Software Controlled Hard Drive Solenoid Engine

[Fabien-Chouteau] submitted his interesting solenoid engine. In an internal combustion, steam, or pneumatic piston engine, the motive force is produced by expanding gas. In [Fabien]’s little engine it is produced by the arm of a hard drive. Solenoid engines are usually just for show, and come in all shapes and sizes. If you want to move something using electricity an axial motor is probably a better bet. But if you want a challenge and a learning experience, this is hard to beat.

[Fabien] had some problems to solve before his motor made its first revolution. Just like a piston engine the timing needed to be exact. The arm firing at the wrong time could cause all sorts of trouble, the equivalent of backfire in a combustion engine. A STM32f4 discovery board was coupled with a Hall-effect sensor and a MOSFET. When the board read that the arm has moved back to the most efficient position for firing it sent a pulse through the coil. Just like a regular engine, getting the timing right makes all the difference. Once [Fabien] got it tuned up his motor could spin around at a steady 3000 rpm.

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Failaffle

Fail Of The Week: Not All Mold Releases Release All Molds.

I’m writing a series of articles on resin casting as an extension to my experiences with the instructions found in the wonderful Guerrilla Guide. However, mistakes were made. Having run out of my usual mold release I went to a back-up jar that was lying around from a casting project long, long ago in a workshop far, far away.

GLUE
Never much for readin’ the nutrition facts myself.

I’m refining a technique of making a mold the quick and dirty way. Everything was going well, the sprues looked good and the master released from the silicone. It was time to do the second half of the mold. As usual I applied a generous amount of mold release. Since it was the first time this mold was to be used I went ahead and did all the proper steps. Rubbing off the dried release and applying a few more coats just to be sure.

I was completely unaware that I was applying mold release designed for urethane molds only. In other words I thoroughly covered my silicone mold in silicone bonding agents. I remained unaware until trying to separate the halves of the mold and found them thoroughly joined. After going through the stages of grief I finally figured out where it all went wrong.

Oh well. I’m ordering some of my regular pick, Stoner A324, and that should do the trick. There’s also Mann- Ease Release 200. While having probably the best name a release agent can have, it doesn’t work as well and needs approximately 100 years to dry. After this setback I’d rather just, grudgingly, learn my lesson and order the correct thing.

I wonder if the smooth-on description can say URETHANE RUBBER a few more times.
Oh. Yes I see. Urethane… Urethane…

So now that we know the right way to fix this is to order the right product, is there a hack to get around it? Does anyone have a homebrew trick for release agent that can be used in a pinch? Leave your comments below.

A CNC Build Log From The Not So Distant Past

2007 wasn’t that long ago, but [Adam Ziegler’s] build log is, nevertheless, a pleasant romp through a not so distant past. From beginning to the end of the build, we enjoyed reading [Adam]’s progress and struggles as he worked through the build. Sometimes it’s hard to see the very normal daily work that goes into a project when it’s all polished up at the end.

He designed the mechanics himself, but after some less-successful attempts, decided to just buy the electronics. The machine is a well executed MDF gantry mill with conduit rails and 6000-series ball bearings on angle stock. It’s a good example of what you can do with cheap materials and careful planning.

[Adam] ran a few jobs on the machine, some of which he took on before it was even built (which he doesn’t recommend doing). After his adventure with this gateway machine, he’s put it up for sale and is purportedly working on a new model. The standard pattern of CNC addiction is a live alive and well.

If you’re looking to get into CNC machining on the cheap, we’ve seen similar affordable builds for your inspiration.

Tennis Ball Cannon

Tennis Ball Cannon With Clear Combustion Chamber

[hw97karbine] has made a pretty cool tennis ball cannon. While making a cannon of this sort is nothing new to us, we were impressed by the effort taken to get a stoichiometrically ideal mixture of 3.2% butane and air in the combustion chamber.

[hw97karbine] filled a syringe with butane and then dosed exact amounts into the chamber using a hole in the back. To control the air mixture he marked lines on the outside of the cylinder with magic marker. Simple but effective.

More rewarding than the methods was the cool slow-mo videography of the explosions in the chamber. You really have to check it out. [hw97karbine] shows clearly the difference between a well-balanced fuel to air mixture and a poorly balanced one. It’s one thing to say that more fuel does not mean better combustion, as we all remember from our personal potato cannon experiences, but it’s another thing entirely to see it.

[Via Reddit]

How do you even?

An Incredible Clock Made Of Popsicle Sticks

[alvenh] has come a long way since he was a kid, but he kept the bag of popsicle sticks from his childhood. When he set out to build a clock for himself, he remembered his stored treasure and made something unexpectedly good out of the humble material. We’ve seen some neat stuff made with popsicle sticks before, but they usually retain their familiar shape.

[alvenh] began by choosing a style for his clock. We don’t know how he looked at a bag of sticks and thought, “Old English Georgian bracket clock with a bell top,” but if Hackaday teaches anything, it’s that some people just have a wider vision for the world. Next he laminated the sticks together or used them as a veneer for a thinner sheet of plywood to make his base materials.

An incredible amount of work went into the clock as he did things like sanding large contours using a jar for a form, or cutting mortise and tenons into craft sticks. [alvenh] even painted the face of the clock using his German Shepard as a model. Finally he installed an antique movement into the creation. The final result is stunning, and the build log is fun to read through.

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Very Detailed BB-8 Robot Build

[James Bruton] has just finished and posted the designs for his very impressive BB-8 robot build. We covered the start of his adventures some time ago when we were theorizing about the secret in the new droid, but it was for a completely different robot design. [James] was pursuing a design that used a little robot sitting on top of a big ball.

This new version has a robot sitting inside a ball with the head being magnetically coupled to the body. Among many things with this build, we thought it was cool how the robot has one drive motor and turns by spinning up and reversing a big flywheel in the base of the robot. That was certainly not one of the top theories proposed for the secret behind the robot. The robot is mostly made with a 3d printer, with the occasional cosmetic piece being vacuum formed. If you’d like to make one for yourself, [James] has also posted all of the design and cad for the robot on his GitHub. On Thursday he posted the final installment of his 10-part video series on the build. Check out part one after the break.

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Raspberry Pi Zero – Programming Over USB

Raspberry Pi Zero – Turning The Pi Into A USB Gadget, Over USB

[gbaman] has figured out a simpler way to program the new Raspberry Pi Zero over USB without modifying the board. Why is this useful? One example which appealed to us was setting the Zero’s USB port up as a mass storage device. Imagine plugging in your Pi powered robot, dragging and dropping a Python script into the mass storage device that shows up, and pressing a button on the robot to run the new script. Pretty fancy for $5.00.

You can get the PI to emulate a whole range of devices from a USB MIDI controller to a simple USB serial interface. We’re excited to see what uses people come up with. Unfortunately the Pi Zero is still out of stock most everywhere as we wait for the next production run to finish. Though if you’ve got one, why not check out a few of our thoughts and experiences with the device!

[gbaman] based his work off the work done by [Dave-0] and others over at the Raspberry Pi forums. [LadyAda] also has a version of this hack, which we covered, that involves soldering a header to the pi and using a UART adapter.

[via Hacker News]