makeSEA 3D Printed Brushless Motor v0 (prototype)


makeSEA Brushless Motor v0 (Prototype)

(see also, Brushless Motor v.2)

In the beginning was the word - Chris asked me to buy conductive and magnetic PLA from Proto Pasta, and I should create something useful with it. The initial experience with this materials was sobering, instead of experimenting with special material properties, I had to fight to get it through the printer nozzle (see other blogs).

The conclusion for the conductive PLA is, that it can’t be used for high power applications, only for low power like a small efficient LED. The properties of conductive PLA and its application could easily be measured by using a simple Ohmmeter. Knowing the simple formulas U = R * I or P = R * I^2 it’s very easy to predict its behavior and its application as a conductor. It is useful like a customizable resistor with a resistance larger than 1kOhm.

It’s more sophisticated to explore possible applications of the magnetic PLA. Yes, a magnet can stick to it, so it would be possible to design a door lock using a regular permanent magnet, and some magnetic PLA. The magnetic (resp. ferromagnetic) properties could also be measured, but I didn’t have a suitable instrument. Anyway if I would know such material constants, I wouldn’t be able to evaluate an application with a simple formula. Compared with regular iron, the force of magnetic PLA attracted by a permanent magnet is only moderate. Nevertheless my focus was attracted to use the material as a core for some kind of coil (no surprise - I’m an Electrical Engineer by education).

Even though the magnetic PLA was maybe useless, it started a fire: I wanted to 3d-print a brushless motor, and I wanted to create a thing, which has some extra shaft-power, not just a rotating design study.

How to realize this? Either you start with complex theories and heavy formulas, or you just create something and later carefully analyze the reasons, why it doesn't work. 3d-printing is great for trial-and-error, and (by accident) I had some spare copper wire, permanent magnets, and ball bearings: ready to go!

The initial design was similar to a regular brushless motor, which can be found in many RC-toys. The design has 9 teeth and 12 magnets (9N12P). The stator has a diameter of 40mm and a height of 20mm. The slot between the teeth was big enough to fit 8 turns per tooth with 1mm thick copper wire. The 12 magnets in the rotor are 10mm wide, 2mm thick and 20mm long (needs to match with stator height).

The stator winding scheme is very simple:

(thanks to for the great online calculator)


Now it’s time to measure the basic characteristics of the motor by using it as a generator. A simple, well known method is using a drill press and a voltmeter. Since I’m even owning a scope, I’m using this instrument to measure the RPM and the voltage:

Only 0.1V amplitude at 1’000 RPM is not ideal. OK, it’s not nothing, but it roughly means Kv = 10’000 RPM / V or in other words: when running it as motor on a 12V battery, the motor would make 120’000 RPM. No chance, that the rotor survives the centrifugal forces at this speed. It would explode, and the magnets will fly away like projectiles. Very dangerous!

Nevertheless I gave it a try, connected the 3 wires of the motor to the ESC of my child’s RC car, which runs with an 8V battery. Very gently using the throttle … nothing happens. The motor makes some beeps, it only does some minor jerky movements. Full throttle! Still nothing - only the beeps were a bit louder.

The explanations, why it doesn’t run is simple (at least for me as an Electrical Engineer).

First you need to know, how an ESC works: In order to make the motor turn, the ESC needs to power the 3 wires (the coils) in the right sequence and this generates a rotating magnetic field. The permanent magnets in the rotor will follow this rotation. If the timing is too fast, the rotor will “slip”, and not follow. In order to not slip, the ESC will wait with powering the next coil, until the rotor has turned to the appropriate angle. But how does the ESC know, where the rotor currently is? The answer is “back EMF” - only two coils are powered, and the third coil is working as a generator (similar as described above for measuring Kv). If the generated electrical signal fulfills certain criteria, the ESC switches the powered coils, and uses another coil as generator, etc.

Problem: with zero RPM, the generated voltage is also zero, and the ESC can’t measure a signal! In order to start from zero, the ESC starts “blindly” by powering the coils at a fixed, very low speed. The rotor hopefully follows, and as soon as the generated signal is strong enough, the ESC increases the speed in a well controlled manner.

Our 3d-printed motor has the problem, that Kv is by far too high: the generated Voltage is too little (ESC fails to detect a signal), magnetic forces are too little and the inertia of the rotor (heavy magnets) is too big, it can’t accelerate fast enough. Finally the motor can’t follow the “blind” startup sequence of the ESC. Even a manual impulse doesn’t help.

Conclusion: Fail!

To be clear: the design doesn’t have a fundamental bug. If the coils are connected and disconnected manually to a power source in the right sequence, the rotor follows, and rotates step-by-step. If the ESC had an even more conservative startup-procedure, it probably worked. But a special ESC isn’t my goal - the motor should run with a common ESC!

So it’s clear, that the Kv-value needs to be dramatically reduced. Or in other words, the generated voltage needs to increase a lot. The result will be a lower RPM (lower centrifugal forces) which goes along with a higher torque. Finally the ESC will be able to sense the signal of the un-powered coil.

These modifications will have the desired effect:

  • Stronger magnets
  • Longer magnets / higher stator
  • More copper wire turns
  • More teeth
  • Wires closer at magnets (field decreases depending on distance)
  • Better ferromagnetic material for stator (no choice in my case)

In order to test the effect of more turns closer at the magnets, I’ve re-designed the stator. The wire diameter needed to be decreased to 0.35mm, because more turns require more space, and space isn’t available. The new stator has 36 slots (4 times more). Teeth are only ⅓ as long as the initial stator teeth (wires closed at magnet). Winding scheme is basically simple:

The new stator was initially printed with regular PETG (not ferromagnetic), and onlyone phase was wound (with 10 turns per tooth, 1.2 times more compared with prior design). This is sufficient to check, if the new design and the windings have the desired effect.

The stator height is still 20mm in order to reuse the existing rotor with the 2mm magnets. The overall improvement factor was theoretically 4*3*1.2 = 14.4 divided by an unknown factor due to the non-ferromagnetic PETG. It’s time for the trouth - connect to drill, and measure with scope:

The effect is clearly visible: 1V amplitude at 1’000 ROM, roughly Kv 1’000. Numbers would be even better if the magnetic PLA was used. Great! :-) … And we can estimate that the magnetic PLA amplifies the magnetic field by a factor around 1.4.

Only drawback is the cross-section of the copper wire. The resistance of a single coil is 1.3 Ohm. That’s a killer: at 3A load, the power loss over the coil is 12W, which finally results into heat. With all 3 coils in action, the motor produces heat with 36W. That’s like the power of an average soldering iron. Too much for a PLA core! The motor would melt.

Anyway, the actions had the right effect, we’re on the right track.

The final changes affect the whole motor: 3mm thick magnets (maybe 1.5 times stronger), 30mm long magnets (higher stator, 1.5 times longer), and use magnetic PLA for the stator (1.4 times better). With 0.67mm copper wire diameter, it is possible to make only 3 turns per tooth (3.3 times worse). The reduced number of turns is hopefully compensated by the other improvements. Kv of this motor will theoretically change by a factor of 1.5*1.5*1.4/3.3 = 0.95

In-deed the final changes were the successful formula. The first 3d-printed brushless motor, running on a common ESC was born. And the motor deserves it’s name as a motor: with 35W and 60% efficiency it has enough power to drive a demanding application.

The motor is named “makeSEA Model A001” and described in a separate article.

0 Attachments
Average (0 Votes)
Please sign in to comment.
Posted on 7/16/19 3:20 PM. if some one have it plz i need to make this motor
Posted on 7/16/19 3:21 PM.

Check Out the makeSEA Mash Market® for a collection of useful designs related to this Wiki article.

Enabling AR, mixed reality and 3D content for everyday use.SM


for Architecture
& Design
Magic Leap &
AR/Mixed Reality
Content Publishing
for Education
& Making


for Construction
for Trade Shows
& Exhibits
for Retail
& Branding

Easy Augmented Reality

makesea for Augmented Reality (AR) is a SaaS that supports a number of verticals and at the core is a content management platform that can be dressed for any experience from consumer branding...

AR and 3D Printing Should be Part of Advanced Curriculums

makeSEA for Education provides a safe, secure environment for students to collaborate and iterate on 3D designs and projects. Our SaaS platform also offers a way to get started with Augmented...

Using AR for EDU

      It’s no secret that keeping the attention of today’s students is harder than ever. From grade school to college level, these students have been raised with...

Some AR Stats to Think About

Download the infographic . If you think Augmented Reality/Mixed Reality is still just something to think about, think again! This technology is being used in everyday businesses...

makeSEA selects Magic Leap as headset of choice

  An estimated 75% of adults use glasses or some sort of vision correction, according to the Vision Council of America. But this is just one of the reasons makeSEA has chosen Magic...

Collaborate with makeSEA Curate™ App

Legitimate use cases for Augmented Reality (AR) are many and varied. It can be used in so many industries to assist and improve workflow processes. AR gives an individual or a group the...

Augmented Reality for Manufacturing

Manufacturing may well be the vertical where Augmented Reality (AR) is currently being used and accepted most frequently. That’s not surprising if you consider that so much of the...

Augmented Reality for Sales & Marketing

In the last blog we talked about the use of Augmented Reality (AR) and the real-world use cases, primarily pertaining to service related industries and industries with a service component, such...

Augmented Reality Improves Business Processes

In past blog posts we’ve talked about real-world uses for Augmented Reality (AR). The thing is, too many business people are still under the impression that AR use cases are some...

This Changes Everything

VR (Virtual Reality), AR (Augmented Reality), mixed reality, spatial computing—this is technology that is changing the way we do business. Companies are rapidly adapting to and using these...

AR as a Reference and Training Tool

Augmented Reality (AR) is poised to bring dramatic changes to everyday life, so its not hard to imagine that it is already impacting the workplace. AR technology dates back to the mid-1990s,...

AR and Your Trade Show Booth

No matter what industry you are in, your trade show booth and the image you present is your show piece and influences the perception others have of your company and brand. In the trade...

Architecture, Design and AR

Recently I made a move to another state and in the process decided to have a small house built rather than rent or buy something I would need to put significant money into immediately. The...

Enhance Your 3D Print Program

As 3D printing is evolving it is pretty much mainstream coursework in institutions of higher learning. The departments of engineering, architecture, fine arts, and medical have incorporated...

Embrace Change

Change can sometimes be difficult and a little intimidating but the use of augmented reality as part of your marketing, sales and even training efforts is rapidly becoming main stream. One...

This is why we share our designs!

We recently heard from Manes Cabanas, Associate Professor at the Universidad de Oviedo in Spain. He has used the makeSEA brushless motor as a teaching tool for his students in Electrical...

makeSEA R&D

makeSEA is more than a service, it's a platform for Digital Transformation. Here's a hint at whats coming . . .

makeSEA Proudly Sponsors Construct3D 2018 Conference at Georgia Tech

We are thrilled to be proud sponsors at the 2018 Construct3D conference for 3D Printing in Education at GATech in Atlanta this coming weekend! Come visit and see me, Chris Stavros, Chief Maker...

Is 3D printing good or bad for construction jobs?

(Quartz/Mike Murphy) Now You can now 3D-print a house in under a day   I love this discussion thread  about the recent article by Mike Murphy at QUARTZ  on 3D...

Move over Moore . . . there's a new law in town!

illustration by ZOHAR LAZAR According to this article by Clive Thompson of WIRED Magazine , there is a new law in town:  Lass' Law.  Moore's law has accurately predicted...