PWM Vs constant current

[JerryFlyGuy]

I'm new to all this electronics stuff and by no means understanding it all. I was recommended by a user to look for constant current systems rather than purchase a PWM style system. I'm wondering if others can comment and or explain the pro's and con's of these two styles and what type of uses they would apply to. I'm looking to build a 3 axis mill which can later be increased to more [ 4-5 axis] after I'm comfortable with all things CNC. My projects would mainly be toward larger size composite molds and foam bucks for things like car hoods etc.

Also as a second question [ may not be the entirely proper thread to post in] I'm wondering about the differences between the Gecko Rex board and a cnc4pc board. It would appear that the rex has USB connectivity? Vs Parrellel? Would Mach3 tie to either of these??

I'd appoligise for being a newbie but at this point there is only one way change that!!
JerryFlyGuy

[ViperTX]

Well you have to vary something in order to vary the speed of the motor. PWM of the voltage is the best way to do it. If the current is always constant then I would say that you are running at a constant speed.

[philba]

A PWM controller has the advantage of turning the drive transistors (MOSFETS, usually) fully on or fully off. When fully on the MOSFETS present little resistance and generate much less heat than when they are partially on. This allows the controller to be much more efficient and run cooler. Cooler electronics last longer.

[pminmo]

What is the application, dc motors, stepper motors....?