Trash Can CNC Gets a Stepper Upgrade

[HomoFaciens] is back at the bench again and working on improvements to his cheap and simple CNC machine.

The video below will no doubt remind you about previous versions of [HomoFaciens]’ CNC builds, which we’ve covered in depth. With an eye to spending as little as possible on his builds, most parts are recovered from e-waste, with a fair amount of Dumpster diving thrown in. For this upgrade, the salvaged brushed DC motors with their signature gap-toothed encoder disks are replaced with genuine bipolar steppers. The primary intention of his build is to learn (and teach) as much as possible, so he spends a good amount of time going over steppers and their control – how to determine phase wiring, how to wire up the not-salvaged-but-still-cheap drivers, directional control, and half-stepping. The mechanics are decidedly dodgy, but there are clever expedients aplenty – we especially like the oil cup fabricated from a brass tube and a bolt with a hole drilled in it. Everything just works, and the results to expense ratio is hard to beat.

While we appreciate the upgrades here, we’re still keen to see how junky his other trash can CNC can get. And we’re still waiting on the paper clip and cardboard challenge.

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CNC Scrapbooking with a Raspberry Pi

It is perhaps a surprise that the widespread adoption of CNC machinery in the home has not come from 3D printing or desktop mills, but as a quiet revolution in the crafting industry. CNC cutters for plastic or card have been around for quite a while now, and while the prospect of cutwork greetings cards might not set all maker pulses racing these cutters do have significant untapped potential in other directions. Perhaps you have to own a carburetor whose gaskets have been unavailable since the 1960s to truly appreciate that.

[James Muraca] has a KNK Force, something of an object of desire in the world of desktop CNC cutters. The computer inside the Force is a Raspberry Pi, so of course [James] set about investigating its potential for running his own software. His progress so far is on GitHub, a web interface through which you can upload and cut an SVG file, but his plans are more ambitious. He hopes to turn his machine into a complete PCB manufacturing station, able to both cut the PCB, and with the addition of a vacuum attachment to pick and place components.

The KNK Force is an interesting machine not just because it is powered by a Raspberry Pi. Its cutter head is a rotary tool with a Z axis, so it can perform more heavy-duty and complex cutting tasks than its competition. In addition it has a camera built-in, and it is this feature that [James] hopes to use in his PCB project.

We’ve covered plenty of cutter projects before, from projects turning CNC machines and pen plotters into vinyl cutters to using a cutter as a laser engraver and even cutting solder paste stencils with one. We look forward to further progress on [James’s] project.

Turn Your Laser Cutter Into An SLS 3D Printer

Filament style 3D printers are great, but typically are rather size limited. Laser sintering printers offer huge print beds, but also come with quarter million dollar price tags. What are we supposed to do? Well, thanks to OpenSLS, it might just be possible to turn your laser cutter into your very own SLS 3D printer.

We’ve covered OpenSLS a few times before, but it looks like it’s finally becoming a more polished (and usable) solution. A research article was just recently published on the Open-Source Selective Laser Sintering (OpenSLS0 of Nylon and Biocompatible Polycaprolactone (PDF) that goes over the design and construction of a powder handling module that drops right into a laser cutter.

The team has created the hardware to turn a laser cutter with a bed size of 60cm x 90cm into an SLS printer. The beauty? The majority of the hardware is laser cut which means you already have the means to convert your laser cutter into a 3D printer.

The design files are available on their GitHub. Hardware will likely cost you around $2000, which is peanuts compared to the commercial laser sintering printers. There is tons of info in their article — too much for us to cover in a single post. If you end up building one, please let us know!

Turn Your $10 Dollar Mouse Into A Fancy $10 Dollar Mouse With CNC

We feel it’s healthy to cultivate a general desire for more neat tools. That’s just one of the reasons we like [doublecloverleaf]’s retro PC mouse. It certainly meets the requirement, the first computer mouse was wooden, and the mouse he used as the guts for this is so retro it belongs in the dollar bin at the thrift store.

To begin with, [doublecloverleaf] took a picture of the footprint of his aged, but trustworthy laser mouse. Using the photo in SolidWorks he built a model of the circuit board, and with that digitized, a mouse that suited his aesthetics around it. The final model is available on GrabCAD.

Edit: Woops, looks like we accidentally slandered a great Slovenian community CNC project. Check out the comments for more info. Original text in italics. 

Next came the CNC. It looks like he’s using one of those Chinese 3040 mills that are popular right now. The electronics are no good, but if you luck out you can get a decent set of mechanics out of one. He did a two side milling operation on a wood block, using four small holes to align the gcode before each step, and then milled the bottom out of aluminum. Lastly, he milled the buttons out of aluminum as well, and turned a knurled scroll wheel on his lathe.
The end result looks exceedingly high end, and it would be a hard first guess to assume the internals were equivalent to a $10 Amazon house brand mouse.

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DIY Shapeoko 3 Enclosure

Setting up a desktop CNC brings along two additional problems that need to be resolved – noise and dust. [Nick] upgraded from a Shapeoko2 to the Shapeoko3 and decided to build a fresh dust and noise proof enclosure for his CNC , and it turned out way better than he had anticipated.

When trying to build something like this, aluminium extrusions seem like the obvious choice for the structure. Instead, he opted for low-cost steel frame shelving units. The 3mm thick steel frame results in a nice rigid structure. The top and bottom were lined with 18mm thick MDF panels. For the two sides and back, he choose 60mm noise dampening polyurethane foam lined with 6mm MDF on both sides, and held together with spray adhesive and tight friction fit in the frame.

The frame was a tad shallower and caused the spindle of the Shapeoko3 to stick out the front. To take care of this, he installed an additional aluminium frame to increase the depth of the enclosure. This also gave him a nice front surface on which to mount the 10mm thick polycarbonate doors. The doors have magnetic latches to hold them close, and an intentional gap at the top allows air to enter inside the enclosure. A 3D printed outlet port was fixed to the side wall, where he can attach the vacuum hose for dust collection. The final step was to add a pair of industrial door handles and a bank of blue LED strip lights inside the enclosure for illumination.

It’s a simple build, but well executed and something that is essential to keep the shop clean and dampen noise.

Teaching a CNC New Tricks

Computer Numeric Control technology has been around for a long time. It’s at the heart of our 3D printers, laser cutters / etchers and CNC milling machines. They all work the same way — you begin with a CAD program and make some type of design. Then the computer converts the file into a set of XYZ coordinates and moves a tool head accordingly. Now let us pose to ourselves a most interesting question. What if you reversed the process? What if you could take a CNC’d object and convert it into XYZ coordinates?

This is precisely what [dave] is attempting to do. He’s made a basic CNC outfit and installed encoders on the steppers. He then manually moves the tool head to trace out an object. At the same time, the encoders are feeding the coordinates to a computer for recording. The idea is to replay the coordinates to see if the CNC can replicate the object.

Judging from the video below, the project is a success!

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Brushed DC Servo Drive

Brushless DC motors, and their associated drive electronics, tend to be expensive and complicated. [Ottoragam] was looking for a cheaper alternative and built this Brushed DC motor servo controller and the results look pretty promising. Check out the video after the break.

He needed a low cost, closed loop drive for his home-brew CNC. The servo drive is able to supply a brushed DC motor with up to 7 A continuous current at up to 36 V which works out to about 250 W or 1/3 HP. It does closed loop control with feedback from a quadrature encoder. The drive accepts simple STEP and DIRECTION signals making it easy to interface with micro controllers and use it as a replacement for stepper motors in positioning applications. All of the control is handled by an ATmega328P. It takes the input signals and encoder data, does PID control, and drives the motor via the DRV8701 full bridge MOSFET driver. There’s also some error detection for motor over-current and driver under-voltage. Four IRFH7545 MOSFETs in H-bridge configuration form the output power stage.

This is still work in progress, and [Ottoragam] has a few features pending in his wish list. The important ones include adding a serial interface to make it easy to adjust the PID parameters and creating a GUI to make the adjustment easier. The project is Open Source and all source files available at his Github repository. The board is mostly surface mount, but the passives are all 0805, so it ought to be easy to assemble. The QFN footprint for the micro controller could be the only tricky one. [Ottoragam] would love to have some beta testers for his boards, and maybe some helpful comments to improve his design.

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