a bad idea on a drill press - let's suppose you
are drilling away and the bit jams - it doesn't break the bit and it's
pulling on whatever you were drilling (I don't' know about you, but this
does happen to me from time to time) - if I set the stop to "coast", when
I hit stop the force stops immediately. If I set stop to "decelerate",
the force continues for the length of the deceleration time. I prefer
the former.

I have the braking set at one second, the lowest setting, but on this VFD
it seems that it will stop sooner, depending on the load, and RPM. At low
RPM, and low spindle speed on the variable it stops in way less than one
second. At 30 Hertz, about 60 RPM, and low speed it will stop in 1/2 a
revolution, or about 1/2 second. At higher speeds even on coast to stop
you have inertia to be concerned about. The way this machine reacts I
believe if the tool is jammed and the motor or spindle stalled the braking
would be instant. Keep in mind on most VFDs, if the motor is stalled, the
braking time is zero, the VFD will not continue to apply power to a
stalled motor after the stop button is pushed because the VFD sees that
the motor is stopped. I guess I don't worry much either way as my reaction
time is slow enough that what ever carnage that results from a problem
will most likely be way over before I can hit the stop button any way!
Greg O


the characteristic you report is apparently dependent on the VFD - on the
Eurotherm drive on my wood lathe, for example, it will power for the entire
ramp down time even if stalled. So, I guess the final answer is "it
depends"