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Member postings for CuP Alloys 1

Here is a list of all the postings CuP Alloys 1 has made in our forums. Click on a thread name to jump to the thread.

Thread: Brazing demonstrations
20/11/2019 11:59:29

Regular readers of these pages will know that I have, for many years, been banging on about how to achieve strong leak tight joints by sticking to the basic principle of silver soldering - namely capillary flow. This principle applies no matter which alloy you use or from where you get it.

Now my good friends at CuP Alloys have transferred the written words into two video clips to show this principle in operation

The first shows metal flowing under capillary action to produce the joint.

The second shows the flame characteristics of various propane burners (possibly used in association with oxy-gas torches) that will produce the heat patterns to promote the metal flow.


Silver soldering is a simple, albeit skillful, operation. It requires no shortcuts. To attempt to do so will, and does, only result in tears! Every model engineer should aquaint themselves of the content of the videos and apply it.

They also have an excellent book that explains why sticking to the principles is so important.

And for those who demand transparency - I am retained by CuP Alloys and the book is mine!

Fruitful viewing and reading!



Thread: Silver solder
16/11/2019 16:26:10

Hi John

Talk to these people.

They have rods from 0.7 to 3.0mm plus wires, foil and paste.**LINK**



Thread: sievert cyclone burner
03/11/2019 13:26:58





02/11/2019 18:16:15

Your requirements are precisely those circumstances that the cyclone is designed to meet

Alternatively, use an oxy-acetylene torch.

It's a no brainer!


Thread: Resistance Soldering question
10/10/2019 09:23:52

Hi Patrice,

What do American Beauty (the supplier) have to say?

Is the clamping pressure too high?

Googling American Beauty only shows a film involving Kevin Spacey?



Thread: Boiler build abandoned !
28/09/2019 09:31:43

The "trick" to all successful soldering, including silver soldering is capillary flow. This is facilitated by joint design, fluxing and heating technique. It matters not about heat source, alloy or manufacturers.

This statement is built on an honours degree in metallurgy and 50 years in the brazing and soldering business as a salesman, technical consultant and manufacturer of brazing alloys.

For more information see the book available from CuP Alloys. Holiday time does not allow the time on this occasion for a fuller answer.

The plot is simple, there are few characters, it won't win a Booker Prize, but it's a good read. My grandson is starting to produce sound joints. He might not understand the science but he does follow the basic principles.

Thread: Boiler testers and material verification
07/08/2019 11:48:17

And this certificate goes further than a certificate of analysis?

Guarantees joint strength, integrity, freedom from fear of hydrogen embrittlement of the copper by a flame, a ductile joint between aluminium bronze and steel, freedom from liquation, corrosion resistance etc?

Such a certificate would open the door for claims for compensation for any cracked or leaking joint.

I have the t-shirt. 13 years ago I saw such action from an ill-informed individual armed with suspect analysis of the silver solder used. The solder was said to be causing weak and brittle joints. It was alleged to be the tip of the mountain of more claims. The truth of it all was that the silver solder was to speciation and the problem was a mixture of inappropriate parent material and brazing technique and joint design. The problem was behind the torch - not in front of it!

There wasn't, and has not been , any further problem.

So don't think it can't and doesn't happen.

The scars have healed but the memory remains as vivid as it was last week.

I am surprised that any company would give this assurance.


07/08/2019 09:14:12

And all this assumes that you have made the correct decision in your material selection. You may have decided that a certain alloy is the one for you. It is not unreasonable for you to ask for confirmation of the material analysis. I have been suggesting that the for years with regards to silver solder. However no material or supplier of any product can issue a performance guarantee unless you provide full details as to what you intend to do with it.

In the case of any material, poor performance could result in the loss of life. Now there's a claim.

In the case of silver solder, For just a start I would want to know;

where, how, when, it was being used. Information required would be a method statement detailing the joint design, heating technique, parent material preparation.

I would also like confirmation of your internal arrangements to ensure that you are meeting the design criteria and production techniques.

Add to that, details of the experience, training and competence of any person likely to use the alloy. Don't forget the qualifications of supervisory personnel.

The list goes on! That is why even the biggest suppliers offer the disclaimer of it being your responsibility to establish the suitability of using their product.

The answer to any problem relating to the quality of any joint be it soldered, brazed or welded probably lies in the same place - behind the heat source!

In the past, I supplied a very large film company with alloy. Then the studio decided that all orders had to be on official letterheads. Their conditions of purchase and the responsibility that I faced ran to 17 pages! At the end of page 1, I was smiling. Page 2 and I was angry. The document went into the bin before the end of page 3!

Their supplies dried up and they went back to using their petty cash fund.

In essence, if you are not prepared to accept the responsibility of your actions ; beware of what you ask for.

Now- about this certificate you want.......



Thread: Dangerous 2" Scale BB1 Boiler
26/07/2019 07:42:12


The strength of a brazed joint in a boiler is not going to be influenced much by testing upto 150 or 200 psi.

Check out the strength of annealed copper. It is way above the operating stresses of a boiler.

The model engineer has a far greater influence. In order to achieve high integrity joints he has to ensure that all parameters are met to create a sound joint. And that means creating the right conditions for capillary flow.

Is the joint gap and length correct?

Is the joint design appropriate for the operating conditions?

Is the right flux being used to meet the melting range of the filler metal, to remove all the oxides present and the time taken to melt it?

Is the joint being heated correctly to promote capillary flow and ensure penetration of the filler metal into the joint?

Is the appropriate grade of copper being used and not a cheap equivalent?

The responsibility for the quality of a brazed joint lies solely behind the torch, not in front of it!

Isn't the technique of gradually increasing stresses during testing simply one of prudence? Does anyone, when testing any new machine,start by winding it up to full bore immediately? If anything goes wrong the ramifications are often less severe. Increasing the loads gradually usually leads to increased confidence.

That is certainly the case with a boiler. It has nothing to do with increasing the strength of a brazed joint. But, I repeat, if it makes you feel good......



PS The source of my information is a metallurgical degree and 50 years spent trying to ensure that every brazed joint is a sound one.

Thread: Brazing Materials
25/07/2019 14:10:21

Hi Nick,

Here we go again............

Don't understand the "true brazing" bit! Brazing is a process of joining metal and its success depends on capillary flow. Brazing has nothing to do with the filler metal used! You can braze with copper, silver, gold, palladium, and nickel alloys

You can use sifbronze on your boiler, you just need heating equipment that will give you the extra 250 deg C to melt it compared to using a silver bearing brazing alloy.

You will probably need an oxy acetylene torch working alongside your propane torch.

You will probably need to enter contracts, bottle hire agreements, increased storage issues to satisfy your gas supplier.

But yes, it can be used. It's just easier with a silver brazing alloy. OK it's more expensive but easier. You pay your money and take your choice.


Spelter is an old word used to refer to a brazing alloy. Who knows what "easy running strip" is? Probably a name adopted on a shop floor in the antiquities of time!

As for the cheap stuff on your link - why not ask the supplier? Let the buyer beware!

For more information see my book based on 50 years experience in the brazing business. Or talk to CuP Alloys. They will tell you.



Thread: manual wanted
19/07/2019 06:59:14

Hi Paul

After googling "Colchester student mark2 manual" apparently there is a free download available!



Thread: Silver soldering cast iron?
19/06/2019 10:11:17

Hi Alan

Yes it is perfectly feasible.

As Jason suggests, first heat the cast iron to red heat in air, (no flux) to burn off the carbon. Allow to cool naturally and clean with a stiff wire brush. Apply a long life flux, like HT5, and proceed normally.

I wouldn't recommend sand blating. If the sand gets into the surface of the cast iron, you would be in a worse place than when you started. You definitely cannot silver solder over sand!



Thread: Fire bricks
23/05/2019 11:01:57

With due respect to Jason and fizzy, they have both overlooked the big advantage that firebricks and storage bricks have is that they will keep the workshop warm long after you have finished brazing. All that heat put into the bricks and not the work has to be dissipated eventually.

You have burnt the gas, shame not to get any benefit from it.

Stick to light, low thermal capacity bricks and/or kaolin clay blanket folks.

Let's do things properly


PS Jason and Fizzy otherwise are spot on!

Thread: Oxy hydrogen torches
22/05/2019 19:14:52

Hello John,

Before making any decision, seek advice from Amazon and eBay as to the thermal characteristics and brazing capability of the equipment you plan to purchase. Then follow it.

Alternatively seek advice from a company that will understand what you think want to do. History shows that despite its apparent high cost, silver solder can produce the cheapest cost per joint.

I declare an interest. I have for nearly 50 years been selling silver solder and brazing alloys including sifbronze type alloys.

Unless you intend producing a considerable amount of steel components, on balance, buy a simple propane torch and use a silver solder.

Talk to CuP Alloys. They will put you right. Declaring another interest - I used to own the company.

But unlike other companies,they have a reputation to maintain in this market. Amazon and eBay have built a reputation in what field?



Thread: The Chocolate Fireguard as designed by Mercedes Benz
20/05/2019 09:48:39

Hello John

In this case 2 pages!

The rest has been a version of "chinese whispers"

The number of views and posts is of personal interest. It indicates to me that the design features that are apparently built into the system to cut off the supply of data to the driver may not be as common as Mercedes imply. (?)

Still looking for another A Class with similar design features.

Thanks all.


Thread: Brazing torch
12/05/2019 10:39:23

Hi Stephen

Patioheaters and similar devices eg camping stoves and barbecues operate at 37mbar.

Brazing torches operate at 2 - 4bar. That's a ratio of 500 - 1000. That's an interesting engineering project to create a universal system

It's cheaper, quicker,safer to get a propane cylinder with the correct regulator. Then buy a Sievert torch. Buy it from the right source and you will get all the technical help imaginable to ensure that all your brazing projects are successful.



Thread: The Chocolate Fireguard as designed by Mercedes Benz
11/05/2019 08:44:24

But remember, no matter how much you may pay for your"assist programme" there is still the situation that you as the driver are ultimately responsible for any set of of circumstances that may arise. The systems are not to be relied upon.

Parking Assist - you are to ensure that there are no low speed collisions.

Reversing camera - get out of the car to ensure that there are no obstacles that the camera can't see.

Parking sensors - see reversing camera.

Traffic lane assist - keep your eyes on the road! Really? Don't rely on the display on the console.

Braking assist - ?

Speed limit assist - that shuts down when passing some road signs, or the car turns right/left or provides incorrect data or doesn't see a sign. All this is the responsibility of the driver. Learn the Highway Code!

If the system cannot be relied upon, then what is it worth? And what makes it even more damning, is that these shortcomings are designed into the system. In that way, a manufacturer is absolved of any responsibility of anything because the system has not failed. It meets the manufacturers internal specifications.

So whatever you want in the future, don't rely on it being given in a form that is of any real use to you.

The performance of the driverless car will no doubt be the responsibility of the driver!


Thread: Soft Solder v Silver Solder
09/05/2019 15:54:06

There is nothing illegal about using cadmium or lead bearing solders.

To supply or "place on the market" is when the fun starts. A trading entity cannot provide samples.

Like you, I've got enough of both to meet my needs.

So, I do not have a problem.

The generals in Brussels who control the number of holes in the salt pot and outlawed refillable olive oil bottles, do not have a problem.

They do not have to try to enforce the law.


PS The war chest now stands at £0.00

09/05/2019 08:47:41

Hi all.

Let's open the can of worms and disturb the hornets nest!

Lead bearing soft solder has been banned from potable water systems for years. No problem.

It has been banned from electronic products due to a perceived increase in the lead build up in the water table as these products find their way to landfill sites. No problem.

It has not been banned from sale to the professions eg plumber, metal sculptors. The key word is professional.

It has been banned from sale to the amateur and that includes the man in the street- Joe Public.

The fact that tin-lead solder is still readily available does not detract from that. It is simply testament to another fact - it is proving impossible to monitor and police.

If necessary, you can always create a letterhead describing yourself as a plumber or get a friend to get it for you who knows someone that uses it professionally!!!

You couldn't make it up!

It is not my place to go into more detail regarding conversations / discussions / instructions / warnings with and from Trading Standards and HSE..



PS If there are any readers who want to fight the above or challenge the ruling in the UK or Brussels, please send me an email. I will provide bank details for all financial contributions to the war chest. Shall we say a minimum sum of £10,000 per person! 500 contributors should set the ball rolling.

Thread: Brazing steel
30/04/2019 07:58:15

Hi all.

Back onto more familiar ground from that of the Mercedes Benz chocolate fireguard!

Using a silver solder to braze steel presents no problem. The common difficulty is not realising that steel needs more heat to reach brazing temperature. A little patience or a bigger burner and a longer life flux eg HT5 normally overcomes.

The difficulty with leaded steel is that the lead is not alloyed but is present as little globules of free lead. It sits there on the surfaces of the joint. As the joint is heated, the lead melts. When the silver solder melts later, the two mix.

Lead in silver solder makes it less fluid or free flowing. It can affect the penetration of the alloy into the joint and hence the joint strength.

Reduce the effect of the lead. Dilute the lead content in the filler metal by having a larger joint gap say 0.2mm.

Thereafter carry on as normal. The same principles for successful brazing apply. It's still all about capillary flow.


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