Scrappy Lil’ Circular Saw

Like a lot of us, [Andrea] has a habit  of disassembling everything he runs into. He recently came across a fairly substantial motor he’d salvaged and envisioned its new life as a small circular saw.

[Andrea] bought new cutting discs, but the rest is salvage and scrap. He had already mounted the motor, pivot, belt, and gear to a wood block, so he added two more wood scraps for a base and a cutting surface. He screwed a metal L beam to one side of the surface block to keep the disc adjacent to the edge. A couple of washers keep the disc rotating freely. [Andrea] used a piece of hydraulic pipe and a cylindrical nut to attach the disc to the pivot. This assembly can be easily tightened by hand, so changing discs is a quick operation.

He kept the electrical as-is and mounted the box to the saw body. This 30W motor runs at ~600-1000RPM which isn’t fast enough to cut wood. Undeterred, [Andrea] plans to use it to cut steel bolts, copper circuit boards, and metal plates. If you need to cut through anything and everything, try this 700W DIY table saw.

Producing Ozone at 3500 RPM


Motors are fun, and high voltage even more so. We’re guessing that’s what went through [brazilero2008]’s mind when he put together an electrostatic motor using upcycled parts he found lying around.

The electrostatic rotor works by connecting a very high voltage, low current power supply – in this case an industrial air ionizer – to a set or rotors surrounding a plastic rotor. The hot electrodes spray electrons onto the rotor, which are picked up by the ground electrodes. If the system doesn’t arc too much, you have yourself a plastic rotor that spins very, very fast.

[brazilero]’s device is made out of an aluminum turkey pan, a few acrylic tubes, and a few cardboard disks; all stuff you can find in a well-stocked trash can. After completing the device, it was taken apart and finished and screwed onto a beautiful painted jewelry box. Very cool for something you can make out of trash, and dangerous enough to be very interesting.

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Talkbot: an Arduino-driven robot for beginners


It isn’t exactly WALL-E, but [Bithead’s] affordable introduction to robots — Talkbot — is made out of a trash can. This little guy runs off an Arduino and comes packed with features, including a voice chip, a motor shield, and a pair of bump sensors. Talkbot will cruise around until a bump sensor slams into an obstacle. One of his prerecorded messages will then play through the speaker while he backs up, turns, and tries to find a clearer path.

According to [Bithead’s] build log, tracking down the right bargain voice chip was a bit of a hassle; he skipped over the text-to-speech options only to be stalled by vendor issues. He finally settled on a clone of Sparkfun’s WTV020SD chip sourced from eBay, which allows you to access pre-recorded WAV files stored on a Micro-SD card. The robot’s body comes straight off the hardware store shelf, with PVC pipe for arms and a polystyrene base to hold all the parts.  At the bargain price of $110, [Bithead’s] students will have a true hacker experience cobbling the Talkbot together rather than using a prefab kit.

Be sure to see Talkbot  in a video below, performing either his green-eyed “friendly mode” or red-eyed “grumpy mode,” which dictates how pleasantly he responds to obstacles. Need something more advanced? Check out the tentacle robot, just in time for Halloween.

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Fail of the Week: Motorizing a PCB cutting shear

This week’s fail is an attempt to retrofit a PCB cutting shear with a geared motor. The project was undertaken by [David Cook]. Incidentally he’s very near and dear to us as his book Robot Building for Beginners got us started with hacking in the first place.

This $200 shearing tool is hand-operated and can cut through boards up to 1/16″ thick. But [David] really had to crank on the thing to make a cut. This often resulted in crooked board edges. He decided to do the retrofit in order to achieve higher precision. He sourced a high-torque motor from eBay for around $50 delivered.

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1,200 hours of work results in the smallest v12 engine

[José Manuel Hermo Barreiro] has spent many many hours crafting these tiny engines from hand. Every single piece is custom made specifically for the engine it is going onto. He has created aircraft engines, car engines, and marine engines that all actually run and are the smallest of their kind in the world.

At one point in this video he stands in a room with several engines lined up, all running smoothly and considers that there are possibly over 15,000 hours of work right there in front of him.

Here’s a video specifically about the 12 cylinder construction.

[Thanks Staskazz]


Altering automotive window motors for use in your projects


We agree with [Mário Saleiro] that the motors from a car’s power windows make for a fantastic high-torque solution to your next project. If you have a you-pick junkyard in your town they’ll be dirt cheap after you put in a bit of time to find and removing the parts from the yard. But you’ll probably want to add a few extra steps to get them ready, and he’s done a great job of documenting how he augmented them with wheels and rotary encoders.

One aspect of the project which really struck home with us was his machine-shop-101 style tricks to mate the axle of the motor with the wheel. He has a process which ensures you will find the exact center of a cylinder as you work. This starts by lining up a bench vice on his drill press. He then inserts a drill bit upside down in the drill chuck, lowers it and clamps the vice on the bit. After loosening the chuck he ends up with the bit pointing up at the exact center of the chuck. Next he chucks up a piece of threaded rod, drilling a perfectly centered hole by lowering it into the drill bit while the drill press is rotating. The image above shows him using this machined part as a guide to continue the hole into the motor’s axle. Click through the link above to learn the rest of the tricks he uses.

Working 3D printed stepper motor

Stepper Small 1

Most 3D printers use stepper motors to control the movement of the extruder head. If you could actually print those motors it would be one more big step toward self-replicating hardware. Now obviously [Chris Hawkins’] working 3d printed stepper motor wasn’t built 100% through 3D printing, but the majority of the parts were. All that he had to add was the electronic driver pieces, magnets, wire, and a few nails.

The coils are made up of nails wrapped in magnet wire. The rotor is a 3D printed framework which accepts neodymium rare earth magnets. The axle is pointed which reduces the friction where it meets the cone-shaped support on either side of the frame. The IC on the upper right is a transistor array that facilitates switching the 20V driving the coils. The board on the lower right is a Digispark, which is an ATtiny85 breakout board that includes a USB edge connector for programming and a linear regulator which is how he gets away with feeding 20V as the source.

Don’t miss the demo video after the break where you can see the motor stepping 7.5 degrees at a time.

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