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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: Boiler testers and material verification
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.


Thread: The Chocolate Fireguard as designed by Mercedes Benz
29/04/2019 10:26:04

To bring the thread back on topic.

The A Class comes as standard a Speed Limit Assist programme that provides information to the driver that will help him avoid exceeding the speed limit but does not absolve him of his responsibilities.

The system gathers its information solely from "a low level mono camera". There is no input from any database connected to the sat/nav.

The system ceases to provide any information

1) 10 seconds after passing a sign showing the derestricted speed limit or

2) if the vehicle makes a right or left turn at any road junction


the camera may attempt to analyse the road ahead and will offer incorrect information for the driver to ignore.

These are not a sign of the system not working. The system is designed to work this way. So the customer, apparently has no redress.

Emails from Mercedes Benz confirm this.

Request for clarification along with information about other "assist" packages is now being dealt with in Maastricht.

In my opinion this system which cannot offer information operate in built up areas or on the open road is unfit for purpose. It is only an assist. It is not to be relied on.

The distracting system cannot be switched off. Nor can it be upgraded.

Thanks for your interest.


26/04/2019 09:36:35

A heads up!

I recently bought a Mercedes A Class vehicle. It's Vehicle Identification Number tells me it was built in Finland on Sep 25 2018.

Fitted "as standard" to the A Class is a Speed Assist Programme. It's advertised function is to provide me with information that enables me to avoid exceeding the speed limit.

It gathers the information from a forward facing camera recording speed limit signs. It does not get information from the sat/nav.

All as per the 494 page manual.

The manual tells me that the system does not absolve me from any responsibility regarding the vehicle speed.

The manual does not tell me that the system ceases to provide any information if the vehicle makes a right or left turn at a road junction be it a T-junction or crossroad or roundabout. Information is not restored until the camera sees another road sign. The system cannot provide information in built up areas.

The manual does not tell me that the camera may not see a road sign unless the camera is square on to the sign.

The manual does not tell me that the system again ceases to provide any information 10 seconds after passing the sign of a black diagonal stripe on a white background denoting the National Speed Limit.

The manual does not tell me that the camera will operate in another mode such that the driver receives incorrect information. This includes telling me that a local dual carriageway has different speed limits (depending on the direction of travel) or that the speed limit is 30-mph (incorrect), or the speed limit through Chatsworth Country Park is 70mph (!) etc.


I have emails from Mercedes Benz and a main dealer that this situation is normal. The emails go to great lengths to stress that the system is not failing. It is working exactly as designed. It is not an unusual scenario with the A Class

Like all "Assist" packages, they are there only for guidance. Mercedes Benz are in no way responsible for any result of a perceived malfunction in a system.

Look out for the door mirror mounted ash-tray and perfumed airbags!

The mind boggles as to the disclaimers for the much advertised forthcoming "Assist" packages that will make the roads safer that are being banded about. Packages that will make speeding offences impossible and rear end shunts a thing of the past.

No more accidents in the rain or fog.

And we have yet to see their progress on driverless cars!

Caveat emptor.



PS If anyone wishes to share similar experiences, please email me. This might be worth taking up with Trading Standards, HSE and Avertising Standards Agency

Thread: Silver Soldering :Good and Bad :Flux sometimes a black mess
17/04/2019 09:52:12

Hello Bill

The process is simple as long as you understand the basic principles and STICK TO THEM.

You will be successful.

Read the book from CuP Alloys. It is the result of 50 years experience in the silver soldering business. Or why not simply ring them and get help from the UK's number 1 supplier to the model engineer.

Talk to them face to face at Doncaster next month

The help is there. Just reach out for it!


Thread: Copper for boiler construction
15/04/2019 08:39:05

Hi All,

Get your brazing torch too near to some of the cheaper grades of copper and it will crack. This is caused by oxygen in the grain boundaries of the copper being converted to steam. It cannot escape and the copper fails.

It is referred to as "hydrogen embrittlement".

Avoid the risk.


Alternatively you can always blame the flux, the torch, the gas or even the silver solder!



Thread: Furnace Silver Soldering
02/04/2019 11:30:01

The biggest pitfall will be money.

If you have vast numbers of self jigging components then consider a furnace. If not, then do what the majority of industry does and use gas torches, induction heating, resistance heating (direct or indirect).

I offer you the same advice as I did an F1 racing company who had a similar thought process, but they ignored it because they simply said "money is no object if we get the right result". Result not known!

There are two basic types of furnace - vacuum and atmosphere. But they have to achieve the same result ie that of producing oxide free surfaces into which a filler metal will flow by capillary action into a joint gap

The vacuum furnace involves creating conditions of temperature and pressure where the surface oxides break down and the the oxygen is pumped away. The pumps will also remove any metal vapour produced when the alloy melts. Expect a coating of zinc everywhere!

An atmosphere furnace uses an atmosphere that removes oxides to produce the same effect that a flux does.

Common atmospheres are natural gas, forming gas (5% hydrogen nitrogen) and cracked ammonia. The choice depends on how dry the atmosphere has to be for the oxides to be removed. The dew point of the atmosphere is a measure of the atmosphere dryness. For a silver solder to work and create a joint at about 700 deg C, the dew point has to be about minus 50 deg C! If you cannot achieve that then braze at a higher temperature, in which case why use a silver solder when copper or brass will do.

You aren't brazing copper or brass are you?

Avoid the risk of liquation caused by slow heating, ie the alloy splits as it enters the semi-molten stage. Use a filler metal with a narrow melting range- ideally less than 25 deg C.

Another problem is maintaining the integrity of the atmosphere.

Now I suggest that you talk to Kepston, who, I believe are market leaders in this technology. **LINK**

I have no connection with them other than appreciating they are a sound, reliable company and who have been around in this industry for over 50 years.

I believe that in the event of your not having an F1 budget, they can offer a sub-contract brazing facility.


What a project!



Thread: TIG welding copper boilers.
27/03/2019 09:36:28

Brazing relies on capillary flow between two closeiy adjacent components.

That requires a temperature difference within the joint to promote it. Otherwise the filler metal will not penetrate.

The common result is that you succeed in partially blocking a hole, not filling the joint and leave a crack in the back of the joint.

If you want to weld then weld. Design your joints accordingly. Don't mix your apples and pears!

It's like trying to achieve the combination of performance and economy from an internal combustion engine by mixing diesel and petrol!

Good luck trying to braze and using a TIG torch.


Thread: Brazing teeth
26/03/2019 09:21:48

Hi Grant.

Silver soldering cast iron to itself or stainless or copper alloy is no problem. You simply need to make a slight adjustment to your technique to ensure that you stick to the basic principle of brazing - capillary flow.

For more information see the book or give us a call.



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