1/4" Air Tubing

[BudB]

I'm missing something...............I'm installing an air cylinder to raise and lower my drill press table. As speed is not important I'm using 1/4" flexible tubing. I bought NPT brass adapters for 1/4" tubing which included an "adapter" to place inside flexible tubing to allow proper sealing. My issue is the adapter is designed to tubing with an inside diameter of .190". Thus far the only tubing I can find is polyethylene tubing with a ID of .170". While I can force the adapter into the tubing it is then too large to pass through the ferrule and nut. Any ideas of what tubing I should be looking for?

[gellfex]

I don't understand, McMaster has dozens of different kinds of 3/16 ID 1/4 OD flex tubing. Last time I messed in this sandbox I bought 1/8 npt to barb fittings and used crimp on sleeves or those spring wire clamps.

[paul463]

Try air brake tubing from an auto/truck parts store.

[Corbettprime]

Or try U S Plastics

[Doozer]

All the kool kids are using push-to-connect
tubing fittings. Some good ones are Legris
and SMC. Parker makes them too, but they
are all brass and kind of bulky.
I like to get them from McMaster Carr or
AutomationDirect. No inner tube thingy
is required.

-Doozer

[Arcane]

If only there was a way to make a ferrule...

[CCWKen]

I'm using the push connectors for my mister setup. So far it's held up to 70+ PSI but it hasn't gone through a hot summer cycle yet. The only thing that bites me is all the fittings and tubing are METRIC. I got everything off eBay and Amazon.

[Ed ke6bnl]

NO inside fitting just use push to connect like Doozer says may want to get hose for air brakes or air bags.

[wdtom44]

"Push to connect" are so fast and easy I can't see messing with anything else that takes a bunch of small parts unless you have a special application that requires a more firm or secure connection. I have used "push to connect" a lot, on the machines I used to maintain when working, and never had a problem. Even saw some in Lowes. Read McMaster for compatible types of tube and fittings.

[JoeLee]

Isn't using air going to be spongy as far as movement?

JL................

[Willy]

Try air brake tubing from an auto/truck parts store.

All the kool kids are using push-to-connect
tubing fittings. Some good ones are Legris
and SMC. Parker makes them too, but they
are all brass and kind of bulky.
I like to get them from McMaster Carr or
AutomationDirect. No inner tube thingy
is required.

-Doozer

Yes lots of options.
Both of the two above are good choices that I have used a lot in the past with very good results. The determining factor is probably going to be ease of local availability.

[wdtom44]

[QUOTE=JoeLee;1220031]Isn't using air going to be spongy as far as movement?

Flow controls may help this. Look in McMaster for them. Install so the flow is controled when air is being exhausted, free flow when entering. With one on each side of the cylinder you can "tune" a cylinder down to a slow and controlled movement.

[Yondering]

Isn't using air going to be spongy as far as movement?

JL................

Yes, and potentially dangerous too unless some sort of damping mechanism is included; air is very springy. I work with a lot of air cylinder mechanisms, and the force applied tends to be a lot like a spring; it's fairly easy to control the force but much more difficult to control the rate of motion, and free travel usually results in high velocity and a hard bang against the end stop. Air systems are not at all like hydraulic systems where motion can be easily controlled through flow restrictions.

With that said, air brake line as suggested earlier is the way to go. You can use either push connect or traditional threaded brass connections. The push connect fittings like ccwken showed work well, but they don't have to be metric. Only reason his are is because that's what the cheap chinese sellers are offering; good quality connectors from reputable suppliers are available in both inch and metric sizes.

[JoeLee]

[QUOTE=wdtom44;1220096]

Isn't using air going to be spongy as far as movement?

Flow controls may help this. Look in McMaster for them. Install so the flow is controled when air is being exhausted, free flow when entering. With one on each side of the cylinder you can "tune" a cylinder down to a slow and controlled movement.

Yes, you can control the flow but if there is any sticking or binding the pressure will build until there is enough force to move the part and then it will jump. If you can pump air through the system then why can't you pump fluid through it?

JL..............

[JoeLee]

I had a shop a long time ago that had a floor hoist in it. It haden't been used for years.
I found an H head that fit the cylinder and bolted it up. Hooked up my air supply to the valve system that was still in place so it would work.
It did work but was really low on oil and there was a lot of air in the system.
The first time I went to raise a car on it I'm standing there holding the lever listening to the air fill they cylinder and nothing was happening.
All of a sudden the car jumped up about 3 feet and then stopped. I held the lever as the air continued to flow. All of a sudden the car jumped up another 2 1/2' and the cylinder slammed as it topped out, the car bounced a little. Scared the crap out of me, all I could think of is the cylinder coming out of the floor and the car crashing over me. When I went to let it down I'm listening to all the air being released and all of a sudden the car dropped about 3'. Air is not good to move things.

JL..............