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Member postings for CuP Alloys

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

Thread: MMA Welding Rods
23/07/2013 10:20:50

Hello John

Go to metrode website.

Select Products

Type in mma

Data sheet says that this rod is for welding stainless steel - particularly 316. All you need to do after is to find people doing this. Might also give an insight as to how much to charge.

Can't offer any more - welding is not our field.


Thread: Silver soldering, I still don't get it.
15/07/2013 14:29:26

HI Ian,

You can embrittle certain grades of copper by using the blue part of the flame. Any oxygen in the copper is converted to steam causing cracking at the grain boundaries.

For ease of mind use oxygen free copper eg C103 and C106.


15/07/2013 12:21:42

Hi Bill,

You are not hallmarking so forget hall marking grades of silver solder. They have a minimum silver content of 68% and higher melting points than necessary.

Use the low melting range, more readily available, 55% silver alloy to do your work. It conforms to ISO 17672 Ag 155 - melting temperature 630 - 660 deg C

Suggest no bigger than 1.0mm dia rod.

Tubal Cain book is excellent, but outdated. Some of the alloys featured MX12, Easiflo, Argo flo are no longer available due to EU legislation banning the sale of cadmium bearing silver solder.



15/07/2013 10:33:24

Hi Bill,

Silver soldering is a very simple process but if you do not stick to the principles of the process you will not succeed.

1) Oxy-acetylene torches in the hands of inexperienced model engineers cause more problems than they solve. The flame is too fierce and localized. The tendency is to not to heat the joint evenly and get it all upto temperature. If you create cold spots the alloy will freeze and not flow.

2) It is difficult with oxy-acetylene to get the heat pattern in a joint that encourages the capillary flow essential if you want successful joints

3) Using propane will overcome these difficulties . It will give you better control over the heat input.

4) You are perhaps adding to the cold spot by holding the work in pliers - a big heat sink

5) Excessive local heat and overheating can/will destroy the flux. Use a long life flux.

6) Heat the components not the solder.

7) Don't use scotchbrite or grit based products for cleaning. They can leave behind residues that the flux (essential for cleaning the joint) cannot remove and lead to pinhole leaks.

8) Pinning the work together removes any joint gap for the solder to enter. Maintain the gap by inserting a piece of foil between the components.

For more info go to Select "Introduction to Brazing" and "Best Brazing Practice" It explains the basic principles of the the process, the whys and how- tos for success.

Silver soldering is basically a simple process. Stick to those principles and you will be successful. Deviate and you won't be.

Success is round the corner!




Thread: Silver solder ?
09/07/2013 08:37:29

Hi there.

Brazing is a means of joining metal, as applies similarly to soldering and welding. It defines the process not the filler metal.

The decision to braze and the alloy used is decided by technical reasons eg temperatures involved, parent metal combination, strength, corrosion resistance, even colour.

If the basic principles of joint design, heating technique and fluxing are not followed, no brazing alloy will work satisfactorily.

There are several forms of brazing alloys.

Nickel brazing alloys - nuclear and marine applications

Gold and palladium brazing alloys - jet engines

copper brazing alloys (brass and copper phosphorus alloys eg silfos)

silver brazing alloys (silver solder)

The success of all depends on the same principles.

Peter - a word of caution re phosphorus containg alloys. They produce very brittle joints on parent materials containing iron or nickel. Such a material was used to braze copper nickel pipes on an american submarine. It did not return from its test dive.

Phosphorus bearing alloys corrode very quickly in hot sulphur containing atmospheres eg coal fire boilers. One of your technical reasons for using silver brazing alloy (silver solder!)

Thread: Silver Solder.
21/06/2013 09:23:37

Hi Alan,

Dave is spot on and for the reasons he says.

DO NOT make a hearth from firebricks taken from storage heaters.

Use lightwright vermiculite bricks or kaolin wool.



Thread: Dates for Harrogate 2014
20/05/2013 18:08:22

Hi David,

We and two other traders have already booked hotel based on May 9th - 11th

Come and say hello



Thread: Cost of Raw Materials
14/05/2013 10:10:15


Clubs and socities already buy in bulk - or as much as their finances permit.

We are happy to do that and promote it.

But collectives already exist! They deal nationwide!

They include Chronos, Proops, Phoenix Paints, College Engineering, Blackgates and even CuP Alloys etc.

To improve (?) on this arrangement and have one big collective would require

  • premises the size of a large supermarket for stockholding, packing, despatch. Consider rates? electricity? water? insurance? etc
  • logistics
  • staffing - wages? insurance? H&S? pensions? NI?
  • ability to satisfy all manner of legislation
  • speciality product knowledge to ensure the model engineer buys the best product to meet his needs and use it successfully
  • finally in excessof £500,000 to stock the warehouse.

The new collective will take this on and offer better prices and service to the model engineer?

  • From our point of view B&Q sell a brazing torch and some brazing alloy and solder.
  • They are cheaper than those we sell - though not for the same product.
  • Delivery is quicker - straight off the shelf - no hanging about for the postman.
  • Ever asked a shelf stacker for technical help?

They are not a competitor to us. Nor, would I suggest, are they to the aforementioned companies.

What reason could there be why the likes of B&Q, with all their financial clout, don't sell over 150 products for joining metal, 100s' of grades of copper alloys and steels, paint in small pots, nuts, rivets, brushes to meet the requirements of the model engineer?

Could it be that the margins are not high enough?

The likes of a super collective cannot hope to compete with the collectives already in existence.

But then again, I could be wrong. The Southern and Northern Federation may be trying to pull all this together. A stockholding of 100 kg of silver solder repeated every 3 months (£70,000) plus the extras is a start. Now for the small steel sections, copper and brass sheet ............

Keith Hale


Edited By CuP Alloys on 14/05/2013 10:17:59

Thread: Vermiculite board for hearth ?
29/04/2013 15:49:31

Hi Dave,

Heating - use a propane burner generating about 7 kw of heat eg Sievert 2941. Get the whole joint upto temperature

Flux - use a long life flux eg HT5

Alloy - use low temperature 55% silver alloy 1.0-1.5mm dia

Heat the joint from the outside and apply rod on the inside or cut a small length of rod and place on the inside. When the alloy melts it will flow towards the heat creating a strong joint.

If necessary hold the pieces together with soft wire to allow expansion and prevent distortion.

Use vermiculite board and/or bricks to build a small hearth.

All products readily available.

For general advice see "Best Brazing Practice" on the website



Thread: First attempt at silver soldering :-(
22/04/2013 09:52:04

Hi Jerry,

Firstly pink flux and flux paste from the plumber are NONOs when silver soldering.

Secondly copper to copper joints can be made without flux if you use a copper phosphorus alloy (CuP) alloy like the 5% silver alloy. (There's a clue there as to how the company took its' name!). Any plumbers paste would have been severely overheated, decomposed and left deposits behind ideal for stopping metal flow. As per OuBallie avoid emery cloth/ scotchbrite as they can leave deposits that can prevent metal flow. Let the flux clean the joint - it is what it is intended for. But copper phosphorus alloys melt at about 760 gegrees and you may be struggling with propane to get the joint hot enough. Use a burner genrating about 7 kw. If you want better fluidity use an alloy with 7%phosphorus and silver free. Place the work on an insulation surface eg kaolin wool or lightweight bricks.

Alternatively use a low melting range 55% silver solder and a conventional white flux powder suitable for silver soldering. Add a couple of drops of washing up liquid to the powder and then mix with water to a yoghurt consistency. Ensure a good covering.

Heat the joint generally getting it all up to temperature unti the flux melts and goes clear. BE PATIENT. After the flux has melted position the heat at 9 o'clock and apply the rod at 3 0'clock. The alloy will get its heat from the joint , melt and flow towards the heat. Result - a strong neat joint using the minimum amount of alloy. Suggest 1.0mm dia rod. Or as JA suggests make a ring but fit it inside the joint and draw the metal to the outside with the heat.

For more info go to Download the sections on "Best Bazing Practice" "Strength of Joints" and "Silver Solder Flux"




Why can't I use copper phosphorus alloys to build my boiler?

The inside of a boiler is a very corrosive environment and any sulphur present from the coal will go through the joint like a hot knife through butter.

Thread: Silver Soldering - reheating.
11/04/2013 12:38:26

Hi Jerry

Suggest you design the end pieces like a top hat that fits inside the tube Joint gap 0.1mm radial.

Flux the joint with silver solder flux eg EF flux.

Drop a piece of 38% silver solder rod (eg 438) say 1.5mm dia into the joint. Heat from the outside moving the torch around to get the whole joint hot. The alloy will melt and flow through the joint.

All you will see is a witness of the solder at the joint line. No machining!

Repeat at the other end with a lower melting point alloy 55% silver alloy (eg 455).

However I suspect that you could use just one alloy the 455. The first joint will have to get rod hot to melt. Ensure this doesn't happen by controlling the heat.

If you require any further information go and see "Best Brazing Practice"



Thread: Geoff Sheppard - sad news
29/03/2013 09:52:43

A sad day.

This gentleman, scholar and genuine good guy will be missed.

Our condolences go to Gill and his family.


Jane, Keith, Glen, Shaun.

Thread: Stength Of Soldered Joints
21/03/2013 17:28:07

Hi Stew,

The informaton you seek is basically unavailable because joint strength is not only dependent on the bulk strength of the alloy (which may be available) but more importantly on how and where it is used. A manufacturer or supplier has no control on these factors and therefore cannot quote any figures.

For instance the strength of a butt joint in tension is dependent entirely on the bulk strength of the filler metal - assuming that is higher than the strength of the parent material! Although soft and silver solders are sometimes used in this manner - they are not intended to be so.

These fillers metals should be used such that the joint is designed to operate in shear ie using capillary attraction to make the joint. Even then there are considerations.

Joint gap - narrow gaps = stronger joints

joint length - too long = possibility of voids / too short = insufficient area to carry the load

degree of penetration - dependent on heating technique

joint design


No supplier can control these factors hence there are no figures. The only solution is for the user "to suck it and see". If it gives you the result you want then use it. Generally speaking there is a technical reason why silver solder is used in place of the cheaper soft solders.

eg its melting temperature,

corrosion resistance

potentially higher joint strength

ability to join dissimilar metals etc

An F1 car can reach speeds of 200mph(?) but not with a 15 stone driver, roof rack, and pulling a caravan. But that is not what it s designed for - hence the ford escort et al.

Finally, when selecting silver solders, the last consideration is joint strengh. Used properly they will all produce joints stronger than the parent metal.


Thread: Soft Solder
19/03/2013 20:56:32

Hi Alan,

The easiest soft solder to use is 60/40 tin lead.

Melting point 187deg C. Free flowing producing small neat fillets.

For small joints as described use paint.

It is 60/40 tin lead powder mixed with a flux and binder. Paint it on the components, assemble and heat gently. Wash with water.

Product is readily available.



Thread: Quality Assured Copper Boilers
19/03/2013 16:16:19

I am pleased to tell you that our customer Helen Stait at Western Steam has just been elected as a Member of the Guild of Master Caftsmen for her range of copper boilers. I believe that she is the first boilermaker to achieve this recognition. Quality is recognized.

Well done girl!


Thread: Work-holding / clamping for silver-soldering
28/02/2013 01:04:47

Hi Jerry,

Remember when silver soldering

no joint = no capillary flow = no joint

Clamping effectively removes the joint gap.

As Chris suggests centre punching maintains a gap. If that is not practical place a piece of silver solder foil in the joint prior to clamping.

Neils' approach of using soft iron wire is also good. The wire deforms as the components expand so maintaining the gap.


Thread: Help needed with Gas fired boiler
25/02/2013 08:53:21

Hi Tom

Sievert produce a range of propane/air burners that generate from 0.25kw to 86kw running off standard propane bottles. One of these should give you the output you require. See the website for details.

Alternatively if you want a ribbon-type burner try birmingham burner ltd

best wishes


Thread: Brazing Stainless steel superheater return
09/02/2013 11:52:24

Hello John

First consideration is to use an austenitic stainless steel to prevent any corrosion of the joint in a damp or wet environment. These are the 300 series.

If you are not sure, use a magnet. Austenitic stainless is non-magnetic

Then use a flux suitable for capable of removing chromium oxide eg HT5

Nothing to choose between the silver solders other than meltng temperature. You pays your money and makes your choice.



PS If your stainless is magnetic you must use a silver solder that contains nickel to prevent that corrosion. Use 449 alloy but it is not as easy to use as say 455 or 438. Easier to use 300 series stainless - readily available from your usual source of tube.

Thread: Terrier Boiler
08/02/2013 21:16:58

Hi Ian,

The grade of copper does not cause the silver solder to crack. It is the effect of the blue zone of the flame acting on tough pitch copper that causes the copper to crack - called hydrogen embrittlement.

As described earlier it could be due to the components moving or are you building a crack into the back of the silver solder by not achieving full penetration of the solder into the joint.

Check joint gaps (0.1-0.15mm) joint length (3 - 4 X thickness of copper) and heating technique to promote the necessary capillary flow.

Also let everything cool down naturally. No quenching - as this can cause unnecessary thermal stresses.



Thread: Bandsaw Blade
25/01/2013 08:17:02

Hi Kevin,

As Kevin suggests make a scarf joint. Make the tapered length 3 - 4 X the thickness of the blade. Allow a small gap say 0.1 -0.15mm

Flux with high temperature flux eg HT5.

Cut a small length of low melting point silver rod - say 1.0mm or hammer a thicker rod down. Place it on top of the joint and heat from below. Capillary action will draw the alloy into the joint. Allow to cool naturally.



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