Nema17 torque after dissasembly

Measure stepper motor torque

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Nema17 motor maximum holding torque was measured, stepper motor disassembled, then re-assembled. Torque was measured again, no significant difference was seen, at most maybe a very small loss (sub 2%).

Winding resistance
Inductance (phase A / phase B)
5.1 / 5.1 mH
5.0 / 5.1 mH5.2 / 5.3 mH
Maximum weight at 0.75A (1 phase)176 / 177 g
174 / 176 g176 / 177 g
Maximum weight at 1.0A (1 phase)
Maximum weight at 1.0A (2 phase)
Motor disassembled + reassembled 1.0A (2 phase)

Motor disassembled for 24hrs

Weight was suspended 10cm from center of axle.

r = 0.1m
F = 320g = 3.14N

Torque = rFsinθ = 0.31 Nm

Motors are very consistent to their specifications, even though they were built years apart.

  • 1 × MS17HD4420 nema17 stepper motor

  • Motor specifications

    Thomas03/28/2021 at 22:05 0 comments

    Motor PN: MS17HD4420

    4 = 34.3mm length

    weight = 225g (slightly higher than MS17HD4P4100)

    Torque should be about 0.33Nm.

    "420" is the winding current rating but its not clear what this would be, somewhere between 1.0 and 1.5A. Probably closer to 1A.

  • Stepper construction

    Thomas03/25/2021 at 04:45 0 comments

    Internal construction of stepper motor (source):

    Basic Structure

    Known as "hybrid stepper motor".

    Front and rear rotor cup sandwich a permanent magnet, which should hold the magnetic field in the laminations. Perhaps older stepper motors did not have this magnet and were more susceptible to field loss.

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Voja Antonic wrote 03/30/2021 at 16:36 point

I like the experiment. I have witnessed dramatic torque loss after reassembly, but I never performed my own experiments. This was interesting to see.

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