[monte55]

Ok guys, those of you who are familiar with me, know how I like to make stuff. I have always been fascinated with hydraulics. Here is a cylinder I made from scrap material. A lot of you have lathes and making a piston or a rod or an end cap is not much of a chore. But...trying to make the cylinder with a smooth bore that is accurate is difficult if not impossible for the home shop.
My neighbor had a new deck put on the front of his house and for ballisters they used 3/4 inch round black aluminum tubes. There was scrap left over and being who I am, I saw visions of what I could make. The tubes are 3/4 inch OD... .654 ID with a very smooth bore. On the box it said this was 6061 extruded aluminum.
With this size bore and at air pressure of 100 psi you can expect about 33 lbs of push from this little cylinder, which is more than enough power to open large tool box lids, robotics, etc (your imagination is your only limitation).
The first pictures show the end caps I made from aluminum and the rear end cap and piston have been grooved to accept O rings to seal better. This is a single acting cylinder and no seal at the rod end. The rod is 1/4 inch.
The threaded hole in the rear cap is 1/8 inch pipe thread which is very common. The fitting is 1/8 inch pipe thread on one side and 1/4 inch compression fitting on the other which makes it very handy to use 1/4 inch aluminum, copper, or flexible plastic line for your air supply. The last picture shows the cylinder assembled. There is no rod end because I have not yet decided how I will apply this.
At first, I had thought I might TIG the caps on but I was afraid that I may slightly distort the cylinder from the heat. If you will notice, on the end caps, enough of the cap is inserted into the cylinder that I could pin it in place with 1/8 inch roll pins. That is why I put an O ring on the rear end cap and the pin is between the O ring and the brass inlet fitting.
One good thing about finding this resource (as far as the cylinder) is you can custom make any length you need to fit your exact need. I am going to check into a larger ballister tubes for more power.

I hope some of you will find this useful.
Nick
PS I suggest you use a small restrictor orifice at the air inlet so the rod will not slam out too fast.

[DSL PWR]

Good job. Just make sure the tubes are anodized (looks like they are) or they will wear out quickly.

[vulcom1]

I'm into RC modelling and once in a while I make a cylinder or two. Mainly for retracts. You mentioned you pinned the end caps after you made them. A suggestion is maybe on your lathe if you can is turn internal and external threads. The walls are thin with what I made before so I used a fine pitch. Somewhere around 32 tpi and not very deep. After I used loctite for securing. I would post a pic but the model has been long gone.
Just a suggestion and I like your work.
John

[steve323]

Nice looking air cylinders.

What are you planning to use for valves? Do you have a source for electrically controlled valves at a reasonable price?

Steve

[ImanCarrot]

Very nice n neat.

Would oil be better than air though? Am thinking from a failure point of view- decompresing oil is a bit safer?

Not criticising, just a thought

[monte55]

Very nice n neat.

Would oil be better than air though? Am thinking from a failure point of view- decompresing oil is a bit safer?

Not criticising, just a thought

To operate hydraulicly would be great but then I'd have to have a pump etc.
Actually I may use it to open the cab on my r/c Skidsteer bot I made a few years back. It's on youtube . If you want to see it in action put GOT BOT? in the youtube search bar.

[ImanCarrot]

Ahh! I see

Seen that You Tube video before and was well impressed then and now with it... you have waaay too much time on your hands sir hehe.

Respect.

[Greg Maxwell]

Just thought I would post my pics, I fabricated these from 5/8 seamless tubing, I threaded the ends caps and the ID of the tube 1/2 NC thread.
I made 5 of these.
http://i229.photobucket.com/albums/e...nderparts2.jpg
http://i229.photobucket.com/albums/e...nderparts1.jpg
http://i229.photobucket.com/albums/e...nderparts3.jpg
Installed in the Tractor.

http://i229.photobucket.com/albums/e...ffandhoses.jpg

[fpmoolman2]

I am in need of a pneumatic cylinder of about 3 Bar, so I found this post and then went to make dinner when an idea hit me: Old automotive shock absorbers!! I love using the chromed bars from those shocks for just about everything, because they are hard and strong and most fitment centres have a whole heap out back that they are happy to share. Also, because of the smoothness, you can run them in plastic bearings with little wear. And I have access to a big heap of plastic from when a plastics factory closed down. It’s not fair, I know.

What makes them really handy for cylinders is the pressure tube, which is a smooth bore tube found inside the housing. Very thin walled, though, so I will put steel tube around this tube, maybe with silicone sealant between the tubes.

As for attaching the end-caps, I will make them square in the axial view, and drill holes on the corners so that I can draw the end-caps toward each other with threaded rod.

About them shocks:
1: If you want a great centre-punch, drill a hole into one end of a short length of the chromed bar so that it will accept HSS round bar. Sharpen the bar and braze in place. I quenched mine and they work great. Apparently, injector tips also make great punch tips. Make yourself a good few at a time, it’s more time-effective that way.

2: Here’s how to salvage your shocks.
A: Put on your oldest, dirtiest pair of work trousers and boots. I normally tie plastic bags around my shoes, so I look like a hillbilly surgeon. Set a tarpaulin or some sand or whatever at a far end of the garden. Old oil sometimes stinks and this is always a messy operation. Hot oil is great for burning skin and eyes, so wear long sleeved gloves and a full face mask. A vice is also a good idea if you have a mobile one. Or you can bolt your vice onto a redundant paving brick. Keep a bucket handy, and be prepared to discard your dirty clothes outside the house.
B: Do the whole lot at one time, as it saves on soap.
C: For each chock, pull the rod out all the way and make a cut on the non-rod end until oil starts running out or you see smoke. That means that oil is running out.
D: Pump the oil into the bucked by working the rod in and out a few times.
E: Cut the endcap off.
F: Pull the inner sleeve and the rod out, as they will now be loose.
G: Job done. I only keep the inner sleeves and rods.

Important: While sparks from an abrasive cutter will normally just bounce off a windscreen, they will stick and burn when they are coated with hot oil. Ditto your skin.

I shall post pics, brothers.