What I assumed was brass, not sure now.

[hunter27]

Hi.
In my stash of spare stock I had a 75mm diameter chunk bass, I don't remember where it came from.
I bored out a inch and a half hole in it and parted off a 1/2" thick piece. It was not like any brass I have cut before making mainly fluffy swarf not little sharp chips. Parting it off was a challenge but I got there in the end with a really slow feed rate. A couple of times the tip dug in and I had to run an hacksaw blade in the groove to clear the divot which seemed really hard.
Then I put it in my new to me mill and really struggled to drill a 4mm and then a 5mm hole through it, I changed the drill bits twice but that didn't help.
I then had to tap a 4mm thread in one of the holes so I used a first tap and lots of lube and eventually got through but the thread was really tight so I then used a second tap gently with cutting oil back and forth but you guessed it, the tap snapped in. I have changed the design now still using the part.
I know there are lots of different brass types and was curious to know if anyone could say what it is?

Some bits of swarf from the scrap bin.


?

 

[MattF]

Possibly some form of bronze.

 

[Hood]

Yes, looks a bit like phosphor bronze.

 

[hunter27]

I assumed phosphor bronze was relatively soft? The last job I did was on a chunk of 304 stainless steel and that was easier to work with.

 

[Hood]

I assumed phosphor bronze was relatively soft? The last job I did was on a chunk of 304 stainless steel and that was easier to work with.

Nope, quite hard stuff, I was annoyed last week as I snapped a nice 10mm carbide cutter by trying to feed a bit too fast

 

[brightspark]

i had to drill out a piece 10 inch long x25 mm in the lathe it didnt like it and was bloody hard. had to let it cool down quite a bit as it was biting

 

[Misterg]

Could be aluminum bronze of some sort, too.

 

[Screwdriver]

Yeah, there is an entire family of bronze alloys and they're all vastly different while appearing to look quite similar.

I wonder how often some fabulously exotic and expensive alloy stock ends up dirty and dusty in the back of sheds up and down the country...

 

[Keith 66]

Looks like alumininium bronze, My father in law got given a load of it. It is a bastard to machine.

 

[BrokenBiker]

I tried machining phosphor bronze in my little China lathe and it wouldn't have it at all...horrible stuff if you haven't got the right tooling for it

 

[Hood]

I was machining some phosphor bronze today and the swarf looks like this.

 

[hunter27]

I was machining some phosphor bronze today and the swarf looks like this.

View attachment 497288

Just like the swarf I got.

 

[Screwdriver]

I hope you're not making a doorstop!

Lump of Phosphor Bronze that size could cost a chunk of change. Course, you'd have to know what grade it is....

 

[hunter27]

I hope you're not making a doorstop!

Lump of Phosphor Bronze that size could cost a chunk of change. Course, you'd have to know what grade it is....

Made a collar from it to hold a DTI on the milling machines spindle. Was doing a mod to it today having to drill and tap a couple more holes in it. It is really gummy stuff, (seems to grip the drill bit and taps) requiring a very sharp drill bit and the taps are almost as hard to wind out as in.

 

[Hood]

Tapping is quite challenging, much harder to do than steel/stainless etc. The part I made had an M16 thread and initially I was power tapping it, ended up having to just hand tap and use a taper tap to get it done. WD40 or similar helps a lot and in my experience is better than using a cutting compound.

 

[Screwdriver]

Slight digression. We've all seen the adverts for "Anchorlube" a water soluble cutting paste. Ideal if you're welding and don't want any oil contamination but also much easier to clean up, good for the hands etc.

I really rate it, the difference is phenomenal especially with drilling and tapping. I could be spinning away like an idiot trying to drill a hole in even some mild steel (all my drill bits are as blunt as a Yorkshireman). Tiny dab of Anchorlube, you can pile on the pressure, bit stays cool and it just cuts...

Dunno how it goes with brass but I thought worth a mention if anyone hasn't tried this stuff.

 

[MattF]

WD40 or similar helps a lot and in my experience is better than using a cutting compound.

That & GT85 both seem to work well on brass. WD40 has the edge over the other.