Pneumatic Muscles
Intro: Pneumatic Muscles
Pneumatic Muscles, or Air Muscles are simple, cheap and extremely powerful. Applications range from machinery, robotics to wearables. Air muscles have no stickction and have a weight to strength ratio like no other linear actuating mechanism. It's weakness is in speed. The speed at which air muscles contract is controlled by how fast air is pumped into the muscle (cfm). So, in order to achieve high actuation speeds, you need large tubes and air controls to get enough air into the muscle quickly.
The assembly I've outlined below is experimental. Pipe fittings weren't meant to be used for this purpose, so please take caution when pumping pressurized air into these assemblies. The muscles I made were used for my Soft Pneumatic Exoskeleton. Air muscles work and are easy to build.
Specifications
max air pressure: 120 psi
suggested lengths: 6"-30"
weight: n/a
strength: n/a
Materials (prices as of 6/29/2008) (materials listed below can be purchased at mcmaster.com)
High-Temperature Silicone Rubber Tubing Soft, 3/8" ID, 1/2" OD, 1/16" Wall
mcmaster.com # 5236K15 | $1.31 per foot
Heavy Duty Polyester Expandable Mesh Sleeving 1-1/2" ID, 3/4" to 2" Bundle Dia, 3'L, Black
mcmaster.com # 9142K34 | $5.83 each
Standard Brass Compression Tube Fitting Adapter for 1/2" Tube OD X 1/4" NPTF Female Pipe
mcmaster.com # 50915K226 | $3.86 each
Standard Brass Compression Tube Fitting Long Nut for 1/2" Tube OD
mcmaster.com # 50915K106 | $2.36 each
Moisture-Resistant Acetal Push-to-Connect Adapter for 5/32" Tube OD X 1/4" NPTF Male Pipe
mcmaster.com # 51055K8 | $1.45each
Standard Brass Compression Tube Fitting Tube Support for 1/2" Tube OD
mcmaster.com # 50915K246 | $7.37 for a pack of 10
Low-Pressure Brass Threaded Pipe Fitting 3/8" Male X 1/4" Female Pipe Sz, Reducing Bushing
mcmaster.com # 4429K522 | $1.78 each
Brass Yor-Lok Tube Fitting Cap for Tubing, 3/4" Tube OD
mcmaster.com # 5272K146 | $8.70 each
Choose-A-Color Flexible Nylon 11 Tubing .106" ID, 5/32" OD, .025" Wall Thickness, Red
mcmaster.com #5635K62 | $0.21 per foot
For each muscle you want to assemble you need:
(1) Silicon tubing cut to length (ex. 12")
(1) Braided sleeving cut to length -1/2" ( ex. 11.5")
(2) Tube Supports (1 pack comes with 10)
(1) Tube Fitting Cap
(1) Tube Fitting Long Nut
(1) Reducing Brushing
(1) Brass Compression Tube Fitting Adapter
Average price per muscle: ~$30
Note: The Tube Fitting Long Nut replaces the Hex nut that the Compression Tube Fitting Adapter comes with.
Pneumatic power and control parts
Valves (mechanical or solenoid)
Pressurized air source ( air reservoir or air compressor)
For pneumatic controls, vexrobotics has a nice starter kit. http://www.vexrobotics.com/vex-robotics-pneumatic-parts.shtml
The assembly I've outlined below is experimental. Pipe fittings weren't meant to be used for this purpose, so please take caution when pumping pressurized air into these assemblies. The muscles I made were used for my Soft Pneumatic Exoskeleton. Air muscles work and are easy to build.
Specifications
max air pressure: 120 psi
suggested lengths: 6"-30"
weight: n/a
strength: n/a
Materials (prices as of 6/29/2008) (materials listed below can be purchased at mcmaster.com)
High-Temperature Silicone Rubber Tubing Soft, 3/8" ID, 1/2" OD, 1/16" Wall
mcmaster.com # 5236K15 | $1.31 per foot
Heavy Duty Polyester Expandable Mesh Sleeving 1-1/2" ID, 3/4" to 2" Bundle Dia, 3'L, Black
mcmaster.com # 9142K34 | $5.83 each
Standard Brass Compression Tube Fitting Adapter for 1/2" Tube OD X 1/4" NPTF Female Pipe
mcmaster.com # 50915K226 | $3.86 each
Standard Brass Compression Tube Fitting Long Nut for 1/2" Tube OD
mcmaster.com # 50915K106 | $2.36 each
Moisture-Resistant Acetal Push-to-Connect Adapter for 5/32" Tube OD X 1/4" NPTF Male Pipe
mcmaster.com # 51055K8 | $1.45each
Standard Brass Compression Tube Fitting Tube Support for 1/2" Tube OD
mcmaster.com # 50915K246 | $7.37 for a pack of 10
Low-Pressure Brass Threaded Pipe Fitting 3/8" Male X 1/4" Female Pipe Sz, Reducing Bushing
mcmaster.com # 4429K522 | $1.78 each
Brass Yor-Lok Tube Fitting Cap for Tubing, 3/4" Tube OD
mcmaster.com # 5272K146 | $8.70 each
Choose-A-Color Flexible Nylon 11 Tubing .106" ID, 5/32" OD, .025" Wall Thickness, Red
mcmaster.com #5635K62 | $0.21 per foot
For each muscle you want to assemble you need:
(1) Silicon tubing cut to length (ex. 12")
(1) Braided sleeving cut to length -1/2" ( ex. 11.5")
(2) Tube Supports (1 pack comes with 10)
(1) Tube Fitting Cap
(1) Tube Fitting Long Nut
(1) Reducing Brushing
(1) Brass Compression Tube Fitting Adapter
Average price per muscle: ~$30
Note: The Tube Fitting Long Nut replaces the Hex nut that the Compression Tube Fitting Adapter comes with.
Pneumatic power and control parts
Valves (mechanical or solenoid)
Pressurized air source ( air reservoir or air compressor)
For pneumatic controls, vexrobotics has a nice starter kit. http://www.vexrobotics.com/vex-robotics-pneumatic-parts.shtml
STEP 1: Place Silicon Tube Into Braided Sleeve
Cut the silicon tube to your desired length.
Cut the braided sleeve to the same length minus 1/2 inch.
Burn the ends of the braided sleeve with a lighter to prevent it from fraying and to give it a lip in the compression sleeve assembly.
Shove the silicon tube into the braided sleeve.
Cut the braided sleeve to the same length minus 1/2 inch.
Burn the ends of the braided sleeve with a lighter to prevent it from fraying and to give it a lip in the compression sleeve assembly.
Shove the silicon tube into the braided sleeve.
STEP 2: Place Tube Fitting Cap
Slide the braided sleeve and tube through the hex nut
Place the tube support inside the silicon tube
Screw the hex nut into the fitting tightly
Place the tube support inside the silicon tube
Screw the hex nut into the fitting tightly
STEP 3: The Other End
Place the braided sleeve and silicon tube through the long nut
Place a tube support inside the silicon tube
Screw the tube fitting adapter into the long nut
Screw the reducing brushing into the adapter
Screw the push-to-connect adapter into the reducing brushing
Place a tube support inside the silicon tube
Screw the tube fitting adapter into the long nut
Screw the reducing brushing into the adapter
Screw the push-to-connect adapter into the reducing brushing
STEP 4: Pump Air Into the Muscle
Place the 5/32" tubing into the push-to-connect adapter
Pump air in.
Pump air in.
40 Comments
JonathanN67 7 years ago
matthew585 8 years ago
i just got all the parts that you have listed and I got 3/8 X 1/2 rubber tubing but then I got the mesh sleeving witch was 1 and a half inch witch was 40mm and it looks pretty big can you help me out like is that the actual size
bowmaster 14 years ago
cheewee2000 14 years ago
bowmaster 14 years ago
lordl9999 13 years ago
did you have any thoughts about how to deliver portable power(e.g. batteries) to the air compressor?
i was thinking about just having a couple of air tanks on the back (kind of like a diver) instead of the compressor, but that might not be enough air if your going for a walk ;) (didn't do any actual calculations yet, so i'm just laying out thaughts/ guessing)
well, did you have any thoughts about that subject?
- and to the guy making this instructable; nice work ;)
cheewee2000 13 years ago
I bought a pony tank (mini scuba tank) so that it could be portable, but never got around to getting the proper regulator to get pressure coming out of the tank at the right psi that i needed, but in theory that should work. At one point I was using mini co2 cartridges, but they only last a few actuations, but are super portable.
good luck!
VVVBATMAN 8 years ago
Hi, I know it has been a while, but I am interested in the use of Co2 cartridges for air muscle use. I would greatly appreciate it if you could explain how you used the cartridges. Thanks!
cheewee2000 8 years ago
I was using emergency bike pumps that run off CO2 cartridges as my valve. They were the only valves I could find that drop the super high pressure in the cartridge down to something more manageable.
VVVBATMAN 8 years ago
Thank you so much for replying,
Do you have a link to one of these valves anywhere on amazon or anything?
Thanks again!
jo'dell1 10 years ago
okura 15 years ago
Even that is a copy of various DIY articles on the net. You can Google for it as ' Mckibben air muscle latex silicone '.
You do'nt even have the courtesy to acknowledge the 'copied' original sources!
It is not correct to enter this for any competition.
cheewee2000 15 years ago
My contribution here is a cheap and simple way to make your own. All the parts are available online and you don't need to fabricate any custom hardware.
Thanks for the positive and constructive comment!
tyscof 10 years ago
jehan60188 12 years ago
thanks!
nidobrito 12 years ago
Pooloop 13 years ago
Pooloop 13 years ago
R3mus 14 years ago
Im going to attempt a mash between this instructable and the other air muscle instructable to get a working device. Now that I know how easy they are to make, I wont spend so much to get one working.
cheewee2000 13 years ago