Oilite is a porous bronze, impregnated with oil. It tends to be used at the size as purchased. Machining can be difficult as it is all too easy to close the pores, thereby rendering the bearing properties useless

SAE660 is a leaded bronze, easy to machine and fine for bearings. LG2 is a leaded gunmetal bronze, ie, contains zinc as well as tin as one of the alloying constituents. I don't know what RH7 means. By far and away the most common bronze is PB102; that will be fine for bushes and bearings.

Andrew

Best to restrict your use of phosphor bronze PB 102 to boiler fittings rather than for making bearings. The leaded bronzes SAE660 and gunmetal LG2 are so much easier to machine and are intended as bearing materials. Oilite is also good, provided the shaft fits without the need to adjust the bore of the oilite bush.

Hi Duncan

You probably already know that the classic solution to machine PB102 without tears is to use a top quality drill (I hesitate to say, but not FE), coolant and take it easy. I did use some for a fishing reel that I made and had no problems (used 4 facet TIN coated Dormer drills).

But perhaps using Calphos 90 would be a good solution. Reasonable properties and excellent to machine, although a bit expensive. I got some from Noggin End a couple of years ago; not a great selection of sizes, but was OK for my needs and machined perfectly.

Cheers – Will

By coincidence, I have just machined a couple of traction engine cylinders from PB102, simply because I found a piece that was just right in my scrap box. I drilled it through 3/4" without any problems, then bored to near size followed by reaming. The reamer has seen better days but with a touch-up with a diamond file worked well enough. I shall hone the bores but not until the cylinders have been silver soldered to the stands that hold them to the boiler and the valve chest.

I thought that the metal was being hard to work but then realised that the reamer was starting to cut the inside of the morse taper in the lathe spindle! No serious harm done fortunately but just goes to show that you need to keep your wits about you at all times.

Brian

+1

I've not had any problems using Dormer A002 drills, except for snatching on breakthrough as per most bronzes and brasses. I'm slowly building up a set of slow helix drills and these seem to work fine on PB102. On the lathe I always use flood coolant when drilling.

On t'other hand reaming can be a bit of an issue. Bronze and brass seem to sometimes close up slightly leaving the hole undersize. It's only a few tenths at most, and not an issue if using cold drawn stock as the shaft. But it's a PITA if you've ground a special shaft only to find it too tight.

Andrew