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[bigegg]

I have a new project 

For which I need some accurately sized holes of around the 1mm size

I've been reading up on watch bushings, which lead me to mig welding tips and then to gas(burner) jets -
which appear to be some sort of industry standard size with a 1BA external thread.
They are sized by number but I can't find a chart which lists hole size to jet number

Does anyone know what size jet corresponds to 1mm hole diameter, and preferably all the jet sizes between 0.9mm and 1.1mm ?

Thanks

[redelitev6]

  come on don't be a tease, what's it for? the mind boggles !

[bigegg]

Nothing interesting, I'm afraid...

It's for a gas burner for my foundry.

Exact hole size depends on the size of the kiln/foundry interior, the diameter of the burner tube, the length of the tube, and apparently what star sign it's made under...

Usual method is to start with a 0.9mm(ish) drill bit, and work outwards until it works.

I can't get micro drill bits locally, and I'd have to buy a pin drill, which means £20+ and a week's wait for delivery.

I can get gas jets locally, and I can return the ones that don't work - so outlay is only about 4 quid

[redelitev6]

Nothing interesting, I'm afraid...

It's for a gas burner for my foundry.

Exact hole size depends on the size of the kiln/foundry interior, the diameter of the burner tube, the length of the tube, and apparently what star sign it's made under...

Usual method is to start with a 0.9mm(ish) drill bit, and work outwards until it works.

I can't get micro drill bits locally, and I'd have to buy a pin drill, which means £20+ and a week's wait for delivery.

I can get gas jets locally, and I can return the ones that don't work - so outlay is only about 4 quid

A good stockist like wolseley should be able to help you out, if they can't i'm sure they could point you in the right direction

[bigegg]

Trouble is, (and this might have changed in the last couple of years),
if you walk into a plumber's merchant and ask for gas fittings.
If you don't appear to know what you're doing, they won't sell em to you

 

I have my british gas hi-vis (charity shop, 50p), so look the part, but if I start asking questions...

[redelitev6]

Trouble is, (and this might have changed in the last couple of years),
if you walk into a plumber's merchant and ask for gas fittings.
If you don't appear to know what you're doing, they won't sell em to you

 

I have my british gas hi-vis (charity shop, 50p), so look the part, but if I start asking questions...

The ones i have dealt with have always been helpful to me and i'm a daft joiner by trade ! always worth a visit to them

[bigegg]

Maybe it was just the one clerk, at that particular factors, and just after the new regs came in...
I wouldn't mind, but I was only after iron gas pipe to make a panel saw slide 

[Andy H]

I wouldn't be at all surprised if the jets are 'Amal' (as manufactured by the British Amalgamated Carburetor Company since about 1350) (I made that last bit up)

Amal parts are now made by Burlen Fuel systems. Manufacturing parts for vintage motorbikes is only a small part of their business today. They seem to make most of their money now selling gas jets

Amalgamated Carburetors

Burlen Fuel Systems (the link to the Amal part of their website isn't working today, seems to be something wrong with their Microsoft webserver).

Jet Brochure pg1 & 2 - AMAL"Amal jets accurately control the rate and direction of discharge. at stated pressures. primarily of gases such as natural gas. methane. sludge gas. coal gases."

[bigegg]

Thanks for the links!
As far as I can tell, the gas jets were originally made by calor, and subsequetly adapted as a standard.
The only ones I can find listed by mm hole size are:

Number 3 which has a 0.15mm dia jet bore

Number 5 which has a 0.2mm dia jet bore

Number 8 which has a 0.25mm dia jet bore

Number 12 which has a 0.3mm dia jet bore

Number 16 which has a 0.35mm dia jet bore

I know they go to at least size 91, which extrapolating from the above is possibly in the range 2.5mm-3mm
but I need accurate 

[STMO123]

I thought "how hard can this be?" and had a quick google. Didn't take me long to get a headache. It's a science all on it's own

[bigegg]

I've been at it for 5 hours 
and my google-fu is *strong* - I used to do it for a living

[STMO123]

I find that the best way to work something like this out is to say

"I BET EVEN MARK DTM COULDN'T WORK THIS ONE OUT!"

And he gets all uppity like and comes back with answer