This Tiny Motor Is Built Into A PCB

January 24, 2018 by Dan Maloney 53 Comments

Mounting a motor on a PCB is nothing new, right? But how about making the PCB itself part of the motor? That’s what [Carl Bugeja] has done with his brushless DC motor in a PCB project, and we think it’s pretty cool.

Details on [Carl]’s Hackaday.io page are a bit sparse at this point, but we’ve been in contact with him and he filled us in a little. The PCB contains the stator of the BLDC and acts as a mechanical support for the rotor’s bearing. There are six spiral coils etched into the PCB, each with about 40 turns. The coils are distributed around the axis; connected in a wye configuration, they drive a 3D-printed rotor that has four magnets pressed into it. You can see a brief test in the video below; it seems to suffer from a little axial wobble due to the single bearing, but that could be handled with a hat board supporting an upper bearing.

We see a lot of potential in this design. [Carl] mentions that the lack of cores in the coil limit it to low-torque applications, but it seems feasible to bore out the center of the coils and press-fit a ferrite slug. Adding SMD Hall sensors to the board for feedback would be feasible, too — in fact, an entire ESC and motor on one PCB could be possible as well. [Carl] has promised to keep the project page updated, and we’re looking forward to more on this one.

For a more traditional approach to printed motors, check out this giant 3D-printed BLDC.

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It’s An Angle Grinder! No, It’s A Floor Sander!

August 18, 2017 by Dan Maloney 21 Comments

Faced with the potentially arduous task of sanding a wood floor, what would you do? Hire a pro? Rent the proper tools and do it yourself? Perhaps even shell out big bucks to buy professional grade tools? Or would you root around in your junk pile and slap together a quick and dirty floor sander from an old angle grinder?

That’s what [Donn DIY] did when looking at the wide expanse of fresh floorboards in his new sauna. Never one to take the easy way out, and apparently with a thing for angled gear boxes, [Donn DIY] took the guts out of a burnt-out angle grinder for his impromptu floor sander. A drill attached to the old motor rotor provides the spin, and a couple of pieces of scrap wood make the platen. Sandpaper strips are clamped between the discs, and as seen in the video below, the whole contraption does an admirable job.

We’ve seen lots of angle grinder hacks before, some useful, some silly. This one gets the job done and is a nice quick hack that speaks to the value of a well-stocked junk pile.

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3D-Printed Turbine Rotary Tool Tops 40,000 RPM

July 3, 2017 by Dan Maloney 38 Comments

For your high speed, low torque needs, few things beat a rotary tool like a Dremel. The electric motor has its limits, though, they generally peak out at 35,000 rpm or so. Plus there’s the dust and the chips to deal with from whatever you’re Dremeling, so why not kill two birds with one stone and build a turbine-driven rotary tool attachment for your shop vac?

Another serious shortcoming of the electric Dremels that is addressed by [johnnyq90]’s 3D-printed turbine is the lack of that dentist’s office whine. His tool provides enough of that sound to trigger an attack of odontophobia as it tops out at 43,000 rpm. The turbine’s stator and rotors are 3D-printed, as is the body, inlet scoop, and adapter for the vacuum line. A shaft from an old rotary tool is reused, but a new one could be turned pretty easily. The video below shows the finished tool in action; there’ll no doubt be objections in the comments to ingesting dust, chips, and incandescent bits of metal, but our feeling is that the turbine will hold up to these challenges pretty well. Until it doesn’t, that is.

We like [johnnyq90]’s design style, which you may recall from his micro Tesla turbine or nitro-powered rotary tool. He sure likes things that spin fast.

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3D-Printed Halbach Motor Part Two: Tuning, Testing

June 30, 2017 by Dan Maloney 8 Comments

Building your own Halbach-effect brushless DC motor is one thing. Making sure it won’t blow up in your face another matter, and watching how [Christoph Laimer] puts his motor to the test is instructive.

You’ll remember [Christoph]’s giant 3D-printed BLDC motor from a recent post where he gave the motor a quick test spin. That the motor held together under load despite not being balanced is a testament to the quality of his design and the quality of the prints. But not wishing to tempt fate, and having made a few design changes, [Christoph] wisely chose to perform a static balancing of the rotor. He also made some basic but careful measurements of the motor’s parameters, including the velocity constant (Kv) using an electric drill, voltmeter, and tachometer, and the torque using a 3D-printed lever arm and a kitchen scale. All his numbers led him to an overall efficiency of 80%, which is impressive.

[Christoph] is shipping his tested BLDC off to the folks at FliteTest, where he hopes they put it to good use. They probably will — although they might ask for three more for a helicarrier.

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Hand-Wound Brushless Motors Revive Grounded Quad

June 6, 2017 by Dan Maloney 33 Comments

You’re happily FPVing through the wild blue yonder, dodging and jinking through the obstacles of your favorite quadcopter racing course. You get a shade too close to a branch and suddenly the picture in your goggles gets the shakes and your bird hits the dirt. Then you smell the smoke and you know what happened – a broken blade put a motor off-balance and burned out a winding in the stator.

What to do? A sensible pilot might send the quad to the healing bench for a motor replacement. But [BRADtheRipper] prefers to take the opportunity to rewind his burned-out brushless motors by hand, despite the fact that new ones costs all of five bucks. There’s some madness to his method, which he demonstrates in the video below, but there’s also some justification for the effort. [Brad]’s coil transplant recipient, a 2205 racing motor, was originally wound with doubled 28AWG magnet wire of unknown provenance. He chose to rewind it with high-quality 25AWG enameled wire, giving almost the same ampacity in a single, easier to handle and less fragile conductor. Plus, by varying the number of turns on each pole of the stator, he’s able to alter the motor’s performance.

In all, there are a bunch of nice tricks in here to file away for a rainy day. If you need to get up to speed on BLDC motor basics, check out this primer. Or you may just want to start 3D printing your own BLDC motors.

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Old Motor Donates Rotor For Coaxial Wind Vane And Anemometer

January 12, 2017 by Dan Maloney 9 Comments

Problem: build a combined anemometer and wind vane where the pivots for both sensors are coaxial. Solution: turn an old universal motor into a step-wise potentiometer for the wind vane, and then pull a few tricks to get the whole thing assembled.

We have to admit that when we first saw [Ajoy Raman]’s Instructables post, we figured that he used a universal motor to generate a voltage from the anemometer. But [Ajoy]’s solution to the coaxial shafts problem is far more interesting than that. A discarded universal motor donated its rotor and bearings. The windings were stripped off the assembly leaving nothing but the commutator. 1kΩ SMD resistors were soldered across adjacent commutator sections to form a series resistance of 22kΩ with taps every 1k, allowing 0 to 2.2V to be read to the ADC of a microcontroller depending on the angle of the vane.

As clever as that is, [Ajoy] still had to pull off the coaxial part, which he did by drilling out the old motor shaft from one end to the other using just a drill press. The anemometer shaft passes through the hole in the shaft and turns a small DC motor to sense wind speed.

There might have been other ways to accomplish this, but given the constraints and the low cost of this solution, our hats are off to [Ajoy]. We’re a little concerned with that motor used for the anemometer, though. It could result in drag when used as a generator. Maybe a better solution would be a Hall-effect sensor to count rotations of a hard drive rotor.

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Take Your Samples For A Spin With The RWXBioFuge

October 21, 2014 by Theodora Fabio 14 Comments

We have a confession to make: we love centrifuges. We’ve used all shapes and sizes, for spinning bags of whole blood into separate components to extracting DNA, and everything in between. Unfortunately, these lab staples are too expensive for many DIY-biologists unless they buy them used or build them themselves. [Pieter van Boheemen] was inspired by other DIY centrifuges and decided to make his own, which he named the RWXBioFuge.

[Pieter] designed the RWXBioFuge using Sketchup, OpenSCAD, and InkScape. It features a Thermaltake SMART M850W ATX power supply, an R/C helicopter Electronic Speed Controller (ESC), and brushless outrunner motor. For user output it utilizes a 16×2 LCD character display with an I2C interface.The frame is laser-cut from 3mm MDF while the 3D-printed PLA rotor was designed with OpenSCAD.

An Arduino handles the processing side of things. [Pieter] used an Arduino Ethernet – allowing a web interface to control the centrifuge’s settings and operation from a distance. We can see this being useful in testing out the centrifuge for any rotor/motor balance issues, especially since [Pieter] states that it can be configured to run >10,000 rpm. We wouldn’t want to be in the room if pieces start flying off any centrifuge at that speed! However, we feel that when everything’s said and done, you should have a centrifuge you can trust by your side when you’re at your lab bench.

While there are similarities to the Openfuge, the larger RWXBioFuge has rotor capacities of eight to twenty 1.5-2.0ml microcentrifuge tubes. Due to the power supply, it is not portable and a bit more expensive, but not incredibly so. There are some small touches about this centrifuge that we really like. The open lid detector is always a welcome safety feature. The “Short” button is very handy for quick 5-10 second spins.

A current version of the RWXBioFuge is being used at the Waag Society’s Open Wetlab. [Pieter’s] planned upgrades for the next version include a magnetic lid lock, different rotor sizes, an accelerometer to detect an improperly balanced rotor, and optimizing the power supply, ESC, and motor setup. You can never have enough centrifuges in a lab, and we are looking forward to seeing this project’s progress!

Check out a few more pictures of the RWXBioFuge after the break.

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