Flyback diodes

Just to clarify emf's post. Bipolar using half the coil should be equivalent performance to unipolar.

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[www.hydraraptor.blogspot.com]

OK, I tried using half the coil instead of the full coil and so far it seems to have noticeably more torque! I'm trying an extrusion now to see how well it works, but so far I'm a happy camper!

Thanks guys!

Eric,
Yes, thinking about it, using half of one coil at its full rated current means your low speed torque will be about .7 what it with the original unipolar cc drives assuming they used two coils on at a time. As that was strong enough for milling it must be easily enough for FDM.

I can't remember what your original supply voltage was but if it was say 24V then your top speed is probably reduced by a factor of about 2 compared to the milling machine. Perhaps a bit less due to using one coil on at a time instead of two. Is that what you are finding?

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[www.hydraraptor.blogspot.com]

I'm not sure what the specs were for CNC milling - I only got the CNC kit once I decided to turn it into a repstrap. From the data sheet for the motors, it says 3.2V.

Eric,
Sorry, I thought you already had an existing CNC machine with drive electronics. Normally 3.2V motors would be driven from a constant current supply of 24V volts or higher to get fast rise times.

Chris

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[www.hydraraptor.blogspot.com]