Minimalist Robot Arm Really Stacks Up

August 19, 2021 by Dan Maloney 7 Comments

There’s nothing like a little weekend project, especially one that ends up better than you expected. And when you literally build a robotic arm out of workshop scraps, so much the better.

Longtime readers will no doubt recognize the build style used here as that of [Norbert Heinz], aka “Homofaciens” on YouTube. [Norbert] has a way of making trash do his bidding, and has shown us all kinds of seemingly impossible feats of mechatronics with just what’s lying around. In this case, his robot arm is made from scrap wooden roofing battens, or what we’d call furring strips here in the US. The softwood isn’t something you’d think would make a great material for building robots, but [Norbert] makes its characteristics work for him, like using wax-lubricated holes for hinge points. Steppers and lead screws cannibalized from an old CNC build, along with the drive electronics, provide the motion. It’s a bit — compliant — but precise enough to pick up nuts and stack them nicely. The video below gives an overview of the build, and detailed instructions are available too.

We always appreciated [Norbert]’s minimalist builds, and seeing what can be accomplished with almost nothing is always inspirational. If you’re not familiar with his work, check out his cardboard and paperclip CNC plotter, his tin can encoders, or his plasma-powered printer.

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Giant CNC Machine Measures A Full Cubic Meter

August 8, 2021 by Lewin Day 32 Comments

There are plenty of designs for table-top 3D printers, engravers, and general CNC machines out there. However, if you wanna build big things and build them fast, sometimes you need a machine that can handle bigger jobs. This gigantic 1x1x1 m 5-axis CNC machine from [Brian Brocken] absolutely fits the bill.

The build relies on 3D-printed components and aluminium tubing to make it accessible for anyone to put together. [Brian] notes that 25×25 mm tubing with a 2 mm wall thickness does an okay job, but those aiming to minimize deflection would do well to upgrade to 5 mm thickness instead. Stepper motors are NEMA 23 size, though the Y-axis uses a pair of NEMA 17s. This is necessary to deal with the immense size of the machine. Control is thanks to an Arduino Mega fitted with a RAMPS board, running the Marlin firmware.

The plan is to use the machine to test out a variety of CNC machining techniques. It could make for a great maxi-sized 3D printer, and should be able to handle some basic 5-axis milling of very soft materials like foams. This might seem silly on the face of it, but it can be of great use for mold making tasks.

We’ve seen giant CNC routers built before, too, and they can readily be put to great use. Video after the break.

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Custom Caliper Tracks For When You’re Going The Distance

August 5, 2021 by Sonya Vasquez 15 Comments

The working principle of digital calipers is mysterious enough that we’d never think to dismantle, much less improve them, right? Well, think again, as [Limi DIY] retrofits the processing element onto a custom track, extending the calipers measurement distance to a whopping 650 mm. Combined with a prior project to extract the measurement data, the result makes for a working multi-axis digital readout, a handy device for machine tools like a manual lathe or milling machine.

Digital calipers operate on the principle of measuring an array of variable capacitors. If we scratch our heads and look back at our physics notes, we’ll recall that the capacitance between two parallel conductive plates is linearly proportional to the surface area. By fixing one dimension of both plates and by sliding one plate over the other, we effectively change the area, giving ourselves a simple linear displacement sensor! (There are some classy error-correcting techniques too, and this [PDF] is a great place to look for more details.)

The theory takeaway is that this array of parallel plates can be embedded directly into a printed circuit board. We just need to know the dimensions. After some close measurement work, [Limi DIY] extracted the crucial measurements and fabbed a PCB with the pattern duplicated over 650 mm. After retrofitting the original processing element onto this new track, they had a working measurement device that’s far longer than the original!

If you’ve ever been tempted to disassemble your calipers but too nervous to bite off the investment, now’s your chance to follow along as [Lima DIY] demonstrates the gratuitous disassembly process for you in video format. And the fruits of their labor is also captured on a project post that includes the key dimensions if you’re looking to do the same thing.

If you’re looking for other ways to improve your calipers, why not start by giving them a major battery life boost.

Thanks to [absd] via [Jubilee Discord] for the tip!

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Upgrade A 3D Printed CNC Milling Machine By Using It

August 4, 2021 by Danie Conradie 22 Comments

One of the original ideas behind the RepRap project was for the machines to create their own upgrades. That philosophy is shining brightly in [Ivan Miranda] CNC milling machine project, which has been used to upgrade its aluminum and 3D printed frame components to steel.

For precision machining on hard metal, machine rigidity is of utmost importance. [Ivan]’s original CNC mill made extensive use of lightweight aluminum extrusions with 3D printed fittings. The machine worked, but the lack of rigidity was visible in the surface quality of the machine parts. The latest upgrade included a completely new frame from welded steel tubing and heavy aluminum mounting plates. The original machine was used to slowly machine slots in the steel tubes to retain the adjustability of the Z-axis. Some of the 3D printed motor mounts remained, so in the second video after the break [Ivan] used the newly upgraded machine to mill some aluminum replacements.

While this machine might not be perfect, we have to respect [Ivan]’s willingness to toss himself in at the deep end and show all failures and lessons learned the hard way. This project was clearly used as an opportunity to improve his welding and machining skills. His fabrication skills have come a long way from mainly 3D printed projects like the giant tracked tank and screw tank.

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The Man-Machine

July 31, 2021 by Elliot Williams 4 Comments

This week we saw a couple DIY tools for small-run manufacturing at home that help make your life easier if you’re climbing out of the happy bucket and into the pit of despair — when you’re making enough of the item that it’s not fun any more, but you still don’t have the volume to leave the manufacturing to someone else.

The first was an automatic through-hole soldering machine made from a 3D printer. This actually makes sense even if you’re getting boards assembled for you, because through-hole pads are a lot more expensive than SMT parts, and they usually charge per pin. Put a 2×20 pin header on your project, and it can end up costing a lot. Or you can robotificate the solution.

This week’s second solution really caught my eye. PnPassist is machine that turns your PCB around, locates a laser crosshair over the next SMT piece that you need to place, and even has an OLED screen that tells you what to put there. There are many great mechanical design choices here, but what really drew my attention is how well this machine fills a gap between manual and fully automatic pick-and-place.

I know you hate looking back and forth between the board and the schematic or parts list, trying to find just where Q23 is on the darn board, or looking up resistor values. With PnPassist, you still have to do the placing, but with machine guidance. If you don’t have the money or the space for a fully automatic PnP, this is an obvious win, but also for short runs when loading up the reels takes more time than populating the board, this could be a huge win.

I love this kind of human-capability-enhancing machine, and I’m always happy to see a design like this. It reminds me of the very clever Shaper Origin, or even just this handy automatic XY table for drilling many precise holes. In all these cases, there’s some part of the problem that would be hard to solve, require extremely bulky or expensive machinery, or can just be more simply accomplished by a meatbag. But combining machine precision with the human element produces something more than the sum of the parts.

What’s your favorite human-enhancing tool?

3D-Printed Tooling Enables DIY Electrochemical Machining

July 29, 2021 by Dan Maloney 10 Comments

When it comes to turning a raw block of metal into a useful part, most processes are pretty dramatic. Sharp and tough tools are slammed into raw stock to remove tiny bits at a time, releasing the part trapped within. It doesn’t always have to be quite so violent though, as these experiments in electrochemical machining suggest.

Electrochemical machining, or ECM, is not to be confused with electrical discharge machining, or EDM. While similar, ECM is a much tamer process. Where EDM relies on a powerful electric arc between the tool and the work to erode material in a dielectric fluid, ECM is much more like electrolysis in reverse. In ECM, a workpiece and custom tool are placed in an electrolyte bath and wired to a power source; the workpiece is the anode while the tool is the cathode, and the flow of charged electrolyte through the tool ionizes the workpiece, slowly eroding it.

The trick — and expense — of ECM is generally in making the tooling, which can be extremely complicated. For his experiments, [Amos] took the shortcut of 3D-printing his tool — he chose [Suzanne] the Blender monkey — and then copper plating it, to make it conductive. Attached to the remains of a RepRap for Z-axis control and kitted out with tanks and pumps to keep the electrolyte flowing, the rig worked surprisingly well, leaving a recognizably simian faceprint on a block of steel.

[Amos] admits the setup is far from optimized; the loop controlling the distance between workpiece and tool isn’t closed yet, for instance. Still, for initial experiments, the results are very encouraging, and we like the idea of 3D-printing tools for this process. Given his previous success straightening his own teeth or 3D-printing glass, we expect he’ll get this fully sorted soon enough.

Automatic Coil Winder Gets It Done With Simple Hardware And Software

July 25, 2021 by Dan Maloney 11 Comments

We’ve grown to expect seeing mechatronics project incorporate a standard complement of components, things like stepper motors, Arduinos, lead screws, timing belts and pulleys, and aluminum extrusions. So when a project comes along that breaks that mold, even just a little, we sit up and take notice.

Departing somewhat from this hardware hacking lingua franca is [tuenhidiy]’s automatic coil winder, which instead of aluminum extrusions and 3D-printed connectors uses simple PVC pipe and fittings as a frame. Cheap, readily available, and easily worked, the PVC does a fine job here, and likely would on any project where forces are low and precision isn’t critical. The PVC frame holds two drive motors, one to wind the wire onto a form and one to drive a lead screw that moves the form back and forth. An Arduino with a CNC shield takes care of driving the motors, and the G-code needed to do so is generated by a simple spreadsheet that takes into account the number turns desired, the number of layers, the dimensions of the spool, and the diameters of the wire. The video below shows the machine going through its paces, with pretty neat and tidy results.

Being such a tedious task, this is far from the first coil winder we’ve seen. Some adhere to the standard design language, some take off in another direction entirely, but they’re all instructive and fun to watch in action.

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