Silver Solder Brazing
The ability to be able to Braze is an asset worth investing in, through out my Hints & Tips Section I refer to Brazing or Silver Soldering which is perhaps the more common form of Brazing.
Solder is a Hard Solder Method and is used for Soldering Tungsten Carbide Tips
to Tool Holders and Tungsten Carbide Tips on TCT Saw Blades etc.
picture left shows the basic equipment requirements all of which are
readily available, from Hardware & DIY Stores, Vehicle Accessory Outlets Etc.
The Torch Head is available in various forms from top of the range instant piezo-electric ignition down to a basic pencil flame torch, the one shown in the picture is a middle of the range swivel head torch.
Most Torches can be used with either Propane or MAPP Gas, I prefer the MAPP Gas as this gives a higher heat [150/200°C Higher] and therefore increases your Brazing Capabilities.
MAPP Gas although slightly more expensive it is well worth the extra cost.
Silver Solder is available in numerous grades I use a general purpose Cadmium Free version with a high Silver content of 35% [typically AG35] which has melting temperature of 680/700°C.
The only other requirement is a suitable Flux, in either Powder Form or Pr-Mixed although this has a limited shelf life, you can also purchase pre-fluxed Silver Solder which can be more convenient.
Some Golden Rules to follow are:-
Prepare and Plan before starting the Brazing.
Clean all Surfaces, no Grease or Oil use a cleaning agent if possible.
Mix the Flux [just enough for the job in hand] in a suitable clean container.
Support the items to be Brazed so you have clear access and ensure that the Torch Flame will be clear of any Flammable materials at all times.
Have sufficient Silver Solder to hand.
Apply the mixed Flux Paste to both areas to be Soldered prior to applying any Heat.
Light and Adjust Flame only when everything is in place.
On completion turn off the Torch and place it in a safe area, the Torch head will be HOT! for some time after finishing the Braze.
Allow the Brazed Joint to cool down before cleaning off any residue of Flux, natural cooling is best, avoid plunging into Cold Water.
Always wear Protective Clothing and Eye Protection.
Only carry out Brazing in a well Ventilated Area and use a Mask.
Always clean your Hands after Brazing.
You can Silver Solder numerous materials and I list just some of these below:-
Copper [No Flux required]
Copper to Brass
Steel to Steel of mixed types [Ideal for Making or Repairing Bandsaw Blades]
Stainless Steel to Stainless Steel [Special Flux required]
It is perhaps the Steel to Steel that you will find most useful and I have Brazed Tool Steels, including HSS and Cobalt, to Mild and Silver Steel, Mild Steel Box Section to Mild Steel Box Section and also Nuts inserted in Box Section for various Jigs successfully.
A point to note is that any material you intend to Braze must be cleaned down to bare material i.e. remove any Coatings, Paint or Coverings that have been applied to the items to be joined, this also includes Rust.
To do the actual Braze you will need to heat the assembly to be bonded as rapidly as you can to a Dark Cherry Red and then apply the Silver Solder to the Joint Area, if the Temperature is correct the Solder will flow into the joint and follow the Heat Source.
If the Heat is too low then the Silver Solder will just stick to the surface and not flow creating a Weak Joint, on the other hand if the temperature is too Hot the Solder will boil and the joint will be Weaker than you should be aiming for.
Providing the preparation is thorough and the Heat correctly applied the resulting joints are strong enough for the typical applications you will be using for Woodturning.
Some useful Links to Web Sites with information on Brazing:-
|The Brazing Book, pages of everything you will ever need to know about Brazing.|
|Brazing Procedures and Techniques.|
|Notes on Silver Soldering.|
|A Brief Introduction to Brazing.|
|The Brazing Process.|
|Encyclopedia of Brazing|
|Principles of Brazing Technology|
|Everything about Brazing|
LaymarCrafts Woodturning is the Web
Site of Richard & Sheila Stapley
Last update 06 September 2007
Web Site Design & Construction by Richard Stapley.