gas jets

[John Rudd]

A number 8 jet has a hole smaller than a number 80 drill I'm told,so who knows how the small holes are machined into a gas jet?

 

[doc1955]

I've seen drills down to #97 and I know Travers has drills down to a .10 mm which is a .004 dia.

 

[GailInNM]

For a Number 8 gas jet:
Gas jet thread 1BA, hole size 0.25 mm or #87 drill bit.

For reference a Number 5 has a hole size of 0.20 mm or #92 drill bit.

To drill, everything must be lined up very close and the drill run at high speed. I made a few and ran the drill at 17000 RPM. Keep the depth of the jet hole down to about 0.010 to 0.015 max inch so you don't have to drill very far.

You can get center drills down to 0.010 tip diameter.
There are lots of carbide circuit board drills with 1/8 inch shank in these size ranges on e-bay. Search for micro drills.

Gail in NM

 

[John Rudd]

Thanks guys... :bow: :bow:

I was beginning to wonder...

Didnt realise there were drills smaller than a number 80....

 

[shred]

A while ago I ran across a Colin Binnie article on making the little drills and using them to drill gas jets, but I seem to have lost the link.

Another alternative is to take something like a #80 hole and swage it down smaller around a bit of thin wire, then pull out the wire.

 

[cfellows]

A while ago I ran across a Colin Binnie article on making the little drills and using them to drill gas jets, but I seem to have lost the link.

Another alternative is to take something like a #80 hole and swage it down smaller around a bit of thin wire, then pull out the wire.

I think I'd need a magic wand to do something like that, Shred. :big:

 

[mklotz]

I can vaguely remember reading somewhere about making extremely small holes by using a needle to punch holes in very thin sheet metal. (The application may have been pinhole cameras but it's all very hazy.) The hole size was controlled by the depth of penetration of the needle. I'm wondering if the idea could be adapted to this application.

 

[shred]

I can vaguely remember reading somewhere about making extremely small holes by using a needle to punch holes in very thin sheet metal. (The application may have been pinhole cameras but it's all very hazy.) The hole size was controlled by the depth of penetration of the needle. I'm wondering if the idea could be adapted to this application.

That's what the cheap pencil-torches do I think-- the "Jet" is just a piece of punched foil.

 

[shred]

I think I'd need a magic wand to do something like that, Shred. :big:

Here's the relevant bit. I'm not sure it's a recommended way, but it's an option.

 

[IanN]

Hi,

This thread seems to be suggesting using a drilling head to make the jet hole - it is much easier to put the jet in the lathe and rotate the work rather than rotate the drill.

To drill, everything must be lined up very close and the drill run at high speed. I made a few and ran the drill at 17000 RPM. Keep the depth of the jet hole down to about 0.010 to 0.015 max inch so you don't have to drill very far.

If the work is rotated, when the drill starts to wander it will tend to pull itself back towards the centre of rotation. This allows the hole to be drilled holding the bit in a pin vice. There is no need to use high spindle speeds or to use a precision drilling head. Watchmakers have been using the technique for several hundred years in very simple bow powered "turns"

It is not sensible to use a conventional centre drill at such small sizes - it is better to "catch" the centre using a graver.

The four video clips below show how I drill small holes in the lathe (the first clip is about the graver - not of much interest if you are already familiar with the tool):

The graver:
[ame=http://www.youtube.com/watch?v=lZ7PP4KgzmU]http://www.youtube.com/watch?v=lZ7PP4KgzmU[/ame]

Catching the centre:
[ame=http://www.youtube.com/watch?v=f8IDhos0Qtw]http://www.youtube.com/watch?v=f8IDhos0Qtw[/ame]

Drilling the hole:
[ame=http://www.youtube.com/watch?v=maUtJ2UBuMs]http://www.youtube.com/watch?v=maUtJ2UBuMs[/ame]

The finished hole:
[ame=http://www.youtube.com/watch?v=hiXwU0qn9s0]http://www.youtube.com/watch?v=hiXwU0qn9s0[/ame]

Ian.

 

[shred]

Nice vids. How small a hole can you get to with a hand-held pin vise? Drilling them in the lathe is the way Binnie used to do them as well.

 

[GailInNM]

Very nice Ian. Thank you for the informative post.
I will give that a try the next time around.
Gail in NM