Specs of PS MTDH31NR... steppermotor needed

[TechGraphix]

Who knows the specs of this stepper:
Pacific Scientific MTDH31NR-HTLNF-NS50
I can't find any details except it is Nema 34
The machine is build in '98 so the steppers are older..
Although the current is set to 5A they can be turned between thumb and finger.. seems quite weak to me but i want to be sure befor i replace them..

Kind regards
Kees

[James Newton]

I also was unable to find any specs for that motor, but this page:
techref.massmind.org/techref/io/stepper/wires.htm has a number of methods for figuring out the correct wiring, which might help.

[TechGraphix]

Thanks James, but it's not the wiring that interests me but things like Holding torque, Induction, Resistance etc. And all parameters that could tell me why these motor appear so weak or they should be very powerfull instead...

Kees

[James Newton]

Resistance is easy to measure with an ohmmeter. Inductance is a tad more difficult, but can be done:
techref.massmind.org/techref/inductor/measure.htm

Holding torque fairly easy to measure, techref.massmind.org/techref/io/stepper/measure-torque-rb.htm
but it depends on the driver, as well as the motor.

In this case, I would just follow the techniques in the link above, using a variable voltage power supply to provide increasing voltage (and so current and so power) to a pair of coils until the motor started to get hot (increase /slowly/ to give the motor time to warm) and then see what weight it can hold. Once you know what current it can take, switch to a current regulating driver, like the Gecko (more than 2 amps) or Linistepper (up to 2 or maybe 3 amps), and see what sort of torque you can get at speed.