3D printable brushless motor

Inspiration

There is a Designer by the name of Christoph Laimer who designed a couple of 3D printed motors. I built his brushless motor V2, to be precise the model A001.1 and came to the conclusion that there were a few changes that could be made to make the motor lighter, less prone to melting and potentially more powerful. And so this motor was born. It retains pretty much the same winding as the A001.1 model but is otherwise an eintirely new design.

Some qualitative testing I did with it 

Print settings

General

• PLA is not recomended due to heating of the core
• 0.4mm nozzle and line width
• 0.15mm layer height 
• minimal part cooling for good layer adhesion 

Stator

• Print upright with the 3 mounting holes on the build plate
• use supports only on the bottom features

Rotor

• Print upside down with the 6 mounting holes on the build plate
• enable supports

Rotor Bottom

• Print right side up with the threads towards the top
• no supports needed

What you'll need to buy

• 1mm enamelled copper wire
• Magnets as described below
• 25x37x7mm ball bearings

Assembly

This design comes with two different rotors. One houses a convetional alternating magnet array. For this you'll need 12 10x3x30mm Magnets with their poles on their largest faces. The other rotor is designed to house a Halbach array. For this you'll need 12 6x3x30mm, or 24 6x3x15mm magnets, with their poles on their largest faces and 12 3x3x30, or 24 3x3x15mm Magnets, with their poles on their larger faces. 

Alternating array

Insert the magnets into the slots of the rotor with alternating polarity. To test for correct polarity, you can slowly run another magnet aroud the outside of the rotor and feel it being repelled and attracted repeatedly.

Halbach array

Insert the larger magnets into their slots as described above. The smaller magnets can then be inserted to form the below pattern of polarity

Core

The core is wound as described here for the A001.1 model. The wires can be fed through the holes on the bottom of the stator. Do feel free to add more windings as from my experience the slots can fit more.

Final assembly

With the core wound and the rotors fittet with magnets you can now asseble the motor. First, you'll want to ensure a good fit between the bearings and the printed parts. You can either adjust the fit on the printed parts, or modify the CAD model. Fit the first bearing into the rotor and make sure it's seated all the way. Fit the second bearing in the bottom part of the rotor. finally slide the core into the rotor until it fully seats in the bearing. Now you can slide on and screw in the bottom of the rotor. If the motor doesn't spin freely, make sure there are no strings, or other printing defects in the gap between rotor and stator.

Happy printing!

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