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Effector Lab

Effector library

Rack-and-pinion parallel gripper for an open hobby arm

A printed parallel gripper that replaces a hobby arm's stock jaw: two clamps on a gear rack, about 84 mm of stroke, camera mounts.

Parallel gripperNativeEntrantCERN-OHL-P-2.0, Apache-2.0, CC-BY-4.0

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Facts

Kind
Parallel gripper
Class
Open hardware (buildable)
Capabilities
  • pinchholds a part between two opposed tips or pads
Mount
The hobby arm's wrist servo (replaces its stock jaw).ISO pattern: none (own interface)
  • Camera holders for common depth cameras are included upstream.

Specifications

SpecValueBasisSource
Full stroke84 mmSourcedSource
Gripping force120 NSourcedSource
Speed14 mm/sSourcedSource
Repeatability0.5 mmSourcedSource

Simulation

Status
NativeNative simulation model
Model source
Converted from the upstream URDF (relicensed 2026-08-24; the community variant is not used).
Fidelity
Rigid model
Model
1 actuator · 864 g
Note
The description has no actuator; the clamp servo is modelled from the published 120 N grip.
Tournament
Entrant1 entrant spec in the effector tournament.

Compile and attach gate

Each entrant spec is built in the tournament's shared scene on every training part. One nominal episode per built part (no placement error, seed 0) is information, not part of the gate.

Rack-and-pinion parallel gripper for an open hobby arm

GATE PASSED
Primitive
pinch
Actuators
1
Mass
864 g
Reach
134.8 mm
Opening
n/a
Training partGateHeld (nominal)Nominal outcomePenetrationWhy refused
BlockbuiltnoSlipped during lift0.43 mm
Steel slugbuiltnoPushed away on close0.33 mm
Hex standoffbuiltnoMissed grasp0.03 mm
L-bracketbuiltnoMissed grasp0.04 mm
Pipe teebuiltnoMissed grasp0.57 mm
Flanged bushingbuiltnoMissed grasp0.19 mm

Held on no training part in the nominal episode.

Licence

Licence rating: green. Full attribution: see the credits page.

Files

FileTypeSizeLicenceChanged
camera_holder.stlassets/effectors/library/gripper-2f-hobby-parallel-84/print/camera_holder.stlPrint file145.2 kBCERN-OHL-P-2.0as upstream
clamp.stlassets/effectors/library/gripper-2f-hobby-parallel-84/print/clamp.stlPrint file37.8 kBCERN-OHL-P-2.0as upstream
gear.stlassets/effectors/library/gripper-2f-hobby-parallel-84/print/gear.stlPrint file55.8 kBCERN-OHL-P-2.0as upstream
gear_rack_a.stlassets/effectors/library/gripper-2f-hobby-parallel-84/print/gear_rack_a.stlPrint file22.1 kBCERN-OHL-P-2.0as upstream
gear_rack_b.stlassets/effectors/library/gripper-2f-hobby-parallel-84/print/gear_rack_b.stlPrint file23.6 kBCERN-OHL-P-2.0as upstream
main_frame.stlassets/effectors/library/gripper-2f-hobby-parallel-84/print/main_frame.stlPrint file90.3 kBCERN-OHL-P-2.0as upstream
nail.stlassets/effectors/library/gripper-2f-hobby-parallel-84/print/nail.stlPrint file2.7 kBCERN-OHL-P-2.0as upstream
gripper-2f-hobby-parallel-84.xmlassets/effectors/library/gripper-2f-hobby-parallel-84/sim/gripper-2f-hobby-parallel-84.xmlSimulation file (derived)1.9 kBApache-2.0modified
m0.objassets/effectors/library/gripper-2f-hobby-parallel-84/sim/meshes/m0.objSimulation file (derived)36.7 kBApache-2.0modified
m1.objassets/effectors/library/gripper-2f-hobby-parallel-84/sim/meshes/m1.objSimulation file (derived)17.3 kBCERN-OHL-P-2.0modified
m2.objassets/effectors/library/gripper-2f-hobby-parallel-84/sim/meshes/m2.objSimulation file (derived)17.4 kBCERN-OHL-P-2.0modified

Each file links to its copy in the repository. Licence texts sit next to them in LICENSES/. What changed is on the credits page.

Upstream

Linked, not mirrored

What, and whySizeLink
Assembly CAD (5.7 MB): linked, not mirrored.5.7 MBPinned file