UV Light Box Cures Both Sides Of A PCB

November 11, 2017 by John Baichtal 6 Comments

[GiorgiQ] needed a UV light to cure the etch resist on his printed circuit boards, and what better way to accomplish this than to build the perfect UV light box himself? The box consists of a custom PCB (of course) featuring a pair of 12V relays tripping quad 9×12 matrices of 400nm UV LEDs, with a total of 432 diodes in use — not to mention resistors to protect the LEDs. All of it is run by an Arduino Nano.

The enclosure is made out of 12mm MDF and 3mm cast acrylic, and the circuit board fits into a tray sliding on drawer sliders, allowing a resist-covered board to be placed in a carrier and slid back in.

DIY light boxes mostly don’t look as slick as [GiorgiQ]’s, but they’re a fairly common project. This one also uses 9×12 matrices of UV LEDs, while a distinctly simpler project involves making a UV exposure box out of fluorescent lights.

A Sandbox For DIY Pinball Design

November 11, 2017 by Kristina Panos 21 Comments

If you’ve always wanted to build your own pinball machine but have no idea where to start, this is the project for you. [Chris] is in the process of building a 3/4 size pinball table and is currently in the waiting-for-parts stage. As they arrive, he is testing them in a sandbox he built in an afternoon. Let [Chris]’s proving ground be your quick-start guide to all the ways you could approach the two most important parts of any pin: the flippers and targets.

The field of play is a sturdy piece of particle board, and the cardboard walls are attached with hot glue. [Chris] designed and printed a pair of flippers that are driven by some cheap remote door lock motors he found at a popular online auction house. You can see how snappy are in the test video after the break.

We love the crisp action and elegant simplicity of the spring-loaded drop targets [Chris] designed. Right now he resets them manually, but soon they will be reset by a solenoid or maybe a motor. We can’t wait to see how the table turns out. In the meantime, we’ll have to go back to drooling over this amazing life-size 3D-printed pinball machine.

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Junkbox Freezer Alarm Keeps Steaks Safe

October 29, 2017 by Dan Maloney 24 Comments

A fully stocked freezer can be a blessing, but it’s also a disaster waiting to happen. Depending on your tastes, there could be hundreds of dollars worth of food in there, and the only thing between it and the landfill is an uninterrupted supply of electricity. Keep the freezer in an out-of-the-way spot and your food is at even greater risk.

Mitigating that risk is the job of this junkbox power failure alarm. [Derek]’s freezer is in the garage, where GFCI outlets are mandated by code. We’ve covered circuit protection before, including GFCIs, and while they can save a life, they can also trip accidentally and cost you your steaks. [Derek] whipped up a simple alarm based on current flow to the freezer. A home-brew current transformer made from a split ferrite core and some magnet wire is the sensor, and a couple of op-amps and a 555 timer make up the detection and alarm part. And it’s all junk bin stuff — get a load of that Mallory Sonalert from 1983!

Granted, loss of power on a branch circuit is probably one of the less likely failure modes for a freezer, but the principles are generally applicable and worth knowing. And hats off to [Derek] for eschewing the microcontroller and rolling this old school. Not that there’s anything wrong with IoT fridge and freezer alarms.

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Pop Goes The Haunted Jack-in-the-Box

October 21, 2017 by Kristina Panos 10 Comments

Is Halloween sneaking up on you, too? It’s less than two weeks away, but there is still plenty of time to build something that will scare the pants off trick-or-treaters and party guests alike. This year, Hackaday regular [Sean Hodgins] hacked his favorite holiday by taking something that ships with a base level of scariness and making it autonomous. What could be more frightening than a haunted toy?

The (decades-old) jack-in-the-box mechanism is simple. Turning the crank operates a mechanical music box that plays the traditional “Pop Goes the Weasel”. When the music box hits the high note, a jutting piece of plastic on the barrel of music box disturbs the other end of the latch, which frees the scary clown inside. [Sean] used a 100:1 DC motor to turn the crank from the inside, and a Pi camera to detect victims in the vicinity. Once the camera locks on to a face, the box cranks itself and eventually ejects the jester. Since most of the space inside is already taken up by the spring, [Sean] housed the electronics in a custom 3D-printed base with a hole cut out for the camera’s eye.

Many modifications are possible with a project like this. [Sean] is now in complete control of the latch operation, so he could make the clown pop appear instantly, or randomly, or sometimes not at all. Check out [Sean]’s entertaining build video after the break.

Want to make your own fright machine from scratch? We’ve got all the inspiration you need, from tabletop to trash can-sized monsters. Continue reading “Pop Goes The Haunted Jack-in-the-Box” →

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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Laser-Cut Modular Toolbox

September 28, 2017 by John Baichtal 15 Comments

[ystoelen] created this modular wooden toolbox out of laser-cut 5mm plywood secured with leather hinges bolted into place. The leather strips secure the various tool boards with grommets connecting to plastic plugs. The toolboards use cross-shaped holes with laser-cut plugs and strips of elastic securing the tools, allowing each board to be uniquely configured depending on what tool is being stored there. There is a larger, “main” board, onto which smaller boards can be placed depending on what tools you’ll need.

While this is a clever approach to tool transport, we have some concerns about this project. Usually the problem with a box full of tools is that you’ve overloaded it and can’t readily lift it up. Often this involves a steel toolbox that won’t break, no matter what happens. But a plywood construct isn’t nearly that strong, and if overloaded or dropped it’s gonna take some damage.

For more toolbox inspirations, read our posts on a machine shop in a toolbox as well as this Transformers-themed portable workbench.

Music Box Plays “Still Alive” Thanks To Automated Hole Puncher

September 19, 2017 by Donald Papp 20 Comments

Most projects have one or two significant aspects in which custom work or clever execution is showcased, but this Music Box Hole Punching Machine by [Josh Sheldon] and his roommate [Matt] is a delight on many levels. Not only was custom hardware made to automate punching holes in long spools of paper for feeding through a music box, but a software front end to process MIDI files means that in a way, this project is really a MIDI-to-hand-cranked-music-box converter. What a time to be alive.

The hole punch is an entirely custom-made assembly, and as [Josh] observes, making a reliable hole punch turns out to be extremely challenging. Plenty of trial and error was involved, and the project’s documentation as well as an overview video go into plenty of detail. Don’t miss the music box version of “Still Alive”, either. Both are embedded below.

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