Stepper - ballscrew loading

[Jonathan]

Over the weekend i will be loading my gantry (in lbs) in the middle to measure the deflection and too see if it needs more work, so i needed a guide weight to go by.

I'd be wary of using the Z-axis to do that as unless you have something to measure the force, such as putting bathroom scales underneath the Z-axis, you could seriously damage something - 2262N is 508lb.f.

my 3nm nema23 on 70v (good guess there) may be replaced with a nema 34 but ive not decided which one yet.

How much does your Z-axis weigh, just the bit that moves up and down so we can work out the motor and driver? It'll be quite a lot with the spindle and motor you're planning on, but generally such high speed isn't required on the Z-axis anyway.