CNC Machining

One of the shows that shaped me is Movie Magic. It may have been the start of Reactive. Most of the episodes were a lot of fun and informative to boot. Some of them were not as much fun, but still informative.

This may have been the first time I ever came across a CNC machine, which was used to carve the detail work on Ra's sarcophagus for the original Stargate film. At the age of 13, how could I *not* have been taken by this wicked piece of tech. I added it to the mental want list. Since 1994, when the episode aired, the hobbyist DIY movement has morphed into the Maker movement. Technology that turns 2D into 3D continues to become increasingly inexpensive. Autodesk launched 123D, which is a free 3D design app. Microcontrollers are ubiquitous for those who know to look for them.

The tech that turns those design files into solid, actual protoypes and projects have absolutely plummeted in price due to the cult of Makerdom and economies of scale. While printing seems to be the darling of Makers, something that is undeniable is that final concepts are almost always produced with subtractive practices, like CNC milling, rather than additive methods, like 3D printing.

It was time to get a CNC for the shop. For the unaquainted, a CNC machine does exactly what you see in the video. The basic setup is a router mounted to the moving gantry of a Cartesian robot; a robot that moves in the X, Y and Z planes. By converting the design file into code that the robot understands, the router tip removes material from your blank and keeps going until all that's left is a solid representation of your digital design.

There are caveats, of course. With the basic X, Y and Z setup, generally called a 3-axis CNC, the cutting envelope (the box in which material can be placed and cut) is considered to be 2.5 axis. The distinction means that what you carve can't have undercuts. There are 5 and 6-axis machines that allow the router itself to pivot. A full machine has an A, B and C axis in addition to X, Y, and Z. These full machines haven't gotten to consumer level pricing as yet. What's important here is that all CNC tech has been cut to decimal costs compared to where they used to be. The machine in the video, speculatively, cost well over a hundred-grand. While it was notably large, similar tech can now be had for a round a thousand. Stretching it to the size and power capable of cutting out Ra's resting place may double the price.

The brilliance is not only speed, but the intelligence of the machine. What I mean by that, or rather the software with which we control, is the capacity to potentially do an entire project with only one router bit or or endmill. This is the brilliance of Computer Numeric Control. Knowing that you have a flat bottomed bit one-eighth inch in diameter, the machine will be able to cut any bull nose, recess, groove, slot, channel, relief or profile so long as all the detail is at or larger than one-eighth inch. Consider the implications just for furniture work. Instead of swapping bit after bit and repositioning and clamping work pieces, one bit is smart enough to go precisely where it needs to and make as many passes as are required in order to make the carving.

On our path to being able to easily construct shape, and believing that the ultimate finish for any project is a subtractive method, I got swept up in the wave of CNC construction. Luckily, everyone benefits.

The first shop machine acquired was a small unit. The drive electronics on this one are actually based on the Arduino microcontroller platform that has become so popular in hobby, art and and most every Maker circle. It is capable of sending signals in the correct format to run the motors. Those signals are then tremendously amplified by integrated circuits (chips) that are designed to send power to the motors to then move the router where it needs to be.

Unfortunately, this minor task has turned in to an obsession. When the kit was purchased, it lacked electronics. It was just a sliding gantry with no control. Our preferred driver board solution was no where to be seen. It had been produced in small quantities and was then no longer available anywhere. This was a serious hit to the plan, since the mechanical bits had already been ordered. Lesson learned: buy the complicated parts first.

Turns out the control board was an open source project created by Bart Dring at buildlog.net. He was good enough to make the files available. I took the file, made some small tweaks, thickened up the copper on the board to better handle the heat and power, and asked Bart for permission to sell them. I was granted it. I also offered him a percentage of the sales and he agreed to accept a more than fair (to me) amount. With that in the bag, production began. They are now available on the shop page.

This is really where the site gained its mission from. If the capacity is there to turn ideas people have in their heads into actual objects they can hold, then giving access to that capacity to as many people as possible is incredibly important. Who knows who the next Dean Kamen will be? Or Henry Ford, Tesla, or Musk.

As the state of invention increasingly gets refined, more exacting prototypes are required. Not only do they match precisely what is needed, but things designed in digital 3D space also reduce waste and time spent finishing in actual 3D space. Routers and printers are a tremendous boon to the stage property niche, but they are a world-changer far beyond that.

To see the work we are currently doing in this field check out

• our storefront where we have electronic controls for hobby CNC setups
• and our corresponding set of instructions on building the electronics.