I think many people intuitively understand that 3D printers have a more computer or electronics-like potential for a Moore's Law-ish progression to commoditized home units.
To the people who who like to say: "Pfft, why is 3D printing such a big deal, CNC's been around for ever?..." I'll say the following:
- CNC machinery requires expensive bits and tool-heads that wear out.
- CNC machinery requires a certain minimum amount of space to move it's tools and the work to access it from various directions.
- CNC machinery requires a certain size and mass that it's difficult to get below, and power of motors to do the work.
- CNC machinery often requires constant sprays of baths of liquid coolant/lubricant which is messy.
- CNC machinery requires solid billet or bar stocks which are expensive, and wasteful. (tons of chips you can't re-use)
- CNC machinery can only work with different materials in the same piece if they're joined or forged together beforehand.
On the other hand:
- 3D printers only have one "tool", the print head, or the laser,
- 3D printers can be much smaller in size/mass/footprint/weight for the same size of work-piece as a CNC machine.
- 3D printers do not need constantly circulating lubricant.
- 3D printers could in theory re-use the powders or waste feedstocks. And such powders and feedstocks are much easier to transport/ship/sell in a consumer/commodity model with large economies of scale (i.e. standardized bags, buckets, boxes, or bottles of powder, or spools of plastics) since the only variable is different amounts of them that people might want, instead of different sized semi-custom forgings or billets.
- 3D printing can in theory shift between materials in the same workpiece.
- 3D printing can make shapes, voids, and interlocking pieces that are impossible for cutting, machining, or a CNC machine to produce.
Yes, CNC machinery can be "shrunk" and made more cheaply, and that's already showing some signs that is going to be part of the "revolution". And I know there are probably always going to be certain kinds of parts that will only work if CNC'd from solid metal stock. However, CNC still comes up against certain physical limitations that make them less suitable for ubiquitous use and distribution. You need billets and raw forgings to start with, you can't pour the shavings or chips back into the CNC machine and get more parts, the machine needs to be a certain minimum size to move it's tool heads and/or the work platform around in multiple axes. It has to be a certain weight, size and strength to handle the pressure and torque of the motors to cut into the work and the friction of the tools.
