Longevity STICKWELD 140 - Manual (Page 17)

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STICK WELDING TIPS
Arc welders don't have a button to start the arc. Unlike MIG welders the rod (electrode) will
become live as soon as the machine is switched on.
The arc is started by touching the electrode momentarily against the work to complete the
electrical circuit before raising the electrode to establish the arc. This needs to happen
quickly to avoid welding the rod to the work. "Tap Starting" and "Scratch Starting" are the
two common methods of starting the arc.
Because the rod is live at all times it needs to be kept insulated from the earth when not in
use. In the photo the welding bench is earthed, and a piece of wood is being used to isolate
the rod from the bench. After welding the rod is returned to the piece of wood.
Tap Starting
A sharp tap of the rod against the work will remove excess flux from the end of the rod and
create the electrical contact needed to start the arc.
A sharp wrist action should allow a momentary contact with the work before quickly pulling
the rod a short distance away. Too heavy a contact or too slow an action can cause the rod
to stick.
In the video the auto-darkening helmet darkens as soon as the arc is started. The light is
bright at first because the arc length is initially too long. The arc length is quickly reduced
to the correct distance for welding.
Rods start much more easily on the second attempt. It is good practice to first start the arc
on some scrap material before starting the arc at the beginning of a weld.
Scratch Starting
An alternative starting method is to lightly scratch the rod against the work. Moving the rod
against the work removes excess flux from the rod and allows electrical contact from the
steel in the middle. As soon as the rod starts to spark it is lifted from the work to start the
arc.
In the video a backwards and forwards scratching motion is used to remove the flux
coating. A limited movement should mean the arc will start somewhere close to where you
want to start welding. When the first spark is seen the rod is pulled away from the work to
prevent sticking, and then it is returned to the normal arc length for welding.
The scratch start technique is more prone to sticking as it relies on human reaction times.
It can be a useful technique for difficult to start rods, or for AC machines and those with
low open circuit voltage which make Tap Starting more difficult.
Excessive pressure on the rod while scratching will increase it's chances of sticking.