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PCB Motors Hack Chat Transcript

A event log for PCB Motors Hack Chat

Carl Bugeja will be joining us in the Hack Chat to talk about making PCB Motors!

Stephen TranovichStephen Tranovich 5 days ago0 Comments

Stephen Tranovich12:05 PM
Okay, let's get this chat started!

Arsenijs12:05 PM
Yay!

Stephen Tranovich12:05 PM
A big welcome to @Carl Bugeja for joining us on the chat today to talk about their PCB Motor designs!

Carl Bugeja12:05 PM
Thanks for having me

Stephen Tranovich12:05 PM
@Carl Bugeja , kick us off by telling us a little bit about yourself!

Carl Bugeja12:07 PM
So my name is Carl Bugeja. I'm a 23yr old electronics engineer, graduated from uni 2 yrs ago and since then i've been trying to build cool robots

Stephen Tranovich12:09 PM
Sounds like the dream to me.

Stephen Tranovich12:09 PM
Our first question comes from @Lutetium : Where did the inspiration for your PCB Motor design come from?

Carl Bugeja12:09 PM
I had this drone startup were we were trying to design a very tiny coaxial drone.. we have failed because we were trying to use off-the-shelve parts to integrate it into our drone.. after this i had come up with the brsuhless pcb motor concept were i was aiming to combine the prop, stator and electronics driver into one unit

Carl Bugeja12:10 PM
Haha i guess that answers the question

Stephen Tranovich12:11 PM
Hehahe It totally looked like you were the fastest typer on the planet!

Carl Bugeja12:11 PM
this is the drone

Carl Bugeja12:11 PM

Stephen Tranovich12:12 PM
Wow, awesome! I see the PCB Motor in there. Any videos of it flying?

Frank Buss12:13 PM
doesn't look like it can fly stable with only 2 rotors, e.g. the Tiny Whooper has 4

Carl Bugeja12:14 PM
this was actually before i came up with the idea of the pcb motor.. so this robot has an off-the-shelve brushless motor.. It had four tiny flaps that control the roll and pitch axes but that's were we failed as the flaps were too small to create a strong enough force to move the drone

Rebecca E. Skinner12:15 PM
You just very precisely identified the design problem, so isn't that fixable ?

Carl Bugeja12:16 PM
at that time we had given up.. this robot weight under 30 grams and it was very hard to go lower than that

Frank Buss12:16 PM
only one prop? the whole thing must spin like crazy :-)

ꝺeshipu12:16 PM
the duct has a second fan in it

ꝺeshipu12:17 PM
if you look closely

Carl Bugeja12:17 PM
no it has two props rotating in opp direction to control the yaw.. this is the pcb as you can see it is really packed and that dual brushless motor driver in the middle inspired me to try and design the pcb motor

Kris Winer12:17 PM
Are pcb motors more efficient than off-the-shelf brushless motors?

Carl Bugeja12:18 PM

Boian Mitov12:18 PM
the magnetic fields of the 2 solenoids will not interfere when they are so closely packed?

Boian Mitov12:19 PM
I mean on the PCB dial motor design

Carl Bugeja12:19 PM
my current prototype of the pcb motor is coreless so you cannot actually compare it with the off-the-shelved ones as they have an iron core.. so efficiency-wise it is not but it is much smaller and cheaper to assemble and manufacture

Stephen Tranovich12:20 PM
Where has the design of the PCB Motor left this tiny drone project?

Stephen Tranovich12:21 PM
And then we'll hop into some more community questions, because we have some juicy ones waiting.

Kris Winer12:21 PM
Please show us what a pcb motor looks like and describe how it works...

Stephen Tranovich12:21 PM
@Kris Winer here is the project page for the PCB motor: https://hackaday.io/project/39494-pcb-motor

Kris Winer12:22 PM
Thanks!

Stephen Tranovich12:22 PM
You're welcome!

Stephen Tranovich12:23 PM
Okay, the next question is by @Jarrett : Ever consider doing a multi-pcb stackup? Or aluminum substrate?

Danny FR joined  the room.12:24 PM

Carl Bugeja12:24 PM
So in this startup drone project, i was not alone.. but i was responsible for the hardware design. After this drone project has ended, i started working alone on the pcb motor which is made for 4/4mil 4-layered pcb coil traces! After seeing that it actually worked (i had no idea if it was going to) i started working on seeing the feasibility of adding a propeller to the rotor.. but with the prototype that i have now the dynamic torque is not strong enough to go at higher speeds

Carl Bugeja12:25 PM
Hi @Jarrett my pcb motor is actually made from 4-layers and i have also tested some ferite matterial to try and improve the static torque.. it was almost doubled

Stephen Tranovich12:27 PM
@Jarred also asks: What software do you use? How do you easily draw the coils?

Frank Buss12:28 PM
maybe use higher voltage for a stronger field, but could be difficult without a core

Carl Bugeja12:31 PM
Ok so this is one of the questions i get asked alot. So when starting designing this thing i limited my design to 16mm diamter (because this was this smallest off-the-shelve brushless motor avaible) . To do that eahc coil only had a 5mm diameter area so i had to use the smallest clearances that the manufacturer could support to fit as many turns as possible. Keep in mind that i had two vias in the middle. So I traced around them by drawing a dxf file and then exported each layer drawn into my pcb software

Carl Bugeja12:32 PM
@Frank Buss delta configurations can also be used rather than a start

ꝺeshipu12:32 PM
.oO( have a small metal core sunken into the PCB in the middle... )

Carl Bugeja12:34 PM
to put a piece of metal in the middle the coils need to be substantially larger which increases the overall size of the motor, but i am going to test it out

Carl Bugeja12:34 PM

Stephen Tranovich12:35 PM
Nice! EXPERIMENTS!

Carl Bugeja12:35 PM
this is just for testing the coils and their magnetic fields

cruz.monrreal joined  the room.12:35 PM

Stephen Tranovich12:36 PM
Project fodder is from @Jarrett : You could draw coils with a hole in the centre, and then use many PCBs stacked up with a tube through them as a coilgun, yeah?

Kris Winer12:36 PM
Do the coils extend through all four layers? I mean do you have 4x the apparent coil length/area?

Boian Mitov12:36 PM
How many layers are those boards (I mean the layers with coils on them)

Frank Buss12:36 PM
Once I wrote a library to calculate magnetic fields with CUDA ( http://www.frank-buss.de/magnetfeld/ , the client for which I wrote it, allowed me to release the library as open source), maybe would be useful to simulate different configurations. My library can't emulate a metal core, but I guess there are good programs out there already which can do this, with finite element analysis etc,, so you could even predict the torque before building it.

cruz.monrreal12:36 PM
@Carl Bugeja Have you looked at using/know about planar transformers?

Carl Bugeja12:38 PM
@Jarrett Yes you can see the picture above.. not sure about the coilgun though (it was defintly the number one thing requested with my linear pcb motor)

Carl Bugeja12:39 PM
@Kris Winer Their is only one coil which current goes through one layer after the other

Carl Bugeja12:39 PM
@Boian Mitov 4-layers

Boian Mitov12:40 PM
More layers should improve it right ? ;-)

Kris Winer12:40 PM
So in effect, you have 4x the coil area then? You could then try 6- and 8-layer pcbs to increase the field strength...

Frank Buss12:40 PM
or you could just stack multiple 4 layer PCBs

Carl Bugeja12:41 PM
yes more layers and thinner pcbs should make it better

Cruz Monrreal II12:41 PM
I would imagine heat dissipation starts becomeing an issue tho, right?

Carl Bugeja12:41 PM
6-layer pcbs are far more expensive though (not ideal for prototype testing)

Kris Winer12:41 PM
I think the field strength increases with area and decrease with volume.

Carl Bugeja12:42 PM
@cruz.monrreal my current prototype is going up to 70degrees celsius @ 5v which is not that bad

Paul Stoffregen12:42 PM
yup, 6 layer = crazy expensive ... when you're used to OSH Park ;)

Stephen Tranovich12:43 PM
@Carl Bugeja can you tell us about your linear PCB motors and flexible actuators?

Frank Buss12:43 PM
2 layers, 0.6 mm thick, are not too expensive, couldn't you just stack like 10 of it?

Boian Mitov12:44 PM
the thickness will weaken the magnetic field

Boian Mitov12:44 PM
you want the coils packed as close to the magnet as possible

Boian Mitov12:44 PM
another option is 2 boards on both sides of the magnet :-D

Meek The Geek joined  the room.12:47 PM

Carl Bugeja12:48 PM
@Stephen Tranovich so after designing my brushless pcb motor (and getting over the idea that i cannot use it for my drone project) i started looking into coil actuator and thought it would be interesting to make an coil array to actuate some small magnets on it. My first try was the linear pcb motor which was pretty cool. BUT then i decided to try to get the same design but on a flexible pcb. I was not sure if this was going to work because i had to reduce to two layer (because 4 layers flex pcbs are to expensive) so i was afraid that the coils would heat up to much given that the number of turns was reduced by half

Carl Bugeja12:49 PM
But the thinner dielectric had helped in improving the coupling that luckyly enough the flex pcb actuator only goes up to 76 deg celsius @ 5v. So its smaller resistance can be at lower voltages, like a 1 cell lipo

Carl Bugeja12:50 PM
this the project

Carl Bugeja12:52 PM
@Boian Mitov I have tried testing two-pcb-one-rotor and one-pcb-two-rotors but it barely had any effect

Stephen Tranovich12:54 PM
@Boian Mitov is asking everyone's favorite question: What is the coolest Robot that you have built?

Carl Bugeja12:54 PM
Haha

Carl Bugeja12:55 PM

Carl Bugeja12:55 PM
this was actually my final-year engineering project

Carl Bugeja12:55 PM
a four-legged hybrid coaxial drone

Boian Mitov12:56 PM
Wow... Did this thing really fly? Or just for better traction on vertical surfaces?

Carl Bugeja12:56 PM

https://hackaday.io/project/39427-flypod

HACKADAY

FlyPod

Back in 2015, I pitched this concept for my final year engineering project. My goal was to design a four-legged robot which can both walk and hover. It has a coaxial ducted rotor in the middle and the rest of its weight is in the legs.

Read this on Hackaday

Stephen Tranovich1:00 PM
Wow, that's a really cool robot.

Carl Bugeja1:00 PM
It could generate enough trust for hovering. For my project I needed to design the electronics and 3d printed parts to have the first prototype platform. I was planning on continuing this project after my thesis but then ended up shelving the idea because the battery life was too poor. I have tried redesigning it but the battery still is a problem so it not worth investing so much time in the flight controller, as it is very complex to control the robot (also with the legs) in flight - at least that was the concept.

Stephen Tranovich1:01 PM
What a fun note to end on!

Stephen Tranovich1:01 PM
With that

Stephen Tranovich1:01 PM
We've reached the end of this week's Hack Chat

Kris Winer1:01 PM
Thanks Carl and Stephen!

Stephen Tranovich1:01 PM
A BIG thank you to @Carl Bugeja for coming on and sharing your great projects with us!

Carl Bugeja1:01 PM
Thanks for having me! Its been really fun

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