Low-Power Motor Can Run For Years On A Coin Cell

December 25, 2017 by Dan Maloney 29 Comments

Can you run an electric motor for two years on a single lithium coin cell? [IamWe] figured out how to do it, and even though his donut motor doesn’t look like any motor we’ve ever seen before, it’s a pretty solid lesson in low-current design.

The donut motor is really just a brushless DC motor with a sign-pole stator and a multi-pole rotor. The frame of the motor is built from a styrofoam donut, hence the motor’s name. The rotor is a styrofoam sphere with neodymium magnets embedded around its equator. A sharpened bicycle spoke serves as an axle, and clever magnetic bearings provide near-zero friction rotation. The stator coil comes from an old solenoid and is driven by a very simple two-transistor oscillator. [IamWe]’s calculations show that the single CR2032 coin cell should power this motor for over two years. This one looks easy enough to whip up that it might make a nice project for a long winter’s night. Watch it spin in the video below.

This one seems like a perfect entry for the Coin Cell Challenge contest. Sure, it may not be a coin cell jump starter for your car, but our guess is this motor will still be spinning in 2020, and that’s no mean feat.

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Over-Engineered Mailbox Flag Machined Using Under-Engineered Mini-Lathe

October 3, 2017 by Anool Mahidharia 55 Comments

[Tim Nummy] used his cheap, Chinese, bench mini-lathe to make a non-terrible mailbox flag holder (YouTube video, embedded below). Tim posts videos on his channel about garage hobby projects, many of which are built using his mini-lathe, often based on suggestions from his followers. One such suggestion was to do something about his terrible mailbox flag – we’re guessing he receives a lot of old-school fan mail.

He starts off by planning the build around 1 ¼ inch aluminum bar stock, a 688 bearing, three neodymium magnets and some screws. The rest of it is a “think and plan as you go along” project, but essentially, the new holder is in three pieces. An inner piece goes inside the mail box and holds the assembly to the mail box. The middle piece holds the two magnets which act as end-stops or limits for the flags raised and lowered positions. The final, outer piece holds the flag itself, and the bearing which allows it to rotate freely.

This part also has the third magnet embedded in it to work with the other two magnets for the limits. The use of magnets is cool, but a ball catch with two detents would have worked just as well. It’s a great simple project to follow for those who want to wet their feet on lathe work. [Tim] has also posted links to all of the tools and equipment seen in the video, so check that out if anything catches your fancy.

But workshop veterans will almost certainly cringe at several places along the video. The main one that caught our eye is obviously the shaky lathe itself. It could do with a heavier workbench, proper leveling, foundation bolts or anti-vibration mounts. And from the looks of it, the tail stock isn’t any rock steady too. Although the lathe is variable speed, the chuck rpm is set too high for aluminum, and the lack of cutting fluid makes it even more troublesome. Using oil, or even some cutting fluid, while tapping would have been wise too.

We’re not sure if it’s the shaky foundation or poor feed control, but the step cut for mounting the bearing is over-sized by a whole lot more and requires a big goop of retaining compound to glue the bearing in place. But the end result works quite well, including the magnetic catches – a complex solution for a simple problem.

We’re sure our keen-eyed readers will likely spot some more issues in [Tim]’s methods, so go at it in the comments below, but please make sure to rein in the snark and keep your feedback positive.

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Powerful, Professional Brushless Motor From 3D-Printed Parts

May 8, 2017 by Dan Maloney 23 Comments

Not satisfied with the specs of off-the-shelf brushless DC motors? Looking to up the difficulty level on your next quadcopter build? Or perhaps you just define “DIY” as rigorously as possible? If any of those are true, you might want to check out this hand-wound, 3D-printed brushless DC motor.

There might be another reason behind [Christoph Laimer]’s build — moar power! The BLDC he created looks more like a ceiling fan motor than something you’d see on a quad, and clocks in at a respectable 600 watts and 80% efficiency. The motor uses 3D-printed parts for the rotor, stator, and stator mount. The rotor is printed from PETG, while the stator uses magnetic PLA to increase the flux and handle the heat better. Neodymium magnets are slipped into slots in the rotor in a Halbach arrangement to increase the magnetic field inside the rotor. Balancing the weights and strengths of the magnets and winding the stator seem like tedious jobs, but [Cristoph] provides detailed instructions that should see you through these processes. The videos below shows an impressive test of the motor. Even limited to 8,000 rpm from its theoretical 15k max, it’s a bit scary.

Looking for a more educational that practical BLDC build? Try one cobbled from PVC pipes, or even this see-through scrap-bin BLDC.

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Pimp My Cutting Fluid Pot

June 26, 2014 by Kristina Panos 16 Comments

oil pot

Think about the simple tools you use every day. From writing implements to wire spoolers, there is arguably nothing that deserves to be hot rodded more than the things you depend on and might even take for granted.

For mad machinist [Chris], one of those everyday tools is his cutting fluid pot. Of course he already had one. A heavy one. A manly one. But it wasn’t completely ideal, and it wasn’t plated with gold that he prospected, refined, and processed himself. More on that in a minute.

[Chris] had obtained some neodymium ring magnets a while back. He was playing around with them in his shop when he noticed that his cutting fluid applicator brush fit nicely through the center and, being metal, was contained nicely through the wonders of magnetism. It was then that he decided to build a cutting fluid pot that would keep his brush in place and remain upright. Better living through magnetism.

He drilled and chamfered the brush hole out of a #20 JIC hydraulic cap and used the matching plug for the base. In case your catalog is out of reach, those are a 1¼” pair. [Chris] bored tiny pockets in the base for tiny magnets. After bathing both parts in delicious brake cleaner, he adhered all the magnets with LOCTITE®.

Okay, so, he’s done, right? No. Of course not. It did not surprise us to learn that [Chris] is also a miner, and not the 8-bit kind that hates creepers. Over the last two years, he prospected, refined, and other gold-related verbs using equipment he made himself. Just make the jump and watch the video before we give it all away. You’ll laugh, you’ll cry, you’ll be compelled to watch his other videos.

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Build A Levitating Bed For Under $1000

May 23, 2012 by Caleb Kraft 98 Comments

Many of us have had this exact thought and wondered if it was feasible. As it turns out, you can, in fact, just buy a bunch of magnets and make a levitating bed. Those magnets need to be extremely strong, so [mememetatata] used some rather large Neodymium magnets. This frame involved some careful planning since these magnets can actually be quite dangerous if not handled properly. [mememetatata] did manage to get everything spaced correctly and now has a bed that can levitate holding up to about 250 lbs. We really want to know what it feels like. That kind of thing seems as though it would be difficult to describe.

As usual, more information might be available in the reddit thread.

[thanks poisomike87]!

Engineering With Magnetic Spheres

January 14, 2010 by Mike Szczys 32 Comments

We would imagine these experiments were spawned by a devastatingly boring day at the office. [Sparr] found himself the proud owner of one thousand rare-earth magnets and decided to see what geometric shapes he could build with the spheres. These are gold-plated N35 Neodymium magnets that measure just 6mm across. He discovered that every structure is built from rings of magnets with shapes dependent upon what sequence of increasing or decreasing members are used. What he’s done is visually pleasing but we’d like to try it ourselves to see how resilient each structure ends up being.

[Sparr’s] post is from the Freeside Atlanta blog, a hacker space collective. [Curbob], a regular with the group, tipped us off that a few hacker conventions are coming up in their area and they’re looking for speakers for one-hour talks about projects. If you’re near Raleigh or Atlanta this is your chance to show off that ridiculously complicated project you’ve been risking your marriage to complete.