Member postings for Keith Hale

My no.1 tip for silver soldering/brazing using a TIG torch as the heat source is DON'T

The heat source is too localized. The whole joint does not get to temperature to facilitate capillary flow. You will not achieve full penetration of the alloy into the joint. You will create a weak joint with an in-built crack.

The shield gas will not remove oxides from the component surfaces which is essential to get the filler metal flowing. You still need a separate flux.

Betcha end up melting the copper and overheating the alloy. You don't melt parent materials when brazing and you don't heat the rod. It is very easy to overheat the alloy and boil off the zinc. (In this instance thank god you're not using a cadmium bearing alloy.)

If you want to weld - then weld. Use a copper welding rod.

If you want to braze - then braze.

But no matter which option you choose - do it properly

Finally

ON NO ACCOUNT USE ANY PHOSPHORUS BEARING BRAZING ALLOY ON A COAL FIRED BOILER. THE SULPHUR IN THE FUMES WILL GO THROUGH THE JOINT LIKE A HOT KNIFE THROUGH BUTTER.

Keith

Hi Alan,

Carbon deposits - from brazing?

Where did they come from? Not the gas, nor silver solder nor the copper.

Or is it that the flux esidues are black? In this case neither citric acid nor sulphuric will help. A more likely explaination is that the flux has been heated too long or to too high a temperature and degraded.

Use a stiff wire brush or other mechanical means to clean things up. Inspect and test the joints.

Stop it happening again by using a longer life flux like HT5

Regards

Keith

Hi Nigel,

Those who have attended the "CuP Alloys Roadshow" over the years will know that we have been banging on since the start about achieving the minimum spend on silver solder. That is best achieved by using it properly and hence efficiently.

Take a little time to appreciate what you are trying to do, why and how to do it it.

Silver soldering is a very simple process but skillful. Stick to the principles and you will be successful. You will produce strong leak-free joints first time , every time and use the minimum amount of this expensive filler metal. Deviate from them and you will not be and the process becomes complicated and difficult.

There have been many a boiler made that should have been hallmarked.

Avoid fillets, examine your joint designs, heating technique and alloy placement.

How much alloy will you use?

Are you planning to use two alloys of differing melting temperature?

Use the thinnest rod practical.

Do not skimp on flux.

You will find all the information you require on the website and in our publications. Call 01909 547248 for a chat. There is the widest range of materials, sizes and 48 years experience in the silver soldering business.

Can't get that on ebay! Or anywhere else for that matter!

Regards

Keith

Hi Chris

Start with a Sievert torch, variable regulator and a 2941 burner.

The kit can be readily adapted by simply changing burners to go from 0.25 kw to 84kw oh heat.

They are readilly availablehttp://www.cupalloys.co.uk/sievert-heating-equipment/

The kit is supplied with all the technical help you may require to make your project a success.

regards

keith

Edited By CuP Alloys 1 on 01/02/2018 21:03:42

Hi James.

Thank you.

If you require any further information, call us. Only too pleased to help.

Keith

Hi Eckart.

Any problems associated with silver soldering are due tothe fact that the lead in the bronze ia not alloyed but is present as free lead. It is present as discrete lead inclusions.

When heated, those on the surface melts. When the silver solder melts later, the molten silver solder dissolves it and and alters the composition of the silver solder.

The silver solder becomes less fluid and penetrating.

Overcome the problem by increasing the joint gap and so increasing the volume of silver solder. This dilutes the effect of dissolving the lead. Result ? Better, stronger joints.

Of course, if the operating conditions allow it, you can always use a tin lead or tin copper soft solder.

For more information**LINK**

regards

Keith

Hello James

Like Russell, I think you have done extremely well to join brass sheet together using Sifbronze No 1 which is basically 60/40 brass doctored with a little silcon and manganese to alter the flow characteristics a little. Its melting temperature is 865 - 895 deg C!

In all cases of brazing and soldering, if the filler metal melts but does not flow - THERE IS A FLUX PROBLEM.(Remember that silver soldering is just one facet of the brazing process)

It matters not what you mix the flux powder with - the problem will remain. The flux is not removing all the oxides present. And no amount of wire brushing at the start will help.

I would suggest you re-examine your technique.

Do a prelininary test to ensure that the flux is removingall the oxides or is getting hot enough to do its job.

Consider using a lower melting point filler metal like a 55% silver solder or a soft solder. The latter was probably used in the first place!

Examine your heating technique. Is it developing the right heat pattern to promote capillary flow. This is the fundamental principle behing brazing and soldering.

For more information **LINK**

regards

Keith

Hi Sam,

Sorry you missed the talk. It was certainly well supported.

Was there anything specific you wanted to know?

If so, send me a pm and I'll try to help.

Regards

Keith

Hi Matt,

Sievert torches are certainly amongst the best in the world.

Look over the water not just the hedge for supplies

The cost of sending a box 25 x 25 x 25cm weighing 10 kg can from the uk to Ontario is about £50.

10 kg covers the weight of a torch, hose, regulator neck tube and a burner. It will cover the weight of several more burners.

Work out what you need and ask for a price.The ex-works prices are available here **LINK**

I will leave it to youto establish any import duty

Email Shaun or Glen. I've retired!

Regards

Keith

one for gluing!

Keith

Borax melts and starts to remove oxides, essential to the brazing process, at 743 degC.

The most common silver solder sold to the model engineer starts to melt at 630 degC.

A major benefit of using a silver solder stems from its low melting point. It is quicker, there is less distortion, less metallurgical degradation. The use of a high melting point flux negates that benefit.

If this benefit is of no interest then don't waste your money. Make your joints with brass.

If it is of interest, along with better oorrosion resistance, colour match, then use a silver solder. But why not then use it properly? Use a flux that prepares the joint for metal flow before the flller metal melts. Why build up increased levels of oxide unnecessarily. You will get better joints.

I believe that Bakers Fluid 3 has undergone two levels of dilution from Bakers Fluid.

A concentrated form is readily available. Pick it up at exhibitions without the high delivery cost incurred because corrosive liquid fluxes cannot be sen in the post.

Keith

To prevent any confusion.

The oxy-turbo kit runs off disposal canisters of oxygen and mapp gas. The oxygen lasts about 20 minutes. The gas about 40 mins. Replacement canisters are available via CuP.

The demo at the Midlands featured preheating with a conventional propane torch before using an oxy-propane flame to reach brazing temperature and create the necesary heat pattern. This kit runs off larger refillable cylinders. One of the major benefits of this kit is that you own the cylinders which you simply pay for their refilling. There is no cylinder rental fee, no maintenance charges or contract. They are your cylinders. Refills are readily available from gas suppliers but not CuP.

Both are good products to meet different needs.

Keith