anyone know their brass?

[anonymous-user]

I've been machining some brass things and found that one type of brass bar I have is quite a deep gold and machines really badly with long springy spiral shavings and a tendency to vibrate a lot , whereas another brass bar machines really well and gives off loads of tiny shavings instead and has an almost white finish when machined.

Both are old and I've no idea where I got them from.

So does anyone know their brass grades and what types I might have there so I can avoid buying more of the nasty gold one?

[fourfoldroot]

It could be bronze or phosphor bronze. The way you describe it is most likely phosphor bronze. It’s expensive compared to brass. Good for hard wearing bearings.

[Simpo Two]

I encountered a similar problem when trying to turn small brass parts for a model boat.

The brass rod from eBay was very easy to turn, but the brass sheet from a model shop was as hard as steel and a real bh. Enquiring here it seemed the difference was that sheet is rolled which makes it harder, so you have to anneal it (heat to read heat) to put the molecules back. I tried it and it did make a difference.

On top of that of course brass is an alloy so I'm sure there are hundreds of different kinds of brass.

[robemcdonald]

The good stuff might be nickel aluminium bronze. Notoriously difficult to machine if you don’t know it.
You can put a chip breaker on your tool to stop the long ribbons of swarf.

[anonymous-user]

OK thanks, now I'm even more confused

I really like the one that turns white when machined and leaves just lots of tiny pieces, the other more gold-coloured one was such a pig to use that I gave up with it, so I was hoping the whiter one was an easily identifiable grade that I could order again.

I'm not making anything that requires strength or anything like that, just some little doodads for fun.

Edited by anonymous-user on Saturday 16th May 18:00

[Simpo Two]

JimSuperSix said:

one type of brass bar I have is quite a deep gold and machines really badly with long springy spiral shavings and a tendency to vibrate a lot...

Obvious question but are you going at it too fast? And are your cutting tools in good order and the right clearance angle etc?

[Big Al.]

The one that turns swarf with a spiral, is a free machining brass that has a higher % of lead in the mix, it's primarily used for tube and drawing manufacture.

The other has less lead and will produce a spray of swarf. This is generally used for casting, producing solid forms round/hex/square bars etc.

You need to look up brass compositions for usage comparisons.

https://www.thoughtco.com/composition-of-common-br...

HTH.

[Big Al.]

Simpo Two said:

Obvious question but are you going at it too fast? And are your cutting tools in good order and the right clearance angle etc?

Turning tools (HSS) for the lower lead content need to have a negative top rake, free cutting brass around a 5 degree. Speed is primarily dependant on dia of part being machined.

This may help

https://littlemachineshop.com/reference/cuttingspe...

[anonymous-user]

Big Al. said:

The one that turns swarf with a spiral, is a free machining brass that has a higher % of lead in the mix, it's primarily used for tube and drawing manufacture.

The other has less lead and will produce a spray of swarf. This is generally used for casting, producing solid forms round/hex/square bars etc.

You need to look up brass compositions for usage comparisons.

https://www.thoughtco.com/composition-of-common-br...

HTH.

OK thanks, looks like a need the lower lead content variety , will have a read of that link cheers.