LBSC & Brazing

[steam4ian]

G'day all

I have been reading LBSC's words and music for Masie. (In an armchair Dr J ;D ;D)

LBSC refers variously to "brazing" "silver solder" and "spelter".

Is it really brazing because LBSC is only using a parafin blow lamp and not an ozy acetylene torch.

I have brazed using an oxy torch with no problems (I can even gas weld) but I would not have thought a blow lamp would have had the heat to melt brazing rod.

Can anyone put a blow torch on LBSC's words and music? What is the difference in LBSC's usage of "brazing", "silver solder" and "spelter"?

This could shed some light on a recent profound disappointment with a Brittania boiler. In the Maise w & m the throat plate to barrel joint is brazed.

Regards
Ian

[baggo]

Hi Ian,

LBSC refered to the process as 'brazing' even when not using pure brass rod. In the same breath he would refer to 'spelter' as the joining material. The material he normally used for 'brazing' in copper boiler work was quote " Note when I say spelter I mean the easy running brazing strip as sold by our advertisers, which is a kind of alloy with a melting point somewhat less than brass". Some he mentions are Cuivrogene, Lafitte (whatever they were!) and 'the easy running strip sold by Bro. Kennion'

Even the likes of Keith Wilson refer to the process of silver soldering as 'silver brazing'.

LBSC did use brass for brazing but usually for things like built up crankshafts etc using soft brass wire.

He always advised packing the boiler with coke during the heating process as that would burn and add a little extra heat. The 'brazing' would be done for the initial joints such as outer wrapper/throatplate joints and inner firebox shell. The rest of the joints would be silver soldered with Easyflo etc.

He actually used oxy once he had the equipment with Sifbronze or 'Poro'

John

[kwil]

Johnson Matthey refer to the materials we use for silver soldering as Silver Brazing Filler Metals, which I think is a very precise statement by those who should know.

[baggo]

To quote from the JM website re brazing:

"It is a thermal joining process in which a molten brazing filler metal is drawn into a capillary gap between the metals being joined. Brazing filler metals have a melting point above 450˚C but always below the melting point of the metals being joined".

So brazing refers to the process temperature rather than the filler used. LBSC was therefore quite correct in using the term.

The joining process using fillers that melt below 450 °C is 'soldering' As Kwil says, brazing with silver bearing fillers is silver brazing rather than silver 'soldering'

Looking on the net reveals a couple of definitions of spelter. One refers to spelter as being slabs or ingots of zinc after smelting. The other refers to an alloy of zinc and copper in equal parts (brass) using for brazing which is what most of us think it as. Probably the free running brazing strip LBSC refers to is actually spelter which would have a lower melting point than ordinary brass which presumably would contain more copper than zinc?

Oh well, I've learnt something anyway

John

[alanstepney]

John has supplied the answer and is quite correct.

However, dont decry the parrafin blowlamp. (Or the petrol ones either.)
It is quite possible to melt copper (or blow a hole through it whilst silver soldering).

Dont ask how I know ! lol

[baggo]

Dec 22, 2009 7:29:19 GMT alanstepney said:

However, dont decry the parrafin blowlamp.

I wouldn't fancy using one of the 5 pint jobs though

Probably more lethal than a Sievert 2944 on full bore!

[goldstar31]

Of course LBSC was NO welder!

He hit porosity so many times and had to stop leaks all over.

Now then, why?

GS31

[paulspeakman]

used a 5 pint blowlamp many years ago on a 5" A3 boiler as backup heat to the masters propane both were beasts !!!