Author Topic: Model Engine air system  (Read 6044 times)

Offline chucketn

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Model Engine air system
« on: June 07, 2013, 12:33:36 AM »
You all know Iím a relative newbee at this model engine building hobby. So new, I havenít built a boiler of any type to run my basic engines. I run all my creations on compressed air. I donít even have a respectable air system in my shop. Just an old Hausfield-Campbel portable compressor and a tin of various adapters to connect my meager creations (only 4 runners to date!).
So, I want to standardize the method in which I connect air to my little beauties. Today, I purchased a 5 gallon air tank, air hoses, a regulator, and various adaptors with the idea of making a portable air system that can be easily connected to any air source for recharging, and have a regulated output.
One of the hoses I purchased is a small hose with knurled (not hex) connectors that also came with a couple of adaptors to connect it to 3/8Ē air fittings. The knurled fittings are threaded 1/8-27 NPT. I have chosen this size fitting to connect my engines.
That brings me to my question(s). I know there are taps for this thread widely available, and dies not so widely available. I plan to turn 1/8-27 NPT on my lathe? Is this thread tapered? Does anyone have an unused tap and die set for this thread they donít need? Are there male/female barbed connectors available in this thread so I could make short connecting hoses using surgical tubing? Or would I have to make those, too?
I intend to make male connections for my engines and maybe even a manifold with 5 or 6 connections on it to run all my engines at once. Any ideas/input/criticisms welcome. Tell me what you do. If Iím way out in left field, donít be afraid to bring me to my senses. Who knows, I may be exhibiting my bunch at Cabin Fever someday!
Chuck

Offline mklotz

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Re: Model Engine air system
« Reply #1 on: June 07, 2013, 12:47:09 AM »
Quote
I know there are taps for this thread widely available, and dies not so widely available.

Huh?

http://www.use-enco.com/CGI/INSRIT?PMAKA=891-4816&PMPXNO=3904720&PARTPG=INLMK32

Quote
Is this thread tapered?

That's what the 'T' stands for; NPT = National Pipe Taper

NPT fittings seem like overkill to me for small air engines.  My "heptapus" manifold uses the small valves available for refrigerator ice cube makers, barbed fittings and silicone aquarium tubing to connect to smooth fittings on the engines (could be barbed but I don't bother).  The heptapus has a standard quick air connect to attach it to any compressor to hand.  It includes a regulator and a water trap.
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Offline Tin Falcon

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Re: Model Engine air system
« Reply #2 on: June 07, 2013, 01:30:27 AM »
Her is what I typical do :  Most show venues have 1/4 NPT female taps with a valve.  I carry a tee in case I can only access one tap. I thread a hose with a quick disconnect into the tap i connect the other end to a male qd from Harbor freight . the same type of connector seen on an air tool. this splits to two regulators. each regulator feeds an aquarium manifold.



Look here :http://www.homemodelenginemachinist.com/f14/engine-displays-758/


Tin
« Last Edit: June 07, 2013, 01:33:50 AM by Tin Falcon »

Offline chucketn

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Re: Model Engine air system
« Reply #3 on: June 07, 2013, 01:59:09 AM »
Marv, I'm all ears! Care to expound on the "heptapus manifold"?

Tin, was that setup under the table at Cabin Fever this year? I didn't see it.

Chuck

Offline Tin Falcon

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Re: Model Engine air system
« Reply #4 on: June 07, 2013, 11:31:38 AM »
Chuck that setup was on the table at cf. It is the rear view of one of my show boxes . I actualy have 5 regulators running and an aquarium manifold on 4 of them.

http://www.aquacave.com/Multi-Outlet-CHROME-Air-Manifold-by-Sunlight-Supply-P2226.aspx?gclid=CNnuvvjd0bcCFYuZ4AodMjEASg

tin

Offline Tin Falcon

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Re: Model Engine air system
« Reply #5 on: June 07, 2013, 11:50:37 AM »



I should add a note here. This drawing shows a 4-40 thread. I have made similar connectors in 10 -32 and 1/4 20 as well. and I use an o ring seal  to prevent leaks . also a thin slice of silicone rubber hose  can be used if you have no O-ring of the correct size.

I made a block manifold years ago and it does work. but for  the money the aquarium manifolds are nice and if you want something nicer you can get stainless steel ones as well.
Also guys have used PVC pipe as a combination  air reservoir and manifold. this is fine for low pressure less than 15 psi . do not use PVC for  line air it can explode.
Tin
« Last Edit: June 08, 2013, 01:12:16 PM by Tin Falcon »

Offline b.lindsey

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Re: Model Engine air system
« Reply #6 on: June 07, 2013, 12:22:53 PM »
Note to self....as far as compressed air supply...try not to be downstream of Tin at next year's CF   :lolb: :lolb:  Seriously though....nice set-up Tin!!

Bill

Offline chucketn

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Re: Model Engine air system
« Reply #7 on: June 08, 2013, 12:04:14 AM »
Maybe I didn't make myself clear. I've never heard of a "heptapus manifold". Marv, you are always willing to explain complex math theory, what is a "heptapus manifold"? :stickpoke: :headscratch: :shrug:

Chuck

Offline mklotz

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Re: Model Engine air system
« Reply #8 on: June 08, 2013, 12:27:02 AM »
Maybe I didn't make myself clear. I've never heard of a "heptapus manifold". Marv, you are always willing to explain complex math theory, what is a "heptapus manifold"? :stickpoke: :headscratch: :shrug:

LOL.  No "complex math theory" here, Chuck.  It's all very simple...

Originally my manifold was made of a hexagonal block of aluminum with a valved outlet in each face.  When one of my friends saw it with six green aquarium hoses emerging from it he remarked that it looked like an octopus.  I corrected him and from then on it became the hexapus manifold.  Later I added one more line emerging from the top of the block and thus the heptapus manifold was born.
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Offline chucketn

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Re: Model Engine air system
« Reply #9 on: June 08, 2013, 01:50:40 AM »
Hey Marv, how about a picture of "heptapus", and the ice maker valve? Is the valve the "after market" type in the home center type stores?
I'm all for cheap and cheerful, but I want something that will be easy to use and adapt to any style engine that can be powered by compressed air.

Chuck

Offline mklotz

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Re: Model Engine air system
« Reply #10 on: June 08, 2013, 10:37:24 PM »
OK, Chuck, just for you...  Here's a picture of the heptapus manifold.  Air is admitted from the quick-connect fitting on the right (in operation the heptapus stands vertically), passes through a water trap and into the regulator, then into the hexagonal aluminum piece which contains all the valves to distribute air to the engines via the green silicone aquarium tubing (recommended).



And here is a close-up of the manifold showing the individual valves. 



I seem to remember the clerk telling me that the valves were used in supplying water to refrigerator ice makers but don't hold me to that;  I'm an old man and memory is the second thing to go.
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Offline Maryak

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Re: Model Engine air system
« Reply #11 on: June 08, 2013, 11:45:25 PM »
Now I've seen it.................I reckon it's an Octopus with a regulated leg  :LittleDevil:

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline mike 44

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Re: Model Engine air system
« Reply #12 on: June 18, 2013, 11:15:03 PM »
...........

Chuck, the 1/8/27 thread is tapered. You should be able to buy the tap or die at any hardware store.
Actually a pipe taper is not needed. I use a 4/40 fitting and it works fine. I turn the brass stock to a barb fitting for either 1/4" or 3/8" clear plastic hose, the other end is a 4/40 thread. The barbed end also has a small hose clamp.Very simple to make. You might be able to skip the barb if you heat the tubing with hot water and slide it on to cool.Then add a hose clamp.I did just this a few times until a tube popped off under too much pressure.
mike