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LT-PAM: A TOUGH PNEUMATIC ARTIFICIAL MUSCLE FOR ABOUT FIVE DOLLARS

A soft actuator that contracts under air pressure, assembled from silicone tube, braided sleeve and printed plugs for roughly five dollars in parts.

by Naniwa K, Sugimoto Y, Nakanishi D, Masuda Y

FULL CAD BOM FIRMWARE DOCS

RoboticsOpen-hardware

Built with3D printing

difficulty
●●●○○
time
an evening
license
CERN-OHL-P-2.0 (hardware), CC BY 4.0 (documentation)
repo
repo FINISHED0 stars

WHAT YOU’LL NEED

1
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COMPAREE VERDICT

LT-PAM is a McKibben-type pneumatic artificial muscle: a silicone tube inside a braided sleeve that contracts when pressurised, the same principle as the commercial Festo Fluidic Muscle used in soft robotics research. The Hokkaido and Osaka team published it in HardwareX with proper characterisation: force-length tests at three pressures, rupture tests at about 600 to 800 N, and a fatigue test of more than 9,000 pressurisation cycles without catastrophic failure. Load-bearing ends are crimped metal clamps, with no structural glue. The material cost is genuinely low: about 800 yen or five US dollars per 150 mm actuator, excluding reusable tools such as the crimping tool, a 3D printer and an air supply up to 0.8 MPa. The single thing most likely to go wrong is underestimating the air supply: 0.8 MPa is not a bicycle pump, and the paper's own safety guidelines say never to exceed it. If you are exploring soft actuation or need a dozen muscles for a walking robot, this is exactly what you want; if you have no pneumatics experience or compressor yet, the real entry cost is higher than the headline figure.

GOOD TO KNOW

  • —STL files, Autodesk Inventor CAD sources, a CSV bill of materials and an assembly video are on Zenodo.
  • —The HardwareX paper contains the full bill of materials, assembly procedure with photographs, and performance characterisation data.
  • —No firmware — this is a purely mechanical/pneumatic actuator.
  • —Hardware files are CERN-OHL-P-2.0 (permissive) and documentation is CC BY 4.0 — both allow commercial use with attribution, with no share-alike requirement.
  • —You need a compressed air source capable of 0.8 MPa (roughly 8 bar or 116 psi) and a crimping tool for hose clamps.
  • —The 5-dollar figure is marginal material cost per 150 mm actuator — it excludes the crimping tool, 3D printer access, and the air compressor.

Parts to buy

4 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • Silicone tubeFind
  • Braided sleeveFind
  • Stainless hose clampsFind
  • One-touch pneumatic fittingsFind

Can I build this?

PrintABS end plugs and assembly holders (STL files provided)
Buysilicone tube, braided sleeve, stainless hose clamps, one-touch pneumatic fittings
Tools3D printer, crimping tool for hose clamps, compressed air source to 0.8 MPa
Skillsbasic pneumatics and 3D printing; reading an academic paper helps
Timean evening per actuator once you have the workflow down
Cost5 dollars per actuator in parts; compressor and tools are the real outlay
SafetyCompressed air at 0.8 MPa is a real hazard — eye protection mandatory, use rated fittings, and clamp hoses properly or they will whip loose under pressure.

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

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Gallery

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Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Read the HardwareX paper (The paper contains the full bill of materials, assembly photographs, and performance data — start there, not the STL files.)
  2. 2.Download the CAD and STL files from Zenodo (Autodesk Inventor source files, STLs for the end plugs and mounting holders, and the CSV bill of materials.)
  3. 3.Source the silicone tube and braided sleeve(The paper specifies the tube inner diameter, wall thickness, and sleeve braid angle — match those or the contraction ratio will be wrong.)
  4. 4.Print the ABS plugs(The plugs are ABS so their layer lines can be smoothed with ABS cement for a better seal; holders can be PLA, ABS or resin.)

Resources

Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.

KNOWN ISSUES

  • The 5-dollar cost is material only — you need a compressor capable of 0.8 MPa, a crimping tool, and 3D printer access, none of which are cheap if you are starting from zero.
  • Cheap pneumatic fittings will leak or blow off at 8 bar; use rated one-touch fittings and crimp the hose clamps properly or you will spend the evening chasing leaks.
  • The contraction depends on the braid angle of the sleeve: the authors' sleeve starts at about 32 degrees and gives about 25 percent contraction. A different sleeve will behave differently, so match the specification.
  • The paper characterises a 150 mm actuator; scaling to a different length changes the force and contraction behaviour in ways that are not linear.
  • Compressed air at this pressure is a real hazard — wear eye protection, secure all hoses, and do not put your face near a pressurised actuator.
  • If you have never worked with pneumatics before, budget time to learn about pressure regulation, safe fittings, and leak testing before you build a dozen of these for a robot.

Can I use PLA for the end plugs instead of ABS?

The authors print the end plugs in ABS and smooth their layer lines with ABS cement to improve the air seal, so stick with ABS for the plugs. The mounting holders can be printed in PLA, ABS or resin.

What air pressure do I actually need?

The paper tests to 0.8 MPa (8 bar, 116 psi). You can run it at lower pressures for less force, but you need a compressor and regulator that can safely deliver the rated pressure.

Is this safe for a prosthetic or wearable robot?

The paper does not address wearability or medical safety, and 8 bar of compressed air near skin is a hazard. This is a research actuator, not a certified medical device.

How does this compare to a Festo Fluidic Muscle?

Same working principle, much lower cost, and you can repair or modify it. The Festo version has tighter tolerances, certified pressure ratings, and comes with fittings — this is the DIY alternative for research or hobby use.

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Discussion1

FROM THE COMPAREE TEAM

The paper reports more than 9,000 pressurisation cycles without catastrophic failure, and each actuator costs about 800 yen in parts. If you were building a quadruped or a soft gripper, how many of these would you need and what would break first?

CompareeTEAM1mo agoedited

Practical notes from our verification: the Zenodo record contains Autodesk Inventor source files, STLs for the stoppers and holders, an editable bill of materials with supplier and part number for every off-the-shelf component, and a how-to-make video showing assembly and operation; the full experimental data is in the open-access HardwareX paper. The cost of about five dollars, or 800 yen, is marginal material cost per actuator, excluding reusable tools such as the crimp tool, a 3D printer and an air supply. If you are starting from zero, the real entry cost is the air supply and the learning curve is pneumatics safety; the authors tested with a regulator up to 0.8 MPa and safety shielding. The parts are Japanese catalogue items (Denka braided sleeve, Monotaro silicone tube, ESCO hose clamps), so outside Japan you may be matching the specs rather than ordering the exact parts. Hardware files are CERN-OHL-P-2.0, a permissive licence. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.

Naniwa K, Sugimoto Y, Nakanishi D, Masuda Y

A research team from Hokkaido University of Science, Osaka Institute of Technology, NIT Matsue College and The University of Osaka published LT-PAM in HardwareX as a low-cost, reproducible alternative to commercial pneumatic muscles. They tested it properly — three pressure levels, tensile strength up to 600–800 N and more than 9,000 pressurisation cycles — rather than just posting a demo.

Star the project on GitHub

DISCLAIMER

  • Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
  • Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
  • Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
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