drilling brass?

[Robin Hewitt]

Is this old brass?

I used to have terrible trouble with brass and it's wonderful tendency to snatch, but not for many years, thought maybe they'd improved the formula and the world had standardised on CZ something or other.

To drill it you mustn't have any slack in the system, it mustn't be able to pull the bit forwards and dig in. That was it's ambition in life.

Lube might help, you could soften it up, possible not a good idea if it's a bearing face. Treat as per copper, apply soap, heat 'til it goes black. Quench or air cool makes no difference, only way to harden brass is to wait a few years.

Edit: Forgot, it does work harden

Um, err, good luck :whistling:

[irving2008]

old as in 100 years give or take 5 - the lathe was made in 1914!

i've ordered some stubbies....

[Peter Griffin]

Irving

The cutting edge of the drill needs to have a negative cutting angle. Grind a flat on the cutting edge. This way the drill can't snatch.

[irving2008]

Sorry Peter you'll have to explain that more

[Robin Hewitt]

The cutting edge of the drill needs to have a negative cutting angle. Grind a flat on the cutting edge. This way the drill can't snatch.

That could work. But obviously we aren't explaining it very well.

The problem is probably 'engineering speak'.

Brass 'snatches' where other metals 'dig in'. It has a word all of it's own, probably because it does it so well.

If Irving, thinks 'dig in' rather than 'snatch' then the 90 degree, or more, rake angle might make more sense.