3/8-28 ended airline hose : chuck it or use it?

[student123]

I've bought an (airbrush) compressor. Came with a hose one end 1/4" BSP swivel nut to connect to the compressor. The invoice says the other end is a 3/8-28 female connector. Suppliers website doesnt have much more detail:

http://www.everythingairbrush.com/c...com/&WD=ab-21&PN=Hoses.html#aAB_2d21#aAB_2d21

part code is the AB-21

I (think I) need to connect an airline hose from the compressor to my 'allegedly-EZ-build' steam engine. On the engine the input tube is approx 3mm diameter.
From what I can see on the web the small hose connector seems to have an obscure thread. (UNF? UNC ? NEF ? UNEF?)
http://brassgoggles.co.uk/forum/index.php?topic=20511.0

Better to look for a 3/8-28 die to thread the input tube, or bin the hose & find one with a simple-dimple end connector thread (eg 3mm) where I already have the threading dies?

I'll probably do the latter, but just wondered if anyone else has wrested with similar problems, has any advice etc.

 

[JimM]

Haven't you got that the wrong way round. The 3/8 end of the hose screws to the compressor and the other is the standard 1/4" BSP. Plenty of 1/4" adapters available or you could make your own to step down to whatever size airline you need to connect to the engine

Cheers

Jim

 

[Stan]

I don't know anything about air brushes so I did a search on air brush hoses. It seems that every airbrush maker uses proprietary fittings and you have to buy adapters to interchange between hoses and guns. The search brought up all the different combinations of male and female ends to adapt the various hoses to the various guns.

 

[Maryak]

S123,

Go to a hydraulic hose fitting shop they have connectors up down and sideways to match anything to anything, (well at least they do in Oz because we have such a hodge podge of equipment).

Best Regards
Bob

 

[bentprop]

3/8 seems a bit big for an airbrush.Just cut off the 3/8 connector and fit whatever you want.Take the whole shebang to an air fittings supplier,and they'll probably fit it for nix if they're not too busy.My Paasche airbrush has some weird threaded fitting,but Paasche has spare fittings to suit.

 

[student123]

Jim,

Its 1/4" at the compressor, I checked with calipers & the "manual" (more like a leaflet equivalent 2 a4 pages, e.g. no mention of how to regulate the pressure) does have that as the output size.

All,
Feeling a bit annoyed - on the phone I let the supplier trade me up (on a reference to another model engineers experience) from the cheaper AS06 model with built in regulator & gauge to the next model up - he didnt tell me the next model up it was minus regulator & gauge.
Now I find the hose has obscure threads. Grrr...

(On the guys credit side I should say he stopped me buying an on-demand type compressor, saying it was unsuitable)

No hydraulic hose fitting shop near me as I can find, but:

If I was going to ditch the obscure threaded end, instead I'll find the nearest metric equivalent & make an adaptor using my metric
dies. With a bit of cross threading , some glue & heatshrink I should sort it. See how it goes...

Thanks for all the responses.

Mike

 

[JimM]

Jim,

Its 1/4" at the compressor, I checked with calipers & the "manual" (more like a leaflet equivalent 2 a4 pages, e.g. no mention of how to regulate the pressure) does have that as the output size.

My bad, mis-read the hose spec on the website, however looking at it again like others have suggested I'm pretty sure the 3/8" is a typo on the invoice. Everything else on the everythingairbrush site is 1/8" BSP which would also be correct for a 28tpi thread - suppose an easy way to answer the question is if the fitting is smaller or larger than the 1/4" at the compresor end. Assuming it is 1/8" then buying or making an adapter shouldn't be an issue, any ot hese any good

http://tinyurl.com/32ca2rc

Cheers

Jim

 

[student123]

Jim,

Thanks, sorry for delay in response. Measureing the diam of the airbrush end , it seems also 1/4", but with a smaller external locking nut (approx 1/3" int diameter). I'll give the supplier a call.

Mike

 

[Stan]

Your post caused me to get out the Machinery Handbook to look up BSP. It seems that BSP is British Standard Pipe and is used to refer to both tapered and straight pipe. In North America we use NPT or NPS which is National Pipe Tapered or National Pipe straight.

Are the fittings that you are working with tapered or straight? If straight, what kind of seal are you using?

 

[student123]

Are the fittings that you are working with tapered or straight? If straight, what kind of seal are you using?

Stan,
Sorry, I can't tell if tapered or straight - the external locking nuts cover the inner airline tube. The inner tube has a black o-ring round it.

If I cant get info from the suppiler , I'll cut an internal thread & attach some brass tubing of a straightforward thread size

Mike


Mike