Brass v.s. Bronze?

[DianneB]

I am preparing to build a VanBrocklin pump from Bill S. plans.

I have a large piece of bronze surplus to my needs but no brass.

Is there any reason to buy brass or can bronze be substituted in making the brass parts?

(I have very little experience machining small parts!)

[Harold_V]

It would be my opinion that substituting bronze for brass would be quite acceptable, as bronze has qualities that are generally not found in brass.

The chief difference between brass and bronze is the alloying agent. Brass is typically made with zinc, while bronze is typically made with tin.

Unfortunately, the line fades, and the above isn't necessarily true in all instances.

Be aware that some of the bronze alloys are extremely difficult to machine. Some are more difficult than tough steel alloys (I offer manganese bronze as an example).

Phosphor bronze is difficult to machine, while leaded phosphor bronze is amongst the nicest of all alloys to machine. Armed with this thought, it should be apparent that the alloy in question would be considered before making a decision.

H

[Wolfgang]

I'd cut a small piece and do a little test machining to see how easy or difficult it is to get a good finish in reamed or bored holes; how easy to drill and tap the smallest screw sizes you will encounter, etc. w

[pete]

Fwiw and not information gained through actual long term testing. And it would also depend on the exact alloy as Harold mentioned of course. But from my reading Dianne the general recommendations when using bronze is to use hardened shafts for anything rotating within a bronze bearing. For something like a cylinder end cap with the piston rod surrounded by the packing gland it wouldn't matter. I've got a whole lot of bronze here salvaged from various mining parts and some machines like it's much harder than mild steel. It's possibly Aluminum Bronze, or maybe Harolds Phosphor Bronze? Given the tool edge life while machining it with HSS then my best guess is that hardened shafting would be a good idea if it was being used as a bearing material.

[DianneB]

The bronze I bought 20 or more years ago for a completely different use with potable water purification, a 4" diameter bar of which I have about 8" left.

I don't remember the alloy but it machines beautifully on the lathe. I will test it with drilling & tapping small holes and if handles that easily, I will go ahead a use it.

Thanks gang!

[stephenc]

I tend to look at things from a cheapskates point of view , if the actual material used didn't matter I'd pick the brass every time ... bronze alloys are pretty darn pricey .

On the other hand , if looks are important I'd pick the bronze simply because I like it's color quite a bit more .

[Harold_V]

It's possibly Aluminum Bronze, or maybe Harolds Phosphor Bronze?

It would be difficult to confuse those two. Aluminum bronze has a pale yellow color, while phosphor bronze looks very much like copper. Even leaded, it's quite red.

Aluminum bronze is not fun to machine, either.

H

[Harold_V]

On the other hand , if looks are important I'd pick the bronze simply because I like it's color quite a bit more .

Depends on the bronze. Manganese bronze is, for lack of better description, butt ugly. It's a rather yellow gray color when bright, and darkens to almost black when it oxidizes (takes years). Aluminum bronze isn't much prettier, although it doesn't discolor the same way manganese bronze does. Silicon bronze is commonly used for casting, and machines well enough, but it's tough to machine compared to the free machining grades. Decent color, though.

H

[pete]

Then that almost confirms what it is then Harold. It's definately quite red. Given where it came out of on the saddle blocks that help guide the sticks as the buckets crowded in or out on a P&H 1900 electric shovel then it's likely work hardened real well.

[Bill Shields]

It won't hurt to go Bronze if you have it or the $$$ is right....as long as it is an alloy that you can machine.

[jpfalt]

Use the bronze. Generally speaking, the worst bronze is better than the best brass.

[AllenH59]

I have some aluminum bronze, and will use it when it is required... It is a pain to turn..