Nema17 torque after dissasembly

Measure stepper motor torque

Thomas

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Description

See this youtube video for inspiration: https://youtu.be/A4WZm45XJ84

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%).

Details

Motor	A	B	C
Winding resistance	3.3	3.4	3.4
Inductance (phase A / phase B)	5.1 / 5.1 mH	5.0 / 5.1 mH	5.2 / 5.3 mH
Maximum weight at 0.75A (1 phase)	176 / 177 g	174 / 176 g	176 / 177 g
Maximum weight at 1.0A (1 phase)	218g	218g	218g
Maximum weight at 1.0A (2 phase)	325g	323g	319g
Motor disassembled + reassembled 1.0A (2 phase)	320g
Motor disassembled for 24hrs	319g

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.

Components

1 × MS17HD4420 nema17 stepper motor

Project Logs

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Motor specifications
Thomas • 03/28/2021 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
Thomas • 03/25/2021 at 04:45 • 0 comments

Internal construction of stepper motor (source):

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.