Amperages used in Portable Stick Welding

Matching the amperage put out by your stick welding machine and the amperage needed to use a specific thickness and type of stick electrode is the one part of SMAW welding that is more dependent on experience and experimentation than straightforward formulae or common-sense application of technology. There are guidelines, but these must never be put ahead of actual observation – if a certain amperage is recommended, yet when it is used the flux on the outside of the stick electrode begins to burn, then a lower amperage is needed regardless of the printed advice.

All SMAW or stick welding machines adjust the temperature of the welding process by adjusting the amperage that is fed to the welding gun, also known as the stinger. There is no other way to adjust the temperature at which the welding occurs, so changing the amperage is also the way to adapt the heat to the type and thickness of the stick electrode you are using. Needless to say, different amperages and heat levels are needed for welding different kinds of metal and making various depths of weld.

A stick welding machine will have one of two methods for adjusting the amperage delivered to the stinger. The first method is a dial, which can be rotated to different settings within the rated capacity of the welder. This arrangement has the virtue of directness and familiarity – nearly everyone is accustomed to adjusting operating levels on everything from radios and toaster ovens to generators by using a dial.

The problem, of course, is that precise adjustments are often needed, and dials are imprecise by their very nature, so quite a bit of ‘fiddling’ might be required. Because of slack in the dial, turning the setting past the desired point, and then returning to it, is recommended for better results.

The alternative construction controls the amperage with a digital display, which can be calibrated exactly to the amperage output that you need. However, even in this case, the amperage will probably need fine (or not so fine) adjustments to match up with the observed results that you get while trying out the different amperages for a certain task.

As a very rough benchmark when you have no other frame of reference, you can calculate the first amperage to try (which will not necessarily be the best amperage) through a formula based on the diameter of the stick electrode.

Since 1/8” is the smallest thickness of electrode available, this forms the benchmark measurement for the calculation. If you are welding soft metal and/or making a shallow weld, then you should start with 90 amps and work up from there; if hard metal and/or a very deep weld are involved, then 120 amps is appropriate as a starting point. Increase the amperage by 40 for each additional 1/32” of diameter. For example, if you are welding thick metal with a ¼” stick electrode, then 280 amperes is the power level you should start out with, prior to adjustment.