Brass or Bronze?

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Carrdo
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Brass or Bronze?

Post by Carrdo » Mon Oct 09, 2017 5:39 pm

I am in the process of making some boiler fittings for my 1" scale copper boiler and would use bronze over brass if I could identify what I have in the workshop.

Take a look at the attached three photos of some hex material which could be used. What is it brass or bronze or is it a mixture of both?

Is there any relatively straightforward/simple way to determine what is what in a home shop environment?

Ignore the Sharpie pen. :)
Attachments
Brass or Bronze 1.jpg
Brass or Bronze 2.jpg
Brass or Bronze 3.jpg

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Builder01
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Re: Brass or Bronze?

Post by Builder01 » Mon Oct 09, 2017 7:34 pm

Well, bronze rarely is made in hex. Brass is very common in hex. If you are making a copper boiler, I would not make any of the bushings in brass as I assume they will be silver soldered in. They will not be easy to replace. Bronze should last the life of the boiler, brass, maybe not. If you want to make some of the fitting that screw into the bushings out of brass, you could, but, I would not recommend it, especially below the water line. All of the bronze fitting I made for my copper boiler, I had to machine the hex if that's what it needed. A handy tool for machining a hex is the 6 sided 5C collet holder. All you need is to clamp a vice to the milling table, and put the 5C holder in it, and away you go! Takes only a few seconds! By the way, C544 phosphor bronze is good for boiler bushings and fittings on copper boilers.

David

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Wayne Davis
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Re: Brass or Bronze?

Post by Wayne Davis » Mon Oct 09, 2017 7:58 pm

For something as important as a boiler I would order a piece to make sure you know what you have. Cheap insurance!

Wayne

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FLtenwheeler
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Re: Brass or Bronze?

Post by FLtenwheeler » Mon Oct 09, 2017 8:02 pm

I will second what Wayne is saying.

Tim
He who dies with the most unfinished projects: Should of put more time into their hobby.

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gwrdriver
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Re: Brass or Bronze?

Post by gwrdriver » Mon Oct 09, 2017 9:15 pm

Never use a brass (with zinc content) in a boiler, due to de-zincification - the electrolytic phenomenon during which the zinc leaches out and leaves the base metal brittle and porous. The time required for de-zincification is often very short, but how quickly and whether it occurs at all varies by each different boiler. Even so why would one choose to put into a boiler material which has a track record of failure, or potential failure? Copper and gunmetal, while easy to machine and silver solder, have the disadvantage that threads wear, damage, or strip easily, especially where fittings are removed regularly, or need to be drawn up tight.

In general it will pay in the long run to know exactly what you're putting into your boiler. I've always used Phosphor Bronze (C510) for boiler bushes and some stays for a couple of reasons. C510 is tough and harder to machine than common brass and bronze - it turns, drills, and threads much like steel, but the advantages are that it holds threads like steel and silver solders like copper. To me that win-win combination has always been worth the extra cost over copper or a low bronze.
GWRdriver
Nashville TN

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Carrdo
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Re: Brass or Bronze?

Post by Carrdo » Mon Oct 09, 2017 11:57 pm

Perhaps I was not clear in my original posting as for bushes that are silver soldered directly into any part of a copper boiler, I use C510 heavy walled phosphor bronze bushes and thread them no finer than 32 tpi even though M. Evans and LBSC show many designs with ME 40 tpi series threads tapped directly in the copper boiler tubesheets for example.

I, like gwrdriver, have concerns that with repeated use softer bronze threads will wear, get damaged, or will strip easily especially the 40 tpi series. I would consider going even coarser to the 26 tpi series if I were to build a boiler from scratch. Another concern is to get the boiler bushing flange face dead square to the bushing thread and even with boiler bushes that are partially threaded before they are silver soldered in, one can still produce a cocked thread if one is not very careful with the final threading.

But that was not what I was getting at.

Builder01 (David) gave the most practical answer to my question where he stated that bronze is rarely made in hex so for all practical purposes one should assume that any hex stock is not bronze. I have been told this before by locomotive builders I respect.

To that statement I must add a qualifier; the above is likely very true for North America but is not necessarily true for bronze that one can purchase in the UK. Here in Canada (in the past and increasingly less so now due to the cost of shipping) many locomotive builders purchased phosphor bronze hex from various UK suppliers - Blackgates, for example, list Colphos 90 in hex from 5/32"-3/4") and this material can be still found in workshops here.

Reeves in the UK also shows phosphor bronze, in round stock only, but they don't give any specs. on what type of phosphor bronze they supply (at least, I couldn't find anything). So one is left in the dark.

Now things start to get muddy. Here phosphor bronze (C510 grade) is carried virtually by no one and in small quantities just forget it. Ask any metal supplier to make a special order to get you a piece or a few pieces of C510 and they will tell you to get lost. I especially like C510 as it truly has no lead in it (typical composition of C510 is 94.9% Cu, 5% Sn and o.1% P). It is all about the silver soldering aspect as added lead makes silver soldering difficult if not impossible. People swear up and down that the added lead makes little difference in ones ability to make a good silver solder joint and I swear up and down that it makes all of the difference in the world when one has to make a good STRUCTURAL silver solder joint. Colphos 90 for example (it is a phosphor bronze) has a 4% lead content and I won't touch the stuff for structural silver solder work. The silver solder will flow and look good but it will have questionable STRUCTURAL strength and in a copper boiler we want all of the STRUCTURAL strength we can get. Nuffsaid as LBSC used to say.

C510 is not the easiest material to work with especially when drilling it as it will heat up rapidly and seize fast on any drill if one uses ordinary jobbers drills. Then try and get the drill out. If you don't believe me -try it. Yes, I know I can modify the drill point to reduce this tendency but...

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Builder01
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Re: Brass or Bronze?

Post by Builder01 » Tue Oct 10, 2017 4:48 am

Both 510 and 544 bronze are readily available from McMaster-Carr. It can be purchased in quantities as short as 1 foot. Diameters 1/4" to 2", at least for the 510. The 544 can be purchased as short as 6 inches, 3/16" to 2-1/2" in diameter. 544 machines very well.

Yes, all fittings should go into a bushing silver soldered into the boiler shell. Tapping directly into a copper boiler shell is not done any more. I too, have seen this on old drawings!!

David

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Bill Shields
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Re: Brass or Bronze?

Post by Bill Shields » Tue Oct 10, 2017 6:26 am

bronze is available a lot cheaper from Morgan Bronze and / or Bravo Bronze.

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Carrdo
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Re: Brass or Bronze?

Post by Carrdo » Tue Oct 10, 2017 8:44 am

It used to be that McMaster-Carr would not ship to Canada unless you were a business and had a business account with them. Has this changed?

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Carrdo
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Re: Brass or Bronze?

Post by Carrdo » Tue Oct 10, 2017 10:42 am

Bill,

That is all very nice but north of the border we face quite a different situation as many suppliers will not ship here and especially not with small quantity orders. Cross border shipping costs are extraodinarily high also if you can find something.

We have here in the Toronto area a supplier of C510 phosphor bronze (and there is only one that I know of) and if you can get to the President of the company you can get what you need as he was very sympathetic to model engineering people like us (or used to be) but if you have to deal with the duds on the phone or in the warehouse you will not get past the front door.

For certain model engineering applications (copper boiler work for example and it is the same situation with steel boilers) material selection is very important and one has to be very selective (demanding?) as has been pointed out many times here (and I for one am) but with our high requirements and pis...y little orders we are viewed by most commercial enterprises simply as a nuisance to be rid of as fast as possible. It is virtually impossible for them to take the time, effort and problems they will have to make a special order for a small quantity of "unobtainium". So in the end we are often faced with substituting alternative materials which many or may not be the most suitable for the end use intended. This, unfortunately, has been the story of my life when it comes to finding model engineering materials and it plays itself out over and over again.

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Builder01
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Re: Brass or Bronze?

Post by Builder01 » Tue Oct 10, 2017 11:07 am

Well, I certainly am sorry to hear all of this. Have you tried OnLineMetals? They sell in small quantities, but, I do not know the shipping arrangements to Canada. For small quantities, they ship USPS, surely this could cross the border.

Do you know anyone in the U.S. that you visit regularly? Maybe you could have them order from McMaster-Carr for you. Otherwise, you will just have to move or change hobbies!! Just kidding!

There must be a way to over come this problem. These specific metals are quite easily gotten in the U.S. Makes no sense that it is simply impossible to get them across the border in small quantities and without hassle.

Sorry about all of this.

David

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Carrdo
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Re: Brass or Bronze?

Post by Carrdo » Tue Oct 10, 2017 12:14 pm

For interest, I just went to a number of popular model boiler fitting suppliers (water glass, pressure gauges with and without syphons, blow down, check and safety valves and other steam piping valves and fittings, etc.etc.) found on ebay and from their own websites and half of the materials seen there are brass. Not saying this is acceptable but it is out there.

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