NG10 blow gun Thread- any idea?

This topic has 11 replies, 6 voices, and was last updated 25 July 2015 at 23:15 by Alan Hopwood.

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5 July 2015 at 22:02 #195878
Ian Welford
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@ianwelford58739
Looking at making an extension tube for an NG10 blow gun- common enough item and I assumed it would be 1/4 BSP thread ( as the air line fitting which goes into it is ) but no.

The closest match I can find is M10 fine ie 1mm pitch but the thread profile is wrong according to my M&W thread gauges anyway.

I tried all the whit and even UNF but nothing truly matches!

Anyone got any clues on this?

Thanks Ian
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5 July 2015 at 22:02 #17766
Ian Welford
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@ianwelford58739
5 July 2015 at 22:18 #195881
Frances IoM
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@francesiom58905
is it BSPP 1/8th – found the same on a Miller 2000 small compressor intended for air brush use OD of male is 10.3 mm with 28 TPI – I now need to make a converter to 1/4 BSP

maybe some one could explain these strange pipe sizing threads ?
5 July 2015 at 22:48 #195883
Capstan Speaking
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@capstanspeaking95294
If it's not 1/8 BSP then it's probably American NPT.
5 July 2015 at 22:56 #195884
Frances IoM
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@francesiom58905
the American NPT 1/8 is 27 tpi tho with same pipe OD – now I’m worried as not sure I could easily note the difference over the small length of thread available – does anyone own one of these old compressors? – being British made I assume would be BS
6 July 2015 at 06:39 #195897
Capstan Speaking
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@capstanspeaking95294
NPT is not unheard of in British pipework. Now I could roll a grenade in the room by mentioning Enots standard fittings too. They even have their own spanner sizes.
6 July 2015 at 21:27 #195994
Frances IoM
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@francesiom58905
you may have determined thread by now but my cheapo Toolstation air blow gun with ‘long reach’ uses the same thread between body and long reach extension tube that my old Miller compressor has, thus would appear to be 1/8 BSP – found Axminster to a converter to 1/4 BSP for little more than the cost of the brass I planned to make one with

Edited By Frances IoM on 06/07/2015 21:28:22
6 July 2015 at 21:57 #195998
Ian Welford
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@ianwelford58739
Visually it looks very close to BSP (compared to a tap) but the 1/4 bsp die nut (Presto) is a no go!

across crests of threat its 9.8mm, I'll have a look at American NPT with the thread gauges , as that's very close. to 1mm pitch but only 5 threads to measure over!

All this to make an adaptor to fit a fine nozzle for a specific wood turning job.

Many thanks for all the suggestions folks
7 July 2015 at 01:20 #196014
Jeff Dayman
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@jeffdayman43397
Weld or epoxy glue in a BSPP or BSPT or NPT female adapter and the plumbing possibilities are endless. Not worth hours of thread detective agency work / head scratching / multiple beers (well the beer would be worthwhile, I grant you…)

Good luck, JD
7 July 2015 at 10:00 #196031
Clive Foster
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@clivefoster55965
Ian

Had similar imported air connector mystery thread recently. Turned out to be Admiralty Fine which really is one for the obscure list. Although it does have a certain logic.

Whitworth (55&deg form and Sizes by outside diameter are :-

Under 1/2 inch – 24 tpi – 0.0267 deep.

1/2 and under 3/4 inch – 20 tpi – 0.0320 deep.

3/4 and under 1 inch – 14 tpi – 0.0457 deep.

1 and under 2 inch – 12 tpi – 0.0533 deep.

2 and under 4 inch – 8 tpi – 0.0800 deep.

4 inches and above – 6 tpi – 01067 deep.

There are no nominal sizes. You can put the thread on anything within the specified size range which can be very handy when struggling to fit a thread in, especially concentric ones, and monumentally confusing for folk not in the know.

I'd be unsurprised to discover 60° metric thread forms applied to imperial sized stock.

Clive.
25 July 2015 at 22:35 #197977
Ian Welford
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@ianwelford58739
Well, when in doubt ask a friend to have a shufti at it!

Thanks Alan!

Very, very close is 3/8 x 26tpi Brass! This fits extremely well. I guess they used it because the casting is alloy ( sort of Merzac type metal not pure aluminium for sure.

Have now made my nozzles and am off to have a play.

Thanks one and all for the input.

JD – I know I could just lash something up and make it "universal fitting" with a BSP fitting but you know how some things get under your skin and you want to know ……? Mind you if I'd had to buy a die for it I might have been less sanguine about it.

Regards Ian
25 July 2015 at 23:15 #197979
Alan Hopwood
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@alanhopwood63369
Ian, Glad that the 3/8 British Standard Brass thread proved correct. I'm also please that you had a die (must try to remember that for the future). I suspect that the material, which you say is not Ali, will be Mazak which is a zinc based die casting alloy.

S&F,

Alan.
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