The Shed – September-October 2019

losing their mechanical properties. Most
gasless wires are very stiff and have
excellent column strength. This allows
for ease of feeding from the rollers
through the torch and out the tip into the
arc and weld pool. They do leave quite a
lot of residue though, which can be easily
cleaned up with a wire brush. Flux-cored
wires require a knurled V-groove drive
roll that will grip the wire. The texture
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Voltage
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to changes in voltage and so require

a good power source with good arc

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make sure that you have the correct

voltage for the wire size and the wire

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nothing lies between the molten weld

metal and the atmosphere except for the

slag and internally produced shielding

gases. Too high a voltage will increase

the arc length, which in turn will

broaden the arc cone or arc width. This

longer, broader arc has more exposure

to the atmosphere. Proper arc length

is very important, and this is where a

good power source can help maintain

that constant arc length. If the voltage

is too high, gases formed as the weld

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holes in the weld. Any trapped gases

remaining create a very brittle weld

metal with poor strength and mechanical

properties. This is called ‘porosity’. The

molten metal must always be protected

and shielded from the atmosphere until

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Stick-out

Before you start the arc, be aware of your

stick-out. Flux-cored wire should extend

up to 20–30mm for most standard

welding procedures. A stick-out too long

will produce a short unstable arc with

excessive splatter. I like a stick-out of

around 20mm for 0.8–0.9mm gasless

The stick-out for a gasless wire

Hard wire stick-out
Feeding gasless wire. Note the groove is
knurled for grip

Gasless wire leaves some slag and residue... ...that scrubs off easily