Connecting 6-lead unipolar steppers (Full or half coil)?

  • Hi everyone,

    The printer that I am retrofitting utilizes 6 lead unipolar steppers, and I was wondering how I should connect them. The Duet documentation says that you can use them, but doesn't give any example on how to connect them. From what I've read, you can connect it the same way as a traditional bipolar stepper - you just ignore the centre taps. However, reading this document provides some more information. This would put the stepper into a full coil configuration, which provides greater torque, however the supplied current must be cut in half in order to keep the motor in spec (4x the ohmic heating if pushing the full current through). It also produces 4x the inductance than in a half-coil configuration, which results in reduced high-speed torque. Meanwhile in half coil configuration, the high speed torque is increased by 2x, but at the cost of higher current and heat.

    From this document, it seems to recommend a half coil configuration for any high-speed applications, and full coil for "low speed operation of high current motors whose current ratings exceed the capacity of the drive and/or power supply."

    From the document above it seems that half coil is the best option. To anyone who has experience with unipolar motors, which configuration works the best for 3d printing?

  • I always use full coil, never have drawbacks. All the machines i see works with full coil

  • administrators

    @j3d, which is best depends on the inductance of the motors and the VIN voltage. Do you have the motor specifications?

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