modifying the cheap stepper motor Howard Ind. 1-19-4200 from unipolar motor to bipolar

From time to time NEMA17 stepper motors from Howard Ind. are sold very cheap at places like ebay or pollin.de for as low as 1 or 2€.

A few months ago I got a bunch of Howard 1-19-4200 motors at pollin.de and wondered if they can be used for building a Prusa.

The short answer is:
- For the Z-axis: yes, they are perfectly suitable.
- for X and Y it depends on your setup, but in any case you will be limited to slower movements. Better accept to spend money on bigger motors.
- for the extruder: no, hopeless.

The motors are unipolar motors, but with some not-so-diffcult internal modifications they can be changed to bipolar.


I compiled a report on the needed modifications here: [makr3d.de]

I hope this proves to be useful for somebody here,

Michael

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Quote
tenbaht
- for the extruder: no, hopeless.

Did you test it before or after the modification?

IIRC, with ferrite core steppers, you have to put an iron ring around the rotor when pulling it out of the stator to maintain high magnetic flux, otherwise the stator will permanently lose some of its magnetization, leading to reduced torque.

Edited 2 time(s). Last edit at 11/04/2013 06:41PM by ansel.