A Rotary Axis CNC Machine

There’s a certain class of parts that just can’t be made on a standard 3-axis mill, nor with a 3D printer or a lathe. These parts — weird screws, camshafts, strange gears, or simply a shaft with a keyway (or two) — can really only be made with a rotary axis on a CNC machine. Sure, you could buy a rotary axis for a Haas or Tormach for thousands of dollars, or you could build your own. That’s exactly what [Adam Zeloof] and [Matt Martone] did with their project at this year’s World Maker Faire in New York. It’s the Rotomill, a simple three-axis CNC machine, with a rotary axis, that just about anyone can build.

The design of the Rotomill uses a standard, off-the-shelf Makita rotary tool for the spindle, and uses leadscrews to move the X and Z axes around with NEMA 24 stepper motors. The A axis — the rotary bit — is driven through a worm gear, also powered by a NEMA 24. Right now this provides more than enough power to cut foam, plastic, and wood, and should be enough to cut aluminum. That last feat is as yet untested, but the design is open enough that a much more powerful spindle could be attached.

The software for this machine is a bit weird. For most CNC machines with a rotary axis, the A axis is treated as such — a rotary axis. For the Rotomill, [Adam] and [Matt] are generating G Code like it’s a normal Cartesian machine, only with one axis ‘wrapped’ around itself. This is all done through Autodesk HSM, and a properly configured Arduino running GRBL makes sense of all this arcane geometry.

It’s a great looking machine, and the guys behind it say it’s significantly less expensive than any other machine with a rotary axis. That’s to be expected, as it’s basically a five axis mill with two axes removed. Still, this entire project was built for about $2000, and some enterprising salvage and hacking could bring that price down a bit.

DrawBot Badge Represents the CNC World in Badge Design

Badges come in all shapes and sizes, but a badge that draws on a stack of Post-It notes is definitely a new one. The design uses three of the smallest, cheapest hobby servos reasonably available and has a drawing quality that creator [Bart Dring] describes as “adorably wiggly”. It all started when he decided that the CNC and mechanical design world needed to be better represented in the grassroots demo scene that is the badge world, and a small drawing machine that could be cheaply made from readily available components seemed just the ticket.

Two arms control the position of a pen, and a third motor lifts the assembly in order to raise or lower the pen to the drawing surface. Gravity does most of the work for pen pressure, so the badge needs to be hanging on a lanyard or on a tabletop in order to work. An ESP32 using [Bart]’s own port of Grbl does the work of motion control, and a small stack of Post-It notes serves as a writing surface. Without the 3D printed parts, [Bart] says the bill of materials clocks in somewhere under $12.

We’ve seen similar designs doing things like writing out the time with a UV LED, but a compact DrawBot on a badge is definitely a new twist and the fact that it creates a physical drawing that can be peeled off the stack also sets it apart from others in the badgelife scene.

Wood Shines in this SCARA Robotic Arm Project

[igarrido] has shared a project that’s been in the works for a long time now; a wooden desktop robotic arm, named Virk I. The wood is Australian Blackwood and looks gorgeous. [igarrido] is clear that it is a side project, but has decided to try producing a small run of eight units to try to gauge interest in the design. He has been busy cutting the parts and assembling in his spare time.

Besides the beautifully finished wood, some of the interesting elements include hollow rotary joints, which mean less cable clutter and a much tidier assembly. 3D printer drivers are a common go-to for CNC designs, and the Virk I is no different. The prototype is driven by a RAMPS 1.4 board, but [igarrido] explains that while this does the job for moving the joints, it’s not ideal. To be truly useful, a driver would need to have SCARA kinematic support, which he says that to his knowledge is something no open source 3D printer driver offers. Without such a driver, the software has no concept of how the joints physically relate to one another, which is needed to make unified and coherent movements. As a result, users must control motors and joints individually, instead of being able to direct the arm as a whole to move to specific coordinates. Still, Virk I might be what’s needed to get that development going. A video of some test movements is embedded below, showing how everything works so far.

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Turning a Cheap Engraver into a Decent PCB Mill

We know, we know. Getting PCBs professionally fabricated anymore is so cheap and easy that making them in-house is increasingly becoming something of a lost art. Like developing your own film. Or even using a camera that has film, for that matter. But when you’re in Brazil and it takes months for shipments to arrive like [Robson Couto] is, sometimes you’re better off sticking with the old ways.

[Robson] writes in to tell us how he decided to buy a ~$150 CNC “engraver” kit from an import site, in hopes that it would allow him to prototype his designs without having to use breadboards all the time. The kit turned out to be decent, but with a series of modifications and a bit of trial and error, he’s improved the performance significantly and is now putting out some very nice looking boards.

The primary hardware issues [Robson] ran into were in the Z axis, as some poor component selections made the stock configuration wobble a bit too much. He replaced some flimsy standoffs as well as swapping in some bushings he salvaged from dead inkjet printers, and the movement got a lot tighter.

Despite the fact that the version of Grbl flashed onto the engraver’s cloned Arduino Uno supports Z leveling, it’s not actually enabled out of the box. [Robson] just needed to add some extra wiring to use the spindle’s bit as a probe on the copper clad board. He also went ahead and updated to the latest version of Grbl, as the one which ships with the machine is fairly old.

He wraps up the post by going through his software workflow on GNU/Linux, which is useful information even if you’ve taken the completely DIY route for your PCB mill. If you’d like to know more about the ins and outs of milling your own boards, check out this excellent primer by [Adil Malik].

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Custom Coaxial Dust Collector Makes CNC Router a Clean Machine

Everyone loves firing up that CNC router for the first time. But if the first thing you cut is wood, chances are good that the second thing you cut will be parts for some kind of dust shroud. Babysitting the machine and chasing the spindle around with a shop vac hose probably isn’t why you got it in the first place, right?

Trouble is, most dust-management designs just don’t get the job done, or if they do, they obstruct your view of the tool with a brush or other flexible shroud. [Jeremy Cook] figured he could do better with this coaxial dust collector, and from the practically dust-free cuts at the end of the video below, we think he’s right. The design is a two-piece, 3D-printed affair, with a collar that attaches to the spindle and a separate piece containing the duct. The two pieces stick together with magnets, which also lets the shroud swivel around for optimal placement. The duct surrounds the collet and tool and has a shop vac hose connection. In use, the vacuum pulls a ton of air through small opening, resulting in zero dust. It also results in the occasional part sucked up from the bed, so watch out for that. [Jeremy] has published the STL files if you want to make your own.

We’re pretty impressed, but if you still feel the need for a physical shroud, check out this shaggy-dog design that seems to work well too. Or you could just throw the whole thing in an enclosure.

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A CNC Woodworking Tool That Does The Hard Parts

Drawn along in the wake of the 3d printing/home shop revolution has been the accessibility of traditional subtractive CNC equipment, especially routers and mills. Speaking of, want a desktop mill? Try a Bantam Tools (née Othermachine) Desktop Milling Machine or a Carvey or a Carbide 3D Nomad. Tiny but many-axis general purpose mill? Maybe a Pocket NC. Router for the shop? Perhaps a Shapeoko, or an X-Carve, or a ShopBot, or a… you get the picture. [Rundong]’s MatchSticks device is a CNC tool for the shop and it might be classified as a milling machine, but it doesn’t quite work the way a more traditional machine tool does. It computer controls the woodworker too.

Sample joints the MatchSticks can cut

At a glance MatchSticks probably looks most similar to a Pocket NC with a big Makita router sticking out the side. There’s an obvious X-axis spoilboard with holes for fixturing material, mounted to a gantry for Z-axis travel. Below the big friendly handle on top is the router attached to its own Y-axis carriage. The only oddity might be the tablet bolted to the other side. And come to think of it the surprisingly small size for such an overbuilt machine. What would it be useful for? MatchSticks doesn’t work by processing an entire piece of stock at once (that what you’re for, adaptable human woodworker) it’s really a tool for doing the complex part of the job – joinery – and explaining to the human how to do the rest.

The full MatchSticks creation flow goes like this:

  1. Choose a design to make on the included interface and specify the parameters you want (size, etc).
  2. The MatchSticks tool will suggest what material stocks you need, and then ask you to cut them to size and prepare them using other tools.
  3. For any parts which require CNC work the tool will help guide the user to fixture the stock to its bed, then do the cutting itself.
  4. Once everything is ready for final assembly the MatchSticks will once again provide friendly instructions for where to pound the mallet.

In this way [rundong], [sarah], [jeremy], [ethan], and [eric] were able to build a much smaller machine tool without sacrificing much practical functionality. It’s almost software-like in it’s focus on a singular purpose. Why reinvent what the table saw can do when the user probably already has access to a table saw that will cut stock better? MatchSticks is an entire machine bent around one goal, making the hard stuff easier.

It’s worth noting that MatchSticks was designed as an exploration into computer/human interaction for the ACM Conference on Human Factors in Computing Systems so it’s not a commercial product quite yet (we’re eagerly waiting!). For a much more in depth look at the project and its goals and learnings the full research paper is available here. Their intro video is down after the break.

Thanks [ethan] for the tip!

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Getting Resourceful to Build A Home CNC

CNC really is a game changer when it comes to machining. If your motor skills or ability to focus aren’t all there, you don’t need to worry – the computer will handle the manual task of machining for you! These builds are popular for DIYers to undertake, as they enable the production of all manner of interesting and advanced parts at home once they’re up and running. However, parts to build a CNC machine can get spendy; [Brenda] decided to take a recycling-based approach to her build instead (Youtube link).

The build uses motion parts from an old silicon wafer fabrication machines, an IKEA table for the work surface, and a scavenged computer to run the show. Control is via the popular LinuxCNC software, a viable candidate for anyone doing a similar build at home. In a neat twist, the holes for hold-downs on the work table were drilled by the machine itself!

Overall it’s a tidy build, broken up over a series of videos that each go into great detail on the work involved.  Interested in your own bargain CNC build? Check out this $400 setup.

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