A Lesson In K40 Laser Repair

June 10, 2018 by Jenny List 25 Comments

The K40 laser cutter has become ubiquitous in hackerspaces and well-equipped home workshops over the past few years, as a relatively inexpensive introduction to laser cutting and a machine that is readily hackable. Tokyo Hackerspace have one, but sadly their laser tube failed after relatively little use. Replacing a laser tube might be a routine component change for some readers, but it’s still worth looking at in some detail.

Their tube had failed at its output lens cooling cap, a component that is glued onto the end of the tube rather than bonded, and which had snapped off. There had been no mechanical stress upon it, but it was found that the arrangement of their cooling system caused it to drain between uses and thus air bubbles could accumulate. The resulting cooling inefficiency caused enough thermal stress for the bond between the tube and the end piece to fail.

The in-depth analysis of what caused the failure and step-by-step description of the procedure should be of interest to any K40 owner. Little things such as ensuring that the tube is rotated to the right angle for all air bubbles to make their way out of it, or making sure that when the pump is switched off the water isn’t all pulled out of it by gravity seem obvious, but these are traps that will have caught more than one K40 owner.

We’ve covered many K40 stories over the years, but a good place to start for the novice might be this commissioning story, or even this tale of a hackerspace’s modifications to their model.

Robert Hall And The Solid-State Laser

May 22, 2018 by Dan Maloney 13 Comments

The debt we all owe must be paid someday, and for inventor Robert N. Hall, that debt came due in 2016 at the ripe age of 96. Robert Hall’s passing went all but unnoticed by everyone but his family and a few close colleagues at General Electric’s Schenectady, New York research lab, where Hall spent his remarkable career.

That someone who lives for 96% of a century would outlive most of the people he had ever known is not surprising, but what’s more surprising is that more notice of his life and legacy wasn’t taken. Without his efforts, so many of the tools of modern life that we take for granted would not have come to pass, or would have been delayed. His main contribution started with a simple but seemingly outrageous idea — making a solid-state laser. But he ended up making so many more contributions that it’s worth a look at what he accomplished over his long career.

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Gorgeous NickelBot Serves Up Lasered Wooden Nickels

May 9, 2018 by Donald Papp 22 Comments

[bdring] just recently completed his absolutely fantastic NickelBot, which is a beautifully made unit that engraves small wooden discs with a laser like some kind of on demand vending machine, and it’s wonderful. NickelBot is small, but a lot is going on inside. For example, there’s a custom-designed combination engraving platform and hopper that takes care of loading a wooden nickel from a stack, holding it firm while it gets engraved by a laser, then ejects it out a slot once it’s done.

NickelBot is portable and can crank out an engraved nickel within a couple of minutes, nicely fulfilling its role of being able to dish out the small items on demand at events while looking great at the same time. NickelBot’s guts are built around a PSoC5 development board, and LaserGRBL is used on the software side to generate G-code for the engraving itself. Watch it work in the video embedded below.

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Roll Up Your Sleeve, Watch A Video With This Smart Watch Forearm Projector

April 25, 2018 by Dan Maloney 35 Comments

We’re all slowly getting used to the idea of wearable technology, fabulous flops like the creepy Google Glass notwithstanding. But the big problem with tiny tech is in finding the real estate for user interfaces. Sure, we can make it tiny, but human fingers aren’t getting any smaller, and eyeballs can only resolve so much fine detail.

So how do we make wearables more usable? According to Carnegie-Mellon researcher [Chris Harrison], one way is to turn the wearer into the display and the input device (PDF link). More specifically, his LumiWatch projects a touch-responsive display onto the forearm of the wearer. The video below is pretty slick with some obvious CGI “artist’s rendition” displays up front. But even the somewhat limited displays shown later in the video are pretty impressive. The watch can claim up to 40-cm² of the user’s forearm for display, even at the shallow projection angle offered by a watch bezel only slightly above the arm — quite a feat given the irregular surface of the skin. It accomplishes this with a “pico-projector” consisting of red, blue, and green lasers and a pair of MEMS mirrors. The projector can adjust the linearity and brightness of the display to provide a consistent image across the uneven surface. An array of 10 time-of-flight sensors takes care of watching the display area for touch input gestures. It’s a fascinating project with a lot of potential, but we wonder how the variability of the human body might confound the display. Not to mention the need for short sleeves year round.

Need some basics on the micro-electrical mechanic systems (MEMS) behind the pico-projector in this watch? We’ve got a great primer on these microscopic machines.

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Bargain Bin Barcode Scanner Keeps Track Of Shopping Needs

April 23, 2018 by Dan Maloney 18 Comments

For most people, a Post-It note or dry-erase board suffices to ensure that household consumables are replenished when they’re used up. But hackers aren’t like most people, so this surplus barcode scanner turned kitchen inventory manager comes as little surprise. After all, if something is worth doing, it’s worth overdoing.

[Brian Carrigan]’s project began with a chance discovery of an old barcode scanner in his local scrap store. Questions as to why we can never find bargains like a $500 scanner for six bucks aside, [Brian] took the scanner home for a bit of reverse engineering. He knew it used RS-232 but it had been unceremoniously ripped from its connectors, so identifying pins took some detective work. With power and data worked out and the scanner talking to a Raspberry Pi, [Brian] set about integrating it into Wunderlist, a cloud-based list management app. Now when someone eats the last Twinkie, a quick scan of the package looks up the product name via an API call to the UPC database and posts it to Wunderlist. And we’ll bet the red laser beams bouncing around the kitchen make a great nightlight too.

With smartphone barcode reading apps, this might seem a bit like overkill, but we like it just the same. And if barcodes leave you baffled, check out our introduction to these studies in black and white that adorn just about everything.

Laser Projector Ditches Galvanometer For Spinning Drum

April 20, 2018 by Ben James 25 Comments

Laser projectors like those popular in clubs or laser shows often use mirror galvanometers to reflect the laser and draw in 2D. Without galvos, and on a tight budget, [Vitaliy Mosesov] decided that instead of downgrading the quality, he would seek an entirely different solution: a spinning mirror drum.

He fires a laser at a rotating drum with twelve mirror faces, each at a different adjustable vertical angle. The laser will hit a higher or lower point on the projection surface depending on which mirror it’s reflecting off – this creates resolution in the Y direction.

Timing the pulsing of the laser so that it reflects off the mirror at a certain horizontal angle provides the X resolution.

As you can already tell, speed and timing is critical for this to work. So much so that [Vitaliy] decided he wanted to overclock his Arduino – from 16 MHz to 24.576 MHz. Since this changes the baud rate, an AVR ISP II was used for programming after the modification, and the ‘duino’s hardware serial initialization had to be hacked too.

For the laser itself, [Vitaliy] designed some nifty driver circuitry, which can respond quickly to the required >50 kHz modulation, supply high current, and filter out voltage transients on the power supply (semiconductor lasers have no protection from current spikes).

On the motor side of things, closed loop control is essential. A photo-interrupter was added to the drum for exact speed detection, as well as a differentiator to clean up the signal. Oh, and did we mention the motor is from a floppy disk drive?

We’ve actually seen builds like this before, including a dot-matrix version with multiple lasers and one made apparently out of Meccano and hot-glue that can project a Jolly Wrencher. But this build, with its multiple, adjustable mirrors, is a beauty. Check it out in action below.

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3D-Printer Gets Hot-Swappable Hot-Ends

April 9, 2018 by Ben James 26 Comments

3D printers can be hacked into a multitude of useful machines, simply by replacing the filament extruder with a new attachment such as a laser engraver or plotter.

However, [geggo] was fed up with re-wiring and mounting the printhead/tool every time he wanted to try something new, and set out to design a modular printhead system for next-level convenience. The result? A magnetic base-plate, allowing a 3D printer to become a laser engraver within a matter of seconds. This new base-plate mounts onto the existing ball bearings and provides a sturdy place for attachments to snap to – with room for two at once.

Using neodymium magnets to mount the printhead to the base-plate provides enough force to keep the attachment in place and compress 30 pogo pins, which make the electrical connections. These carry the lines which are common to all attachments (heater, thermistor and fan), as well as custom connections for certain attachments – for example the extruder stepper motors. A Flexible Flat Cable (FFC) is used to connect the pogo pin PCB to the main controller.

So far, the list of tools available for fitting includes an MK8 extruder, a E3D v6 hotend (for Bowden extrusion), a laser, a micrometer dial indicator, and a pen plotter (used for writing a batch of wedding invitations!). There was even some success milling wood.

For some automated extruder switching action we’ve shown you in the past, check out the 3d-printer tool changer.

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