
How to print an electric motor - tomcam
https://spectrum.ieee.org/geek-life/hands-on/how-to-print-an-electric-motor
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jdietrich
On a similar note, Fishman produce a range of electric guitar pickups that use
stacked PCBs for the sense coil, rather than the traditional loop of enamelled
copper wire. It's not necessary (and it's undoubtedly more expensive), but it
gives them far more precise control over inductance.

[https://www.youtube.com/watch?v=oZSS13d3vZs](https://www.youtube.com/watch?v=oZSS13d3vZs)

[https://www.fishman.com/products/series/fluence/](https://www.fishman.com/products/series/fluence/)

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unwind
Uh ... cool! He says "48-layer circuit board", so my initial guess is those
are not super-cheap, no. I think a regular PC motherboard (which is not a very
simple board) has 8-10 layers. 48 is a lot.

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iamleppert
Another cool video of a high performance 3D printed halbach array brushless DC
motor:

[https://youtu.be/YsSm65DAcCg](https://youtu.be/YsSm65DAcCg)

The author posted up all his design files and has extensive documentation and
instructions.

(Note that most of the housing is 3D printed while you still need bearings,
coil and magnets etc). But still very cool what is possible and opens endless
customization opportunities.

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jacquesm
Very neat. I wonder how the small magnets are retained when the rotor is
stationary. The big ones slide in but the small ones are just pushed into
place. Once the whole thing is moving they get pushed out but when it isn't
moving the stator will suck them in.

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eschutte2
I'm assembling this right now, and the stator doesn't pull them out - it seems
like the magnets on either side help keep them in place.

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quackerhacker
> "I’ve been able to almost double it by adding a ferrite sheet to the back
> side of the stator coils to contain the coils’ magnetic field lines."

I never heard of a ferrite sheet, completely awesome! I liked the article, but
IMO the title is a little misleading. What I gathered is that he 3d printed
the rotor only. I'm assuming the actual 4 layer pcb was etched. The rotor was
still wound manually. The hall sensor still soldered by hand.

The _print_ notion implies production automation, which is my only gripe. His
hackaday has a more accurate title "PCB Motor".

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zan2434
doesn't PCB stand for "Printed Circuit Board"? So it's still mostly printed..
The rotor is 3d printed, and the stator is manufactured via PCB techniques. I
understand what you mean regarding it not being totally printed though.

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TaylorAlexander
While “PCB” does mean “Printed Circuit Board”, it’s kind of a misnomer. The
word “printed” doesn’t really accurately describe the process used to make
PCBs.

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jdietrich
They're standard printing techniques, just not "squirt something out of a
nozzle" printing. With the exception of drilling and through-hole plating, the
processes used in PCB manufacture would be entirely familiar to any
experienced printer.

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macromaniac
There's also a related but different type of pcb motor that relies on the
piezoelectric effect instead of magnetism:
[https://www.youtube.com/watch?v=uFZsH62ewYo](https://www.youtube.com/watch?v=uFZsH62ewYo)

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daveguy
Fascinating motor design. I wonder how much torque is lost using a hall sensor
vs backemf. It is my intuition that backemf would be more precise than hall
sensor, but I don't know much about motor design. Would it be worth adding
circuitry to amplify the backemf signal?

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pankajdoharey
I doubt the claim that printing a coil on PCB is cheaper than winding wire
coils. At any rate you have to print the design on PCB , etch it join those
double side PCBS. It cannot be cheaper.

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iamleppert
You can build a coil winding jig to automate the winding process too..

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pankajdoharey
Yup absolutely, plus the amount of conductor you can use is limited on a PCB.
It is cool but not cheaper.

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amelius
Instead of using permanent magnets, why not create two PCBs which rotate wrt
eachother?

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mrfusion
That’s actually a really big deal, right? If we can 3d a motor were way closer
to a self replicating 3d printer.

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petermcneeley
The only thing actually 3d printed here is ridged container for holding the
permanent magnets in place. PCB electromagnets are not new and multilayer
interconnect PCB boards have been around for 30 years. A real 3d printed
electric motor would be quite a feat indeed.

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zeta0134
That has me wondering if kind of a hybrid solution could work, like a 3D
printer that can also pick and place components mid-print. That could be a
reliable way to deal with the permanent magnets, since presumably there isn't
going to be a way to print out any material that would magnetize itself
reliably.

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mrfusion
I think there’s a way to make motors without permanent magnets

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petermcneeley
Indeed. An electromagnet is a magnet! However usually these are quite weak
even with iron cores.

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jacquesm
Quite weak? Electromagnets can be as powerful as you want in a given space
provided you can cool them and you can avoid saturating the core.

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petermcneeley
I more mean in reference to using them as an opposing magnetic field for using
in an electric motor. Like suppose he simply put two PCB electromagnets
together. What would you expect the force to be?

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jacquesm
I'm sorry I read your comment as a general statement on electromagnets. Yes,
two PCB based electromagnets are not going to be able to make a very dense
magnetic field. The major reason is that the current carrying capacity and
cooling will be lousy. But a sizeable electromagnet made from a copper coil
and a half decent core material will happily lift your car.

