Suitable mechanisms
From apm
This page is basically just a list of mechanisms that
could be suitable and useful for future advanced diamondoid gemstone based nanosystems.
Contents
What makes mechanisms "suitable"?
Unlike in macroscale machinery with machine parts at the lowermost possible size limit
there is no space for tiny screws that are much more tiny than the functional parts to clamp together.
(Functional parts is here referring to housings for gearboxes, essential machine element components, and such.)
Thus there is a need for designs that differ quite a bit from the conventional macroscale metal part engineering.
See the design principles listed on the page: RepRec pick-and-place robots (GemGum).
Under the lens of these constrains a particular set of
mechanisms/machine-elements emerges as especially promising.
This page features a collection of such mechanisms.
Macroscale side benefit
These mechanisms also allows for interesting 3D printable mechanics that
can cope without any metal screws whatsoever. A few big 3D printable screws suffice.
Whole classes of mechanisms
- Rolling with static friction being absent and surfaces not being flat (atomic bumps) calls for gear-bearings.
Peculiarly the periodic table of gearbearings - Enforced equipartitioned distribution of speed differences over several layers.
See: Infinitesimal bearings
Related: Atomically precise bearings
External links
Bearings and Gearings
- conical/tapered gearbeaings (with applied pre-tension)
- conical/tapered ravigneaux gearboxes: https://www.flickr.com/photos/65091269@N08/51163799216
- Wobblemotors: Moineau PCP pumps run partially in reverse with the core only rotating and the outside only wobbling
- PCP gearboxes based on the wobble-motor principle?
- ( Coupled cycloid wobble-rotors like this: https://twitter.com/Kuu3_Mechanics/status/1657680117680979969 – 9,10,11,12 )
- rotative to reciprocative conversion via a straight-line-hypocycloid rather than a classical crankshaft mechanism
Like this: https://digital.library.cornell.edu/catalog/ss:29272012
Or like this: https://commons.wikimedia.org/wiki/File:Inversion_of_Hypocycloid_Gear_Train_Ellipse_and_Straight-line_Mechanism.gif or [1]
The essence: http://www2.mat.dtu.dk/people/J.Gravesen/MoineauPump/Hypo2_1.html
vice versa needs multi-phase drive for defined direction
Couplings
- https://en.wikipedia.org/wiki/Coupling#Oldham
- Oldham coupling inspired gear coupling:
Two linear-rack-gearbearings with each two rollers to define a plane. Those two sandwiched atop each other with
their rolling direction arranged 90° to each other. Thus they have the same exact effect as an Oldham coupling. But with internal rolling rather than sliding. - (Schmidt coupling - this needs a lot of pins (ideally gear-bearings) thus listed in the likely unsuitable section further below)
CV type joints
- Tracta joint: https://en.wikipedia.org/wiki/Constant-velocity_joint#Tracta_joints
- Tripod joint: https://en.wikipedia.org/wiki/Constant-velocity_joint#Tripod_joints
- Double Cardan joint: https://en.wikipedia.org/wiki/Constant-velocity_joint#Double_Cardan
Doube cardan is two universal joints that are each individually not CV - (Rzeppa & Thompson down in the likely unsuitable section)
Joints
- Hirth joints: https://en.wikipedia.org/wiki/Hirth_joint <<< these are extremely useful
- Spline joints: https://en.wikipedia.org/wiki/Spline_(mechanical)
- fir-tree joints (generalization/optimization of dovetail joints) https://en.wikipedia.org/wiki/Dovetail_joint
- rotate extruded fir-tree-joints allowing for torsion or bending around a virtual axis
For quick-release:
- Panic snap: https://en.wikipedia.org/wiki/Panic_snap
- Snap shackle: https://en.wikipedia.org/wiki/Shackle
Chains
- Sprockets: https://en.wikipedia.org/wiki/Sprocket
- Roller chains: https://en.wikipedia.org/wiki/Roller_chain
- Gear teethed chains
- Attachment chains
- Rigid chains: https://en.wikipedia.org/wiki/Rigid_chain_actuator
For end-effectors and preceding
- Chucks https://en.wikipedia.org/wiki/Chuck_(engineering)
- Parallel plane fast acting grippers
- Vise like grippers: https://en.wikipedia.org/wiki/Vise
- Whippletree: https://en.wikipedia.org/wiki/Whippletree_(mechanism)
- Classical mechanical differential (for robot wrists): https://en.wikipedia.org/wiki/Differential_(mechanical_device)
- SCARA geomerty: https://en.wikipedia.org/wiki/SCARA
- Parallel manipulator: https://en.wikipedia.org/wiki/Parallel_manipulator
The general principle. Not just the given example. Parallel SCARA, CoreXY, ... all parallel. - successive onion shell peel-off tube-axle and bevel-gear serial mechanics principle
Special screwdrivers end-effector mechanisms that:
- put zero torque on the manipulated structure ("space screwdriver")
- decouple tensioning from unloaded screwing structure ports (wiki-TODO: explain that principle more clearly with sketch)
These screwdrivers end-effector mechanisms shall operate on "tension-force hydrants".
See ReChain frame systems.
Likely useful for tensioning and other things
- Turnbuckle: (but rather for length adjustment when load is displaced) https://en.wikipedia.org/wiki/Turnbuckle
- Differential screws: https://en.wikipedia.org/wiki/Differential_screw
- excenter tensioners
- knee-lever-tensioners (de: Kniehebelspanner) — <https://de.wikipedia.org/wiki/Kniehebel> — <https://de.wikipedia.org/wiki/Kniehebelpresse
- mechanisms that act as intended breakage points but that are reversible ...
- Rolamite (but modified to gearbearings): https://en.m.wikipedia.org/wiki/Rolamite
Positive displacement pumps
- PCP pumps: https://en.wikipedia.org/wiki/Progressing_cavity_pump
Good resources for modeling here: http://www2.mat.dtu.dk/people/J.Gravesen/MoineauPump/HypoEpi4_3.html
and here various configs: http://www2.mat.dtu.dk/people/J.Gravesen/MoineauPump/ - conventional piston pump: https://en.wikipedia.org/wiki/Piston_pump
but operated like described on page vacuum handling - ( Roots blower: https://en.wikipedia.org/wiki/Roots-type_supercharger )
Misc
- "parts for nano-machines" collection on Thingiverse:
https://www.thingiverse.com/mechadense/collections/51015/things
Probably too many small pins, too low stiffness, and better solutions present
- Sarrus linkage: https://en.wikipedia.org/wiki/Sarrus_linkage
- Paucellier linkage: https://en.wikipedia.org/wiki/Peaucellier%E2%80%93Lipkin_linkage
- Schmidt coupling: https://en.wikipedia.org/wiki/Schmidt_coupling
- Classical cycloidal drive: https://en.wikipedia.org/wiki/Cycloidal_drive
Very many bearings desirable here.
Unsuitable CV type joints:
- Rzeppa joint: https://en.wikipedia.org/wiki/Constant-velocity_joint#Rzeppa_joints
2-DOF rolling balls not suitable for atomic scale due to atomic bumpiness. - Thompsonjoint: https://en.wikipedia.org/wiki/Constant-velocity_joint#Thompson_joints
Too intricate. Many small parts.
Related
More generally: Principles that can help avoid the need for very many small screws:
- Simplifying complexity of connection mechanisms by combining form closure and tension.
See: ReChain frame systems - Clamping housings with just one single big screw.
See: Tension redirection principle
Most generally: The design principles listed on page RepRec pick-and-place robots (GemGum).
