Physics change aware scale transposed prototyping

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See also strongly related page: Applicability of macro 3D printing for nanomachine prototyping

This is about using macroscale manufacturing techniques to prototype and/or investigate
future (not yet buildable) atomically precise nanosystems made out of gemstone like compounds.
For this not to be pointless and the results to have at least some semblance of actual future nanosystems
one must be attentive to the changes of physics that occur at these much smaller nanoscales.

For why this makes sense at all despite
natures life (for the most part) not doing cogs-n-gears at the nanoscale
see pages: Macroscale style machinery at the nanoscale & Why gemstone metamaterial technology should work in brief

Under-engineering & over-engineering

(wiki-TODO: Venn diagram of what applies to macroscale what applies to nanoscale and what applies to both scales.)

Avoid under-engineering (forcing macroscale over-engineering)

Tolerate over-engineering (as macroscale under-engineering just does not work)

Example #1 (vdW force):
There is no way around over-engineering some parts that otherwise just wouldn't work at the macroscale.
One can at bets try to play some tricks. E.g. absence of the tremendously useful vdW force as on the macroscale can be faked …

  • very poorly by gravity (unidirectional and constant long range force vs omnidirectional short range force)
  • semi-decently by magnets (requires the integration of magnets - manual prefabrication with what is vitamins in RepRec context)
  • perhaps decently by an sufficiently air sucking end-effector

Example #2 (stiffness):
Also one cannot avoid massively over-engineer in strurdiness and bulkiness,
due to macroscale actually being worse for cog-n-gear style machiners than nanoscale in terms of the stiffness aspects.
but to understand this one needs some important context as presented below in the next section.
More discussion on this in section after next.

Important context - right intuition on stiffness

The nominal operation speed scaled effective stiffness of nanosystems
is vastly higher than in macroscale systems due to …

  • diamond being vastly stiffer than even the best steel
  • proposed operating speeds being ~1000x slower than macroscale robotic motions
  • these two effects multiply

It is way too easy to get thoroughly misled on this aspect of nanoscale physics for at least two reasons …

  • (1) there's a scaling law of "lower stiffness of smaller machinery" that says that absolute stiffness actually falls with size
  • (2) molecular dynamics simulations show diamondoid machine element mechanisms jiggle around like jelly.

But …

(wiki-TODO: Eventually define nominal operation speed scaled effective stiffness mathematically precisely! Using the same relative deflections across scales law.)

Macroscale systems can't be made anywhere near as filigree as nanosystems could be made

Given the context form preceding section it should be no longer feel outlandish to read the following:
Even the best macroscale materials are soft like jelly compared to systems made out of crystolecules operated at proposed speeds.
Even if one would pick the best available materials like spring steel or such
one cannot possibly engineer as filigree as that will be possible with atomically precise gemstone bases nanostructures and nanomachinery.
Adding to that are gravitational loads present on the slightly larger (meters) macroscale that need to be counteracted against.

Caveat: For nanosystems that are supposed to do mechanosynthesis one still will
want to stay bulky at the nanoscale in order to keep thermal motion amplitudes minimal.

Caveat: Micro-systems may not me slowed down as much as nanosystems (e.g. due to infinitesimal bearings)
so the difference is not as big there. Especially not compared to future macroscale gem-gum materials that in a sense
carry the microscale properties up to the macroscale.

Overview over various macroscale manufacturing methods for the prototyping

Materials & methods & their PROs & CONs

Shoestring budget DIY home accessible:

  • FFF/FDM 3D printing (CON bigger parts & less accurate layers, PRO more strong plastics options)
  • SLA (resin) 3D printing (PRO smaller parts & more accurate layers parts, CON lesser strong plastics options)
  • plastic injection molding (there are some affordable DIY machines around by now 2025,
    (PRO some tough plastics can be used that hardly can be printed as they do not stick well HDPE, POM, PTFE, PP, PA, … ~ 3D printer filament printability)
  • casting resin (G27 2compunent PU - EU legal access restrictions for private customers?, CON lesser strong plastics options)
  • Meh: laser-cutting (via maker-space, mostly way too restrictive in possible geometries)

Industrial / Via a service:

  • industrial metal 3D printing (too expensive, cheapest most viable: aluminum)
  • subtractive CNC milling (too expensive)
  • Aluminum die casting
  • MEMS manufacturing (many CONs: very expensive, difficult to access, too much design restrictions, hard to debug as too small to touch)

Exotic / Experimental:

  • Galvanic methods like (electroforming) …
  • DIY Solvent evaporation casting?
  • DIY compression molding?
  • DIY pre-filled cast metal powder melting under inert gas (small parts)
  • DIY geopolymer casting (possibly only for casting metals

Issues concerns related to manufacturing methods for part preproduction

Issue of manual effort in basepart preproduction:
All the lost cast methods are likely too much manual effort.
Bad for prefabrication automation.
Lost cast methods are especially unavoidable for high melting temperature metals (including aluminum alloys ~660°C).
Low melting metals (like tin and zinc) that are somewhat castabel into
high temp resistant polymer molds (silicone) are too soft for their severe weight.
Brass is borderline but already high melting temperature.

Issue with high permanent loads:
Permanent high load (as might be needed in prototypes)
can be a huge problem for plastic polymers. Creep & micro-cracking till eventual fracture.
Most plastic polymers are at least somewhat long term UVlight vulnerable.

Issue of stability for history and for the duration of prototyping:
To get a long term history surviving capable artifact eventually getting made a prototype in metal would be needed. For long duration taking prototyping sufficiently performant polymers will hopefully suffice.

Micro-to-makro mesoscale prototyping

Micro-to-makro mesoscale manufacturing seems to be of especial interest
as larger robotic systems won't need warehouse amoiunts of space
(expense in renting space out, and risk of disposal due to being in the way)
Easiest accessible and cheapest here (as of 2025) is high resolution SLA resin printing.

Neither fish nor fowl - multi application case issue

Prototypes systems may turn out to potentially also be useful in other contexts such as e.g. …

  • robotic in space systems and
  • local DIY home robotic systems

… but this will put a forcing function on
culling back on intentional over-engineering for nanoscale compatibility.

Calling for the integration of "vitamins" like e.g.
small screws that'd become subatomic in size when scaled down.

Calling for the removal of some things.
(wiki-TODO: Remember what I had in mind here.)

Allowed types of cheating

Adding in metal ball/roller bearings where, when scale transposed down to nanoscale, the balls/rollers would become smaller than atoms may actually be an OK case as such ball bearings could be replaced by a sliding sleeve bearing. Basically replacing the ball/roller bearing with nothing. Some cost in friction but still no wear for the AP nanoscale system.

The macroscale system may critically need a bearing as just sliding friction under gravitational loads alone may be on a quickly self-destructive level. At least for FDM/FFF plastic 3D printed structures that can most certainly be the case. Author speaking from experience.

This is a disallowed vitamin from a RepRec local at home DIY self relicating pick-n-place robot though. So a slight conflict of interest here. Relating to the "neither fish nor fowl" topic section.

Related

External links

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