Member postings for Keith Hale

First heard 50 years ago that "Nut Screws Washer and Bolts" was a newspaper headline.

It told the story of a physcopath who entered a launderette, had sex with a customer and fled.

Oh well!

Keith

P.S. Forgot to mention,

Remember the high charges quoted by the courier ? (see earliier post)

He is involved in the scam and sues you for his delivery costs ........

just gets better and better don't it?

Keith

SCAM SCAM SCAM

Ketan is spot on.

At CuP we have seen this several times. We have always refused the order. The story as told to me by a bank official unfolds thus;

The cheque/credit card clears.

An unknown courier (with very expensive charges) collects the order

Buyer will claim not to receive his order. Courier will claim that it was delivered and will offer a signature as proof of delivery.

Buyer will claim this is a forgery and will deny any knowledge of signatory.

Buyer will complain to his bank/credit card supplier who will recover his money because they do not want to be involved.

You are left with a dispute with the courier and no goods.

This is a common scam often of Nigerian origin. A variation is to increase the order at the last minute, include tooling or buy something else from you.

Want to secure payment? IRREVOCABLE letter of credit drawn on a London bank payable on sight of shipping documents. Don't despatch until money is in your bank.

Who would be a trader! Wicked world out there!

Keith

Brass expands more than steel. When joining materials with differing coefficients of expansion consider two things.

The required joint gap should be at the brazing, not room, temperature.

When the joint cools, the joint is put under compressive stress not tensile. The solder is, in effect, being squeezed. If possible make the female element of joint steel

Not possible?

Use a larger joint gap than usual. The extra volume of alloy will help to accommodate the thermal stress.

Cool slowly.

Re soft iron wire. Fluxes remove oxides (rust). Keep the two apart or you will add a new feature to your assembly!

For more detailed info go to **LINK**

Keith

Hi Brian.

See my response Feb 16th 2014. You have a flux problem.

Flux is exhausted or the steel is not at temperature,

Or the flux is not compatible with the melting range of the silver solder or the parent materials.

Nothing has changed! go to http//www,cupalloys.co.uk/best_practice/

Keith

The basic principle of silver soldering is capillary flow.

Everything that you do for strong sound joints and be successful is to promote that capillary flow.

For capillary flow to occur there must be a gap.

No gap = no flow = no joint

As described earlier, centre punching or roughing up the surface with a coarse file will help produce a 0.1mm gap. Placing foil in the joint will also work but consider using silver solder foil that you do not have to remove.

Pre-cleaning copper, chemically or otherwise, prior to silver soldering is often unnecessary

At the first instance that you apply heat, you create more oxide on the surface that you hve so painstakingly removed. Joint cleanliness, removing oxides and keeping the surface free of oxide, is the job of the flux. Simply make sure the joint is free of oil and grease which the flux cannot tackle. The temperatures involved will drive off any grease from the hands. Note. This comment does not apply when soft soldering

Use a flux that will operate for the heating period.

If necessary use a long life flux eg HT5. Its residues are more difficult to remove but clean the joint afterwards in 10% caustic soda. Flux which becomes exhausted will not keep the joint free of oxides.

The alloy will always flow to where it is hottest.

Heat the joint in the area to where you want the alloy to flow in relation to where you are applying the alloy. This ensures there are no cold spots in the joint that will cause the alloy to freeze, stop flowing and lead to a lack of penetration. As per Gary

HEAT THE JOINT NOT THE ALLOY

For more detailed information go to **LINK**

Stick to the principles af capillary flow and you will be successful!

Keith

Edited By CuP Alloys 1 on 13/01/2016 13:30:39

Citric acid is safe to use and store.

It tastes foul! Your pets and grandchildren will only taste it once on their learning curve! But it will not do them any harm

Simple guide.

Suggest 10gms/litre or 50gm sachet /gallon of water.

Merry Christmas and Happy New Year to all

Glen, Jane, Keith, Shaun

Bottles for this equipment are no longer available. They leaked. I am told that this equipment crops up fairly regularly at car boot sales and on internet sites at very reasonable prices. £5 - £10. But bottles cannot be found.

We have been told this many times at exhibitions and what bargains they are!

Our product is similar to that bought except with two major differences.Firstly the bottles do not leak and secondly are readily available.

Sorry - our bottles do not fit the regulators on Brians kit - different thread.

It is a good piece of kit for what it is intended - ie precision heating for soft and silver soldering of small components.

Although it produces a very hot, concentrated flame - DO NOT USE IT FOR WELDING. It does not burn sufficient gas quickly enough for welding.

The most common alloys can be found here

http://www.cupalloys.co.uk/for-refrigeration-engineers/

They are readily available. Generally speaking

increasing silver content improves joint ductility

Increasing phosphorus content improves fluidity and reduces melting temperature

keith

Edited By CuP Alloys 1 on 22/11/2015 09:19:06

There is no reason why a propane fired boiler cannot be put together using copper phosphorus alloys (CuP Alloys) that may or may not contain silver.

Gas fired water heaters, central heating boilers are all made using these alloys.

BUT

DO NOT USE THEM ON COAL FIRED APPLICATIONS.

a hot sulphur bearing atmosphere can cut through a copper phosphorus joint like a hot knife through butter!

regards

Keith

Hi Brian,

Suggest you look at www.cupalloys.co.uk/best-practice/

http://www.cupalloys.co.uk/best-practice/

Load your printer and you will end up with a comprehensive book that will answer most of your questions and offer guidance on achieving strong leak-free joints first time.

Regards

Keith

Edited By CuP Alloys 1 on 13/11/2015 13:57:23

Sorry - thats not that then!

Somewhere in the depths of memory is a statement that "a silver solder will have lost 50% of its tensile strength at 33% of its solidus temperature" Does 50% of a large number exceed your test pressures? I believe it does!

You have been using successfully, a very similar product, 455, for years! They both conform to ISO 17672 Ag155! Boilers have remained intact and will do so. The biggest factor regarding joint strengths is the model engineer in so far as he controls joint design, heating techniques, and application of flux and alloy.

When you switched from cadmium bearing silver solder there was no compromise on joint strength. Joints are as strong now as they ever have been.

There are differences between the two products;

an understanding by its supplier of the needs of the model engineer as conveyed in their literature.

the availability of the alloy, by the rod, in small quantities to suit the model engineer and with relevant information.

The support by its' supplier to the model engineer.

455 is the better product

Keith

That'll do for me Diane !

Keith

It is a bit early don't you think, to talk of price increases, organisors/venues pricing themselves out of business, and other aspects of a forthcoming doom.

For "discussions on other sites " do we mean rumours?

From memory, as an exhibitor, I don't recall getting info about Harrogate until the new year when we were able to book space.

Relax! All will be revealed in due time. It is 8 months away. Rather like having a suspicion that a baby may be on the way!

CuP have as great an interest as anybody. If it takes place at Harrogate, they will be there. If it is anywhere else, they will be there.

It is you - the model engineer, who decide on CuPs' attendance at any exhibition and not the organisor. Exhibitions are their opportunities to engage face to face with you. Show you, let you feel, let you see, let you smell the roses etc.

We look forward to meeting you all - wherever it is!

Keith

I assume you have initially used a low temperature silver solder eg 42% with cadmium or 55% cadmium free.

The remelt temperature of both is higher than their original temperature. This is caused by the solder absorbing copper and changing its' composition.

Do a simple test.

Replicate 4 stays in a line. Braze them. Let them cool.

Now set up a parallel line of stays 1/2 inch apart.

Braze them with your low melting point silver solder. Use a suitable burner that will enable you to control the heat. Watching the flux will help you to avoid overheating. As soon as it goes clear your are at brazing temperature. Ensure you also cover the first line of joints with flux to protect them if you do remelt them

Alternatively attach a heat sink where rfequired. This could be a damp rag, a mole grip wrench or apply Pyrocool - a spray product available from Advanced Engineering Ltd Redhill (no connection other than we used to sell it - demand not meeting expectations).

Keith

55% - 56% silver - will both perform equally well for your application.

Get your joint design and heating technique right and, as ever, the joint will be stronger than the parent materials.

Both alloys are readily available in the USA.

Try also Handy & Harman.

I don't know if they will supply small quantities economically. If not try **LINK**

Keith

Silver soldering aluminium bronze? Impossible?

If the aluminium content is less than 2% it is relatively straight forward.

Above that, capillary flow and alloy penetration into the gap does start to become a problem due to the amount of aluminium oxide present on the surface. The flux requires an increase in the amount of chloride ions to remove it.

Buy a proprietary aluminium bronze flux or simply add 25% by weight of table salt to your standard flux i.e.EF.

Mix to a paste and use as normal. The mix is good for upto 10% aluminium content.

Keith

Hi John,

If you can't see the flame, view it against a dark background.

A cyclone flame still produces a blue zone and the hottest part of the flame is at the tip of that blue zone. The whirlwind type gas flow produced in this type of burner creates a blue area that is circular in nature.

Keith

Hi Andrew,

Silver soldering of steel takes longer. Steel requires more heat to reach brazing temperature than copper. It takes longer. Be patient! Watch the flux. When it goes into a colourless liquid you are at brazing temperature

The answer is to stop heat loss (brazing hearth/insulation blanket) and burn more gas. Fit a bigger burner. The 2941 burner generates 7.7kw heat at 2 bar. It might not burn enough gas to generate the heat required.

Or using the regulator, increase the gas presure or fit a 2942 burner.

Use a long life flux eg HT5 that accomodates the slower heating rate and matches the melting range of your solder. Fluxes have a very long shelf life but I suspect 35 years is pushing it a bit! Replace it.

Borax is fine if you are using brass as the filler metal. It does not start to work until the joint is at 750 deg C. Brass melts at 830 degC. Your silver solder melts at what 650 deg ? The alloy may well melt but it will not flow until the flux works.

A real concern is that if your alloy is 35 years old, then it probably contains cadmium. Getting the alloy to the temperatures required for borax will definitely give rise to the production of harmful metal fume. The alloy will also take on an "orange peel" appearance.

Overheating a joint is one of the most common reasons for poor results.

Do not use borax flux with cadmium bearing solders.

Getting the heating right is the skillful bit associated with a simple process! Get it right and it's simple. Get it wrong and it's frustrating (?)

For more info go to **LINK**

Keith

MIG (metal inert gas) and TIG (tungsten inert gas) are welding processes not brazing. They totally ignore the fundamental principle of brazing i.e capillary flow. Joint strength is dependent on the filler metal used not so with brazing.

You can weld with brass filler. You can also braze.Different techniques leading to different results.