Hi,
you will never know until you measure the inductance.
Do you have an LCR meter?
High inductance does not mean low or lower quality, but it does mean severe speed limitations which is of particular importance in CNC machines.
The same high inductance motor which misses and stalls at the slightest provocation but could still be a top candidate for a telescope positioning
motor say.
All steppers lose torque the faster they go, that's the physics of how they work. Inductance is a good measure of how bad that torque degradation
will be. A 500oz.in stepper but 8mH will be lucky to have 5% (25oz) of its torque at 1000rpm while a 300oz.in stepper but only 1.2mH will
have 40% (120oz.in) at 1000rpm. First time buyers are likely to go for the higher torque unit, but at speed the lower torque unit, with very low
inductance, will far outperforms it.
The classic way to mitigate the loss of torque with speed is to use the highest voltage drivers and power supply you can. At the current time there
is a good selection of good to excellent quality 80VDC drivers at fair prices. If you want to get your steppers to perform at speed, doesn't matter
what steppers, then get some 80VDC drives and a 80V supply.
Craig