Which kit???

[dazp1976]

Cautionary note to OP; linked BoB - if you're looking to replace the BoB, above linked item (which I also use, as do many of us) requires a separate 12-24VDC power supply - it supplies the Opto-isolators used for limit switches and e-stops. Also, for the 0-10V spindle supply, if required. This, independent from the 5V supply from the USB lead.

Just want to make sure that any decision you make is fully understood.

If you disable all the limits, stop etc though in mach etc, it's a cheap way of just testing the axis movements without needing to have a 24v supply. Just to test the KK board axis movements themselves aren't a problem.
Just don't move them to their ends.

I've never been a fan of the KK board anyway tbf.
Having everything on the same 5 volts always seemed a bit iffy to me. Especially when it came to e stop, limits, relay etc.
Everything else I see has 5v and 24v to isolate the inputs and outputs from each other.

Now I've mentioned that, that is worth ruling out. I mean the board I linked uses the 5v for the outputs and a seperate 12-24v for the inputs. Thus isolating inputs and outputs from each other

I have no VFD type spindle drive but I also have no cable sheilding and I'm using 3 axis with proximity sensors on the limits and seen no problems thus far.