parralell port voltage.

[John S]

Hard facts of life here, no calculations but based on building over 120 cnc machines or conversions. The X3 cnc kit sold by ARC sold 58 units for a start and I'm not counting any of the Sieg CNC machines that are made by Sieg.

Hard fact is on any decent CNC stepper build the weak point is always the stepper drive, motors hardly ever go wrong unless you do something seriously bad to them.

Speed is voltage and the average stepper motor needs to run at 20 to 25 times it's nameplate voltage, as most are between 3 and 6 volts that's 75 to 150 volts. As most available stepper driver max out at 80 volts that normally determines the max. However the popular 80 volt Leadshine drivers also max out at 7.2 to 8 amps [ beware the 9.2's released , they were not reliable ]

When people read these specs they look well over spec'd for a 3.1Nm motor, which they are but as I said earlier the drivers are ALWAYS the weak link. now if you spend on these more expensive drivers and down rate you get various advantages, one is longer life because they are never stressed and always operation well with limits, never get hot, again for the same reason and you always have the correct driver for if you ever upgrade.

Do the sums, 3 expensive drivers that are the best part of bomb proof or buying cheaper ones and replacing then 2 and even three times ?

Out of those 58 X3 kits which drove 2.1Nm triple stack motors, we had 3 bad drivers and this one was from a guy who lives right next door to a power station and regularly has to replace televisions, computers etc because of spikes, as do his neighbours.
So discount this and it's a 100% success rate on machine used by users with different skill and experience levels.

Compare this to say a Route-out machine, I have often seen posts on here wanting new boards.

End of the day you get what you pay for.