I'm starting a cnc conversion on an Optimum BF46 mill and have just purchased a Kflop board to get things rolling.

Running the board off the machine, I see that the setup time between a change in the Dir signal and the falling edge of the next Step pulse is about 0.5 microseconds, whereas the stepper driver I was hoping to use requires 20 microseconds. The manual and discussion somewhere on cnczone suggests that there is not enough adjustment in the board setup to satisfy this requirement (didn't spot that little problem before ordering!)

As far as I can see, there is always at least 500 microseconds between the last Step pulse in one direction (due to deceleration) and the Dir signal changing state, so am proposing to simply delay the step signals by the required 20 microseconds. The Dir signal is constant while running fast, so top speed is not affected.

The question is-
Are there any circumstances under which an axis can reverse direction without the controller ramping the speed down to zero? It would seem to be a recipe for lost steps or a broken machine, but there might be something obscure. I know that all the other axes could be going at full speed while this happens.

Thanks in anticipation
Bob