Pneumatic/Hydraulic Cylinder

by LoialOtter, published

Pneumatic/Hydraulic Cylinder by LoialOtter Jan 16, 2013
0 Share
Download All Files

Thing Apps Enabled

Order This Printed View All Apps


Liked By

View All

Give a Shout Out

If you print this Thing and display it in public proudly give attribution by printing and displaying this tag.

Print Thing Tag

Thing Statistics

17908Views 3155Downloads Found in DIY


This is an operational pneumatic/hydraulic cylinder. The main goal with this was to make a cheap and easy to produce cylinder for use on interesting projects. It's also a proof of concept.

I've used central vacuum tubing as it's very cheap ($6.50/12ft section) and is rigid. Other pipe can be used and the OpenSCAD files have variables at the beginning to customize the parts.

There are mounting holes (optional) on the front and back faces along with (again, optional) the sides of both the front and back.

This was developed and built using my overly large 3d printer called Tiny. See https://ottersoft.ca/ for details and news.


Materials Required:

  • one of each part
  • a length of shaft (current files for 1/4" drill rod) see bellow for length
  • 2 o-rings for the piston (i used 3/16" thick by aprox 1 1/2" diameter inside)
  • 2 o-rings for the cylinder head (i used 1/16" thick by about 1/4" diameter inside)
  • 2 1/4" tapered thread fittings to the hose you'll use
  • 6 fasteners to pin the head and base in place
  • 2 fasteners, one for the piston and the other for the rod end to pin them in place
  • some E6000 or Shoe Goo to seal/glue parts together
  • oil or lubricant

The tube length needs to be 52mm longer than the full stroke (this will be 52mm shorter than the cylinder length)

Print one of each part as solid as you can. A good option is either 100% infill or 30% with minimum 6 outside layers and 6 top and bottom layers. I also suggest going with slightly smaller layer-height (i used 0.25 on a 0.5mm nozzle) because the end prints are stronger.

The piston and rod end both have holes for drilling through the shaft on one side. Drill through that hole and through the shaft with a small drill bit (1/8" or 2mm for instance) then pull the shaft out and drill for a close fit on the fastener you're using. Also drill the plastic to just under the size of the fastener to allow threading.

O-rings need to be seated on the piston and inside the shaft hole in the cylinder head. The ones in the head can be a bit tricky but I found that inserting the rod til just shy of the ring and then shoving the o-ring in place works.

Before assembling, the cylinder tube needs to be prepared. Slide the cylinder base and head onto either end of the tube and line up the fitting holes to where you need. There are marks along the edge of those two parts which point to where the holes will be located on the tube. The holes are 10mm in so scribe that distance. Drill with a small bit to start then widen for a tight fit with the head of the fastener you're using. If you have countersunk fasteners this is a good time to use them.

Test the piston to see how well if fits. If it doesn't enter the piston easily, you may need to take a small round-file and make the o-ring seats a little deeper.

The base can be attached permanently so glue as well as fasten it onto one end.

Pass the rod through the cylinder head while it's out of the cylinder and then glue and fasten the piston onto the end of the rod.

Lubricate and slide into the tube. If the system works correctly, you can glue and fasten the head in place.

Insert the fittings, remove some and glue, then tighten them down completely.

Test, tweak and enjoy!

More from DIY

view more

All Apps

3D Print your file with 3D Hubs, the world’s largest online marketplace for 3D printing services.

App Info Launch App

Auto-magically prepare your 3D models for 3D printing. A cloud based 3D models Preparing and Healing solution for 3D Printing, MakePrintable provides features for model repairing, wall thickness...

App Info Launch App

Kiri:Moto is an integrated cloud-based slicer and tool-path generator for 3D Printing, CAM / CNC and Laser cutting. *** 3D printing mode provides model slicing and GCode output using built-in...

App Info Launch App
KiriMoto Thing App

With 3D Slash, you can edit 3d models like a stonecutter. A unique interface: as fun as a building game! The perfect tool for non-designers and children to create in 3D.

App Info Launch App

Print through a distributed network of 3D printing enthusiasts from across the US, at a fraction of the cost of the competitors. We want to change the world for the better through technology, an...

App Info Launch App

Quickly Scale, Mirror or Cut your 3D Models

App Info Launch App

3D Print a wide range of designs with Treatstock. Easy to use tools to get the perfect result. The global 3D printing network that connects you with high-quality and fast working print services nea...

App Info Launch App

how do you adjust it to 2 in, I printed the parts from your files and they are 1 3/4 inch, how do I go about changing the measurements

Looks very nice, I'd be interested to see what kind of pressure differential it can handle across the piston and if there are leaks around/through the piston. Tie rods would be stronger maybe for the end caps?

the instructions never give length of the rod used

Very nice!
Might I suggest a few possible improvements?

  • IIRC, Mobile o-rings shouldn't be squished between the cylinder and the piston.
    Instead they should be chosen ever so slightly larger than the ID of the cylinder (so they naturally press lightly against it), and sit in a groove in the piston that allows a small but significant radial play (a groove that is too deep, possibly way too deep).

The air pressure behind the o-ring will push it against the side of the groove and against the exterior wall.

The OD of the piston needs to be greater than the final mid diameter of the o-ring (Ideally, as close as possible to the cylinder ID)

The bottom of the groove needn't be toroidal of course, although it could help with printing and strength.
In this configuration, you will have way less friction, and should be able to cope with less-than-perfect tubes easily, as well as not needing to file the grooves to size at all.

  • The same (in the opposite direction) can be applied to the rod o-rings (loose in their grooves, and clinging lightly to the rod)

  • You could use o-rings to seal the ends, rather than glue (the right side of the set screw obviously), to allow servicing (squishing is fine, but loose & oversized should work of course)

  • Making the piston rod-hole blind would eliminate glue altogether.

Best of luck!

Great ideas; I'll print out a new one with some of the changes to see how it works. I should've thought of making the setscrews blind, that one is so obvious.

I was wondering if this was possible. I have a bunch of o-rings I bought just for this purpose. Can't wait to try it out.

Video of operation?

Man this is awesome! I can't wait for a progress update about how well it works. Are you planning on using it pneumatically or hydraulically?

P.S. I'm building a large 3d printer similar to your tiny, so thank you for posting so much about your process :-)

I'm planning on using this for pneumatics but was going to try hydraulics when i get a chance. I did notice that there are some leaks near the pin screws but I haven't glued those in yet so that's expected. So far, though definitely far from perfect, they work pretty well for use as a pump. I'll model up a pair of reed valves that use the same fittings and see what kind of pressure they can get up to.