Parting 1 1/2 phosphor Bronze

Well done Martin, glad you have confirmed it, REALLY sharp HSS tool.

Mike, slitting saw, same answer, the teeth will have to be freshly honed, or use a new saw blade.

Well, someone is welcome to correct me if they'd like, but I think that ain't phozzy-bronze, which is a pretty pink colour because the addition of phosphorous reduces the oxygen content and leaves the bulk material near the colour of fresh copper.

It's not aluminium bronze, which is a pig to machine cos' it work hardens and grabs. It is a much lighter yellow.

That sexy sun tanned golden colour is a different relative of the bronze family, with all the potential delights of work-hardening characteristics.

Any takers?

Simon

I have a number of lengths of different diameter bronze bar, some just bronze, some leaded, some phosphorbronze, etc. They come in all sorts of colours from near brass to near copper. I consider all of them easy to machine except for the silvery light yellow bar. (Some years ago I posted a thread about aluminium bronze, the obvious questions and later my experiences).

JA

I've bought drawn, as opposed to cast, phosphor-bronze. It seems to have a more coppery colour than the cast material. Another feature is that it can be considerably more difficult to machine, especially noticeable when drilling. The drawing process leaves high internal stresses in the material. During machineing these stresses bring about minor distortion causing the tool to rub heavily.

Maybe the OP's material was a bit of this stuff.

A rear toolholder for parting blades can hold any size of blade because the edge is upsidedown. You could use an industrial 32mm blade on a Myford which could not fit in the ordinary toolpost. The advantage is that the chips fall away from the work more easily assisted by gravity.

Nothing to do with parting PB but maybe as of interest, I have just parted this last week a 5" noggin of mild steel in a Colchester Student to make the 90T bull-wheel for the Parkes gear hob backing off device with no problem at all. No digging-in, no breakages and a tool protruding 2.5" from the tool holder, although I let it out in stages. This is not the first time I have done this as I have parted various large noggins previously to make back-plates for the Myford. The tool holder is the J&S type that holds an Eclipse type of blade, used straight off the grinding wheel, and held in an home-made rear tool-post as near a copy of the OEM accessory as I could manage.

Can't speak for PB but my method of parting these large noggins, and for all other parting in steel, is moderate speed (increased as the diameter decreases) and lashings of coolant pumped on, not dabbed or squirted, and a good cut that should not be interrupted once it has started. Aim for a nice 'hiss' and a ribbon or ringlets of swarf. I have used the power cross-feed before but not on this last occasion. The noggin was held as tight as possible in the 4-jaw independent chuck as I believe, or have been told at least, that four-jaws hold work more securely than 3-jaw scroll chucks and if I ever see a hacksaw near a lathe, I reach for my revolver, LOL!

Roger, Norm thanks for the comments. It was a brand new slitting saw, 0,75 not 0,5 as I originally mis-typed! Perhaps it was just down to poor quality (although I tend to buy stuff from reputable suppliers normally). Will just be a bit more cautious if I have to try this again? Regards