Fail Of The Week: Smoking Pulse Sensor And BLE Disappointment

September 19, 2013 by Mike Szczys 12 Comments

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We think [Thomas Brittain] is onto something. We often post to our personal blogs so that we have a reference to how we did something. But he also keeps a long post that documents his abandoned projects. It ends up serving as a quick start if he ever decides to pick up the torch once again. Lucky for us he’s included his failures in the write up. This Fail of the Week features the top two posts on his Incomplete Works page. The first is an attempt to make his own pulse sensor. The second is a miserable experience with a cheap Bluetooth Low Energy module.

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Fail Of The Week: Laser Cutter That Makes Jagged Edges

September 12, 2013 by Mike Szczys 45 Comments

This Fail of the Week is really only a failure because of the standards to which [eLabz] holds himself. The rig pictured above is a laser cutter built out of DVD drive parts. It goes above and beyond most of the optical drive CNC projects we see around here — it actually makes cuts! But [eLabz] looks on it as a failure because the steps of the driver motors are visible as jagged edges in those cuts. We see this more as a pausing point in the development process before the next refinement is made.

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Fail Of The Week: GPS Module Design

September 5, 2013 by Mike Szczys 68 Comments

GPS is really fun to play with in your projects. But when [Trax] decided to build a GPS chip into his design the fun ended abruptly. Above you can see the section of the board devoted to the hardware. Unfortunately this PCB fails to provide any GPS location data whatsoever.

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Fail Of The Week: Motorizing A PCB Cutting Shear

August 29, 2013 by Mike Szczys 43 Comments

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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Fail Of The Week: Switched-mode PSU Camera Battery Replacement

August 22, 2013 by Mike Szczys 52 Comments

We really wanted this week’s Fail to work. [Michael] wanted more juice for his Nikon D3100 camera. The idea he had was to replace the cells of the battery with a Buck converter and add leads for an external battery. This opens up the possibility of running from a wide range of voltage sources; an attractive prospect for devices using specialize batteries. Specifically, he wanted to swap out the stock 7.4V 1030 mAh battery and use an 18 Ah lead acid one instead.

The biggest hurdle to get over in a project like this one is the logic the camera uses to communicate with the battery. For this reason — and for the ease of hitting the right form factor — he scrapped an old battery pack to reuse the logic board and enclosure. His power supply is a free-formed circuit which fits nicely in the allotted space.

The circuit powers up, but only to about 6.4V. This isn’t enough to run the camera, which means this was just an expensive way for [Michael] to practice his soldering. After the jump you can read his recounting of the experience. You’ll also find a few of the build images, and the two hand-drawn schematics he used during development. His Dropbox has the entire collection of images.

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Fail Of The Week: The Follies Of A Bootstrapped CNC Mill

August 15, 2013 by Mike Szczys 34 Comments

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Anyone who’s built their own CNC machine from scratch will tell you that it’s no walk in the park. Heck, even commercially available (but hobby priced) 3D printers are no picnic to get running reliably. This offering is the tale of how [Brian Amos] failed at building a CNC mill over and over again. But hey, that ‘over and over again’ part is what makes great hackers. He not only documented what didn’t work, but shows the hacks that he tried using to work through each scrape.

We think the most interesting bits are in his second post, but start with the first one (it’s a quick read) to get the background on the project. The real issues start with a common one: a bed that is severely unlevel compared to the cutting head’s axes. The solution is to use a sacrificial bed, milling it out to match the surface to the tool. This exposed the next issue which is a misaligned Z axis. Some give in the entire support structure means problems with slop and backlash. And there’s even a very creative spiral-cut coupler to help account for alignment issues between the lead screws and motors.

The nice thing about building a mill is that you can turn around a use it to mill more accurate replacement parts. Just keep telling yourself that as you toil away at a project that just won’t seem to work!

We’re already looking for next week’s fail post topic. Help keep the fun rolling by writing about your past failures and sending us a link to the story.

Fail Of The Week: Inaugural Edition

August 8, 2013 by Mike Szczys 115 Comments

We’re sure you’ve all been waiting on the edge of your seats to see whose project makes it as the first Hackaday Fail of the Week. Wait no longer, it’s [Mobile Will] with his woeful tale about monitoring AC current usage.

He had been working on a microcontroller actuated mains outlet project and wanted an accurate way to measure the AC current being used by the device connected to it. The ADE7753 energy metering IC was perfect for this so he designed the board above and ordered it up from OSH Park. After populating the components he hooked it up to his Arduino for a test run, and poof! Magic blue smoke arose from the board. As you’ve probably guessed — this also fried the Arduino, actually melting the plastic housing of the jumper wire that carried the rampant current. Thanks to the designers of the USB portion of his motherboard he didn’t lose the computer to as the current protection kicked in, requiring a reboot to reset it.

We can’t wait to hear the conversation in the comments. But as this is our first FotW post we’d like to remind you: [Mobile Will] already knows he screwed up, so no ripping on his skills or other non-productive dibble. Let’s keep this conversation productive, like what caused this? He still isn’t completely sure and that would be useful information for designing future iterations. Update: here’s the schematic and board artwork.

We’ve got a bit more to share in this post so keep reading after the break.

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