Makerspace i3Detroit was the recent recipient of a free yet non-functioning CNC router. While out of commission when received, the device’s mechanical components and motors appeared to be in operational condition, plus it had a large work surface. The decision was made to get the CNC up and running for now, with the eventual goal of turning it into a plasma cutter.

First, they booted up its (Windows 95) computer and replaced a power supply on the controller. An adapter board for the controller was then built using info from this Arduino Forum post, allowing the router to be controlled with an Arduino Mega running grbl firmware. 

Although there is still some work to do, it can be seen happily jogging along in the video below, and appears well on its way to becoming a usable machine!

In order to get a good cut with a CNC router, the cutting tool speed needs to be properly set. Since his CNC didn’t come with RPM feedback, Troy Barbour came up with his own solution using an Arduino Nano along with an IR emitter/sensor pair.

The spindle was set up with a single reflective surface, enabling it to sense one pulse per revolution that is sent to the Arduino at up to up to 30,000 RPM. To ensure accurate measurement, the device was programmed using an interrupt, meaning that if another process is running, it will temporarily drop what it’s doing and count the incoming pulse.

RPM is displayed on a tiny OLED screen, which shows both an RPM number as well as a dial indicator for quick reference.

Build an optical RPM indicator for your CNC router with an Arduino Nano, an IR LED/IR photodiode sensor and an OLED display for less than $30. I was inspired by eletro18’s Measure RPM – Optical Tachometer Instructable and wanted to add a tachometer to my CNC router. I simplified the sensor circuit, designed a custom 3D-printed bracket for my Sienci CNC router. Then I wrote an Arduino sketch to display both a digital and analog dial on an OLED display.

You can see it in action below, and find build instructions and code on Barbour’s write-up.

Forget sourcing parts for your next project from some fancy neighborhood hardware store. If you really want to show your hacker chops, be like [HomoFaciens] and try a Dumpster dive for parts for a CNC machine build.

OK, we exaggerate a little – but only a little. Apart from the control electronics, almost everything in [HomoFacien]’s build could be found by the curb on bulk-waste pickup day. Particle board from a cast-off piece of flat-pack furniture, motors and gears from an old printer, and bits of steel strapping are all that’s needed for the frame of a serviceable CNC machine. This machine is even junkier than [HomoFacien]’s earlier build, which had a lot more store-bought parts. But the videos below show pretty impressive performance nonetheless.

Sure, this is a giant leap backwards for the state of the art in DIY CNC builds. but that’s the point – to show what can be accomplished with almost nothing, and that imagination and perseverance are more important for acceptable results than an expensive BOM.

With that in mind, we’re throwing down the gauntlet: can anyone build a CNC machine from cardboard and paperclips?

A vise, a hacksaw and file, some wrenches – the fanciest tools [HomoFaciens] uses while building his DIY hardware store CNC machine (YouTube link) are a drill press and some taps. And the bill of materials for this surprisingly precise build is similarly modest: the X- and Y-axes ride on cheap bearings that roll on steel tube stock and aluminum angles; drives are threaded rods with homemade encoders and powered by small brushed DC gear motors; and the base plate appears to be a scrap of ping-pong table. The whole thing is controlled by an Arduino and four H-bridges.

The first accuracy tests using a ball point pen for tooling are quite impressive. [HomoFaciens] was able to draw concentric circles eyeball-accurate to within a few tenths of a millimeter, and was able to show good repeatability in returning to a point from both directions on both the X- and Y-axis. After the pen tests, he shows off a couple of other hardware store tooling options for the Z-axis – a Proxxon rotary tool with a burr for engraving glass; a soldering iron for cutting styrofoam; and a mini-router that works well enough to cut some acrylic gears.

We’re impressed by this build, which demonstrates that you don’t need a fancy shop to build a CNC machine. If you’re getting the itch to jump into the shallow end of the CNC pool, check out some of the builds we’ve featured before, like this PVC CNC machine, or this $250 build.

[Thanks, ThunderSqueak]