Scratch-Building A Supersized Laser Cutter

November 20, 2018 by Tom Nardi 9 Comments

Now that 3D printers have more or less hit the mass market, hackers need a new “elite” tool to spend their time designing and fiddling with. Judging by the last couple of years, it looks like laser cutters will be taking over as the hacker tool du jour; as we’re starting to see more and more custom builds and modifications of entry-level commercial models. Usually these are limited to relatively small and low powered diode lasers, but as the following project shows, that’s not always the case.

This large format laser cutter designed and built by [Rob Chesney] is meticulously detailed on his blog, as well as in the in the video after the break. It’s made up of aluminium profile and a splattering of ABS 3D printed parts, and lives in an acrylic enclosure that’s uniquely isolated from the laser’s internal gantry. All told it cost about $2,000 USD to build, but considering the volume and features of this cutter that’s still a very fair price.

[Rob] carefully planned every aspect of this build, modeling the entire machine in CAD before actually purchasing any hardware. Interestingly enough his primary design constraint was the door to his shed: he wanted to build the largest possible laser cutter that could still be carried through it. That led to the final machine’s long and relatively shallow final dimensions. The design was also guided by a desire to minimize material waste, so when possible parts were designed to maximize how many could be cut from a one meter length of aluminum extrusion.

The laser features a movable Z axis that’s similar in design to what you might see in a Prusa-style 3D printer, with each corner of the gantry getting an 8 mm lead screw and smooth rod which are used in conjunction to lift and guide. All of the lead screws are connected to each other via pulleys and standard GT2 belt, but as of this version, [Rob] notes the Z axis must be manually operated. In the future he’ll be able to add in a stepper motor and automate it easily, but it wasn’t critical to get the machine running.

He used 3D printed parts for objects which had a relatively complex geometry, such as the laser tube holders and Z axis components, but more simplistic brackets were made out of cut acrylic. In some components, [Rob] used welding cement to bond two pieces of acrylic and thereby double the thickness. Large acrylic panels were also used for the laser’s outer enclosure, which was intentionally designed as a separate entity from the laser itself. He reasoned that this would make assembly easier and faster, as the enclosure would not have to be held to the same dimensional tolerances as it would have been if it was integrated into the machine.

[Rob] gives plenty of detail about all the finer points of water cooling, laser control electronics, aligning the mirrors, and really anything else you could possibly want to know about building your own serious laser cutter. If you’ve been considering building your own laser and have anything you’re curious or unsure about, there’s a good chance he addresses it in this build.

Short of having the fantastically good luck to find a laser cutter in the trash that you can refurbish, building your own machine may still be the best upgrade path if you outgrow your eBay K40.

Continue reading “Scratch-Building A Supersized Laser Cutter” →

High Voltage Measurement Is Shockingly Safe

November 17, 2018 by Bryan Cockfield 9 Comments

With the right equipment and training, it’s possible to safely work on energized power lines in the 500 kV range with bare hands. Most of us, though, don’t have the right equipment or training, and should take great care when working with any appreciable amount of voltage. If you want to safely measure even the voltages of the wiring in your house there’s still substantial danger, and you’ll want to take some precautions like using isolated amplifiers.

While there are other safe methods for measuring line voltage or protecting your oscilloscope, [Jason]’s isolated amplifier method uses high voltage capacitors to achieve isolation. The input is then digitized, sent across the capacitors, and then converted back to an analog signal on the other side. This project makes use of a chip from TI to provide the isolation, and [Jason] was able to build it on a perfboard while making many design considerations to ensure it’s as safe as possible, like encasing high voltage sections in epoxy and properly fusing the circuit.

[Jason] also discusses the limitations of this method of isolation on his site, and goes into a lot of technical details about the circuit as well. It probably wouldn’t get a UL certification, but the circuit performs well and even caught a local voltage sag while he was measuring the local power grid. If this method doesn’t meet all of your isolation needs, though, there are a lot of other ways to go about solving the problem.

Arduino Provides Hands-Free Focus For Digital Inspection Scope

November 12, 2018 by Dan Maloney 6 Comments

With surface-mount technology pushing the size of components ever smaller, even the most eagle-eyed among us needs some kind of optical assistance to do PCB work. Lots of microscopes have digital cameras too, which can be a big help – unless the camera fights you.

Faced with a camera whose idea of autofocus targets on didn’t quite coincide with his, [Scott M. Baker] took matters into his own hands – foot, actually – by replacing mouse inputs to the camera with an outboard controller. His particular camera’s autofocus can be turned off, but only via mouse clicks on the camera’s GUI. That’s disruptive while soldering, so [Scott] used an Arduino Pro Micro and a small keypad to mimic the mouse movements needed to control the camera.

At the press of a key, the Arduino forces the mouse cursor up to the top left corner of the screen, pulls down the camera menu, and steps down the proper distance to toggle autofocus. The controller can also run the manual focus in and out or to take a screenshot. There’s even a footswitch that forces the camera to refocus if the field of view changes. It looks really handy, and as usual [Scott] provides a great walkthrough in the video below.

Like it or not, if shrinking technology doesn’t force you into the microscope market, entropy will. If you’re looking for a buyer’s guide to microscopes, you could do worse than [Shahriar]’s roundup of digital USB scopes. Or perhaps you’d prefer to dumpster dive for yours.

Continue reading “Arduino Provides Hands-Free Focus For Digital Inspection Scope” →

The How And Why Of Laser Cutter Aiming

November 9, 2018 by Tom Nardi 16 Comments

Laser aficionado [Martin Raynsford] has built up experience with various laser cutters over the years and felt he should write up a blog post detailing his first-hand findings with an often overlooked aspect of the machines: aiming them. Cheap diode laser cutters and engravers operate in the visible part of the spectrum, but when you get into more powerful carbon dioxide lasers such as the one used in the popular K40 machines, the infrared beam is invisible to the naked eye. A secondary low-power laser helps to visualize the main laser’s alignment without actually cutting the target. There are a couple of ways to install an aiming system like this, but which way works better?

[Martin] explains that there are basically two schools of thought: a head-mounted laser, or a beam combiner. In both cases, a small red diode laser (the kind used in laser pointers) is used to indicate where the primary laser will hit. This allows the user to see exactly what the laser cutter will do when activated, critically important if you’re doing something like engraving a device and only have one chance to get it right. Running a “simulation” with the red laser removes any doubt before firing up the primary laser.

That’s the idea, anyway. In his experience, both methods have their issues. Head-mounted lasers are easier to install and maintain, but their accuracy changes with movement of the machine’s Z-axis: as the head goes up and down, the red laser dot moves horizontally and quickly comes out of alignment. Using the beam combiner method should, in theory, be more accurate, but [Martin] notes he’s had quite a bit of trouble getting both the red and IR lasers to follow the same course through the machine’s mirrors. Not only is it tricky to adjust, but it’s also much more complex to implement and may even rob the laser of power due to the additional optics involved.

In the end, [Martin] doesn’t think there is really a clear winner. Neither method gives 100% accurate results, and both are finicky, though in different scenarios. He suggests you just use whatever method your laser cutter comes with from the factory, as trying to change it probably isn’t worth the effort. But if your machine doesn’t have anything currently, the head-mounted laser is certainly the easier one to retrofit.

In the past, we’ve covered a third and slightly unconventional way of aiming the K40, as well as a general primer for anyone looking to pick up eBay’s favorite laser cutter.

Tractor Drives Itself, Thanks To ESP32 And Open Source

November 9, 2018 by Donald Papp 31 Comments

[Coffeetrac]’s ESP32-based Autosteer controller board, complete with ~~OLD~~ OLED display for debugging and easy status reference.

Modern agricultural equipment has come a long way, embracing all kinds of smart features and electronic controls. While some manufacturers would prefer to be the sole gatekeepers of the access to these advanced features, that hasn’t stopped curious and enterprising folks from working on DIY solutions. One such example is this self-steering tractor demo by [Coffeetrac], which demonstrates having a computer plot and guide a tractor through an optimal coverage pattern.

A few different pieces needed to come together to make this all work. At the heart of it all is [Coffeetrac]’s ESP32-based Autosteer controller, which is the hardware that interfaces to the tractor and allows for steering and reading sensors electronically. AgOpenGPS is the software that reads GPS data, interfaces to the Autosteer controller, and tells equipment what to do; it can be thought of as a mission planner.

[Coffeetrac] put it all together with everything controlled by a tablet mounted in the tractor’s cab. The video is embedded below, complete with a “cockpit view” via webcam right alongside the plotted course and sensor data.

Continue reading “Tractor Drives Itself, Thanks To ESP32 And Open Source” →

Printed Parts Turn Ruler Into Marking Gauge

November 7, 2018 by Tom Nardi 19 Comments

For Hackaday readers who spend more time with a soldering iron than a saw, a marking gauge is a tool used to put parallel lines on a piece of wood (and occasionally metal or plastic) for cutting. The tool is run across the edge of the piece to be marked, and an adjustment allows the user to set how far in the line will be made. As an example, if you wanted to cut a board into smaller strips, a marking gauge would be an ideal choice for laying out your lines ahead of time.

But as with many niche tools, it’s not something you’re going to use every day. For [chaosbc], this meant he wanted to see if he could come up with a DIY solution on the cheap. Plus he could have it in hand now, rather than waiting for it to take the slow boat from overseas. With the addition of a few clever 3D printed components, he was able to turn his trusty aluminum ruler into a serviceable marking gauge for the cost of filament and a few bits of hardware.

The general design of a marking gauge is fairly simple: there’s a block that rides up and down a graduated shaft (known as the headstock) which allows you to set the depth of the line, and then a piece on the end which holds your marking tool. The marking tool could be a blade if you’re working with something soft enough, but for wood is usually going to be a pencil.

[chaosbc] provides all the STL files for his DIY marking gauge, though they might need adapting as they were created for his specific ruler. Luckily the parts aren’t that complex so it shouldn’t be too difficult to get it sorted out. He also has a useful hint for anyone looking to duplicate his work: a few drops of super glue on the bolt used to lock down the headstock is enough to create a non-marring surface so you don’t tear up your ruler.

We’ve got a few other tips for woodworking on a budget, as well as a primer about this whole making stuff with dead trees concept.

Continue reading “Printed Parts Turn Ruler Into Marking Gauge” →

Junkbox Constant Current Source Helps With Kelvin Sensing

November 7, 2018 by Dan Maloney 3 Comments

Is it ironic when a YouTube channel named “The Current Source” needs to build a current source? Or is that not ironic and actually just coincidental?

Regardless of linguistic considerations, [Derek], proprietor of the aforementioned channel has made and disassembled a few current sources in his day. Most of those jobs were for one-off precision measurements or even to drive a string of LEDs in what he describes as a pair of migraine-inducing glasses. Thankfully, The junk box current source presented in the video below is more in service of the former than the latter, as his goal is to measure very small resistances in semiconductors using Kelvin clips.

The current source uses a 24-volt switch-mode power supply and the popular LM317 adjustable voltage regulator. The ‘317 can be configured in a constant current mode by connecting the chip’s adjustment pin to the output through a series resistance. A multiturn pot provides current adjustment, although the logarithmic taper is not exactly optimal for the application. We spotted a pair of what appear to be optoisolators in the build too, but there’s no schematic and no discussion of what they do. [Derek] puts the final product to use for a Kelvin measurement of a 0.47-Ω 1% resistor at the end of the video.

We’re glad to see [Derek] in action; you may recall his earlier video about measuring his own radiation with a Geiger counter after treatment for thyroid cancer. Here’s hoping that’s behind him now.

Continue reading “Junkbox Constant Current Source Helps With Kelvin Sensing” →