Printable BLDC Motors

Ok

I have been musing on this one for some time. Having bought a outrunner type BLDC and stripped it down to have a look at it, I was quite amazed at how simple they are.

Arguably more simple than a brushed DC motor.

Perhaps even simple enough to print......

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Necessity hopefully becomes the absentee parent of successfully invented children.

BLDCs are basically permanent magnet AC synchronous motors with a trapezoidal current profile rather than sinusoidal- in the few where this aspect has been given any attention.

They closely resemble stepper motors with maybe 12 steps per rev, and 3 coils in a delta or wye configuration instead of two separates.

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Wooden Mendel
Teacup Firmware

Yup, sort of.

Certainly close enough for the purposes at hand. Given that they are mechanically simpler than a stepper though (as you pointed out less poles) they should be easier to make.

Particulalry the out-runner style.

I have a cheapish one I bought in to dismantle and there is very little to them electro/mechanically.

Certainly the plastics are printable and the out-runner could be made from cheap steel pipe section.

The benefits of the out-runner are that they generate more torque and the magnets are constrained against centrifugal force by the steel pipe section.

Minaturisation is'nt really an issue for what we are trying to achieve motors that are of a reasonable size with good torque are what we want.

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Necessity hopefully becomes the absentee parent of successfully invented children.

you can avoid using magnets . you can avoud using any steel or ferro. The price is bad torque. All you neeed is (copper) wire and plastic (printable) frames.

It is good idea to make one!

Rotor and stator will both consist of wire coils. Wire on plastic frame. That is all. So we need brushes to power rotor. Brushes may be commutating (usual DC) or not commutating (just two rings) - but at this case you need smart controller to swith fazes.

First thing you could print is a small handy reel machine to make coils.

Yes I have been thinking about coil formers and counters that I could put on my mini-lathe.

The weak part of DC motors (or universal motors) is the brushes. I guess this is specificaly why I was thinking along the lines of BLDC's ie, Brushless DC. Alignment, metarials and reliability are all issues with brushed motors.

Electronic commutation is reliable, fast and has a side benefit of producing a useful degree of position & speed sensing.

Copper these days is expensive, steel is cheap and permanent magnets are farily common.

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Necessity hopefully becomes the absentee parent of successfully invented children.

Hi All,

I started a wiki review article on Actuator Fabrication that you might be interested in:
[www.reprap.org]

Many of you will be familiar with most of the information, but I would wager that even the most grizzled old replicators among you might find something new.

Please visit and add your own contributions!

-Matt

Nice bit of work, Matt, and nice body of work.

... You realize that now I'm going to have to set aside a few hours and read all this stuff.

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!