Yeah, but at <$500k, they can rent it out for $60/hour and recoup expenses in a year. Even if we bump it up to $100/hour to cover administrative costs, that's cheap enough to be accessible for a lot of average citizens to use.
I can think of a few things where printing 50 of them in an hour would be adequate to recoup a $100 equipment rental.
Car parts, computer cases (built-in heatsinks), rock climbing gear (not sure printed metal is strong enough for this one), sculptures, gun receivers (again, there are strength problems), matching door knobs and faucets for houses, prosthetic frames (to be later encased in silicone)... I'm sure there's more.
I would consider using it anywhere I would be looking at CNC-ed metal, especially for one off parts/prototypes. A lot of the cost of CNC is programming and fixturing, which 3D printing technologies save.
Much of the toolpath programming/selection/etc could be "automated" the same way that its automated for FDM printers. But then you would lose some of the "quality" advantage and likely increase tool wear.
But the reverse is also true of 3d printing, frequently I've wanted more control of some particular aspect of the printing job, but existing slicing packages make that very difficult. For example, just slow down the printing along one edge (rather than a whole layer), or change the infill for one particular area, or more detailed temp control of "inactive" nozzles, or just more options during nozzle switch (aka pause for 20 seconds to cool the inactive 10C while heating the active, then wipe both).
Correct on the accuracy, but you can design parts with features like undercuts and cavities on 3D printing that are either not possible, or much more expensive, to CNC.
Not every metal part requires the 0.001" tolerance you can get with CNC as well.
I look at it as another technology that can be selected when the parameters make sense for it. I'm more familiar with plastic technologies, for them I switch between FDM, SLS, SLA, Polyjet and Injection Molding depending on:
- Forecasted quantity
- Time to market needed
- Price constraints
- Accuracy and surface finish required
- Design requirements
Each technology has it's own advantages and disadvantages.
It's the running costs. If you want to make a lot of the same part and need a 5 axis mill, they have to be operated by technicians which are extremely expensive and they can't work on anything else.
Make a lot of parts on a printer and you spend a little more time designing the part and time to tune the settings (which might be done depending on the material you use) and you're off and printing and just paying for print time. Not cheap, but cheaper than paying techs at mid-scale.
I can think of a few things where printing 50 of them in an hour would be adequate to recoup a $100 equipment rental.