Hardware Store CNC Machine is Remarkably Precise

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]

Cutting styrofoam with a CNC machine and turning it into aluminum

One of the most popular ways of turning an object trapped inside the world of a computer into a real, metal object is the art of lost wax, or lost foam casting. In this process, a full-scale model of the object to be made in metal is crafted in either foam or wax, placed in a pile of sand, and burned away by molten metal.

[ptflea] over at the Bamberg, Germany hackerspace Backspace came up with a very clever build that automatically cuts foam into the desired shape, ready to be taken out to the backyard foundry. The build is based around an old flatbed scanner and a hot wire cutter. The old scanner conveniently had  an equal number of steps per axis, so attaching an Adafruit motor shield and replacing the old control electronics was just an issue of finding the correct resistors.

Software control is provided by a Processing app [ptflea] whipped up and is able to carefully cut very delicate shapes that even the steadiest hand would have trouble with.

Making stuff out of styrofoam is cool and all, but the real goal for this project was setting things on fire and melting old heatsinks. The styrofoam molds were placed in a bucket full of sand, and the furnace – a few ytong bricks, a crucible, and a propane burner – started to melt some aluminum. The molten aluminum was poured onto the mold and after cooling, the makers of Backspace had a few very cool aluminum trinkets.

A nice build that is able to produce some very nice metal objects. We suspect, though, that a higher-density foam (something along the lines of blue or green insulation sheets, if they have those in Germany) could produce an even higher level of detail if you’d like to build your own.

Videos after the break.

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