Buying Your First Welder

 

A beginner’s guide to buying a welder for light fabrication, maintenance, motorsports, home-hobby, farm/ranch, metal art, automotive and other DIY applications

 

Understanding your Needs


While all Tweco welders let you accomplish many welding projects, there is one series of welders that gives users more flexibility than any other welder on the market: the Fabricator 3-in-1. This portable, integrated multi-process welding system lets you weld using the MIG, flux cored, Stick welding and TIG welding processes. 

 

No other compact, lightweight welder offers more flexibility than the 3-in-1! Review the chart below for a quick snapshot of all the possibilities with its multi-process output.

 

MIG

Flux Cored

DC Stick

DC TIG

Popular uses

Fabrication

Automotive

Farm

Metal art

Maintenance

Home/DIY

Farm

Fabrication

Repair

Hardfacing

Outdoors

Home/DIY

Farm

Repair

Hardfacing

Outdoors

Home/DIY

Automotive

Aviation

Precision welds

Metal art

Metals this process can weld

Steel

Stainless

Chrome-moly

Aluminum

Steel

Stainless

 

Steel

Stainless

Cast iron

Aluminum*

 

* Very difficult

Steel

Stainless

Chrome-moly

Copper

Brass

Bronze

Titanium

Metal thickness

> .025” (24 ga.)

> 1/8”

> 1/8”

> .010”

Heat control

Excellent-Good

Moderate

Moderate

Excellent

Easy-to-learn

Very easy

Very easy

Some skill

Most skill

Bead aesthetics

Excellent-Good

Good

Good

Best

Welding Speed

Fast

Fast

Slower

Slowest

Portability

Somewhat

(requires gas)

Very

(gasless wire)

Very

Somewhat

(requires gas)

 

When buying a welder, consider the following factors:

  • Primary power requirements
  • Portability, size and weight
  • Welding output and duty cycle
  • Electrode selection
  • Shielding gas requirements


Input Power Requirements


Before buying a welder, you need to determine if the primary power you have available (or can have an electrician install) is compatible with the unit. Consult the operating manual or spec sheet and look at requirements for primary voltage (range, phase, frequency), minimum primary circuit size and recommended circuit size (required to achieve maximum output).

For example, the Fabricator 181i has the following requirements:

  • Primary voltage: 208 – 265V AC, single-phase, 50/60 Hz
  • Minimum circuit size: 208 – 230V/25A
  • Recommend circuit size: 208 – 230V/40A (or 230V/50A)


As a general rule, consider the following:

 

  • A welder running on 115V primary requires a minimum breaker size of 20A with 30A recommend (this would be for welding at up to 140 amps). 
  • A welder running on 208 – 230V primary requires a minimum breaker size of 30A with 50A recommend (this would be for welding at up to 180 amps). 
  • Welding at an output of 200 amps or more requires at least a 50A breaker.

Note that some power sources accept different types of primary power. For example, the Thermal Arc 161 and 201 Stick welding and TIG welding inverters accept both 115V and 208 – 230V primary power, as does the Thermal Dynamics Cutmaster 42 plasma cutter.

 

Portability, Size and Weight

In the days before inverter technology, getting the welder to the work site used to be a challenge in many situations. Small MIG welders weigh 70 lbs. or more, Stick welders typically weigh more than 100 lbs. and TIG welders are even heavier. Even moving one of these welders around a shop without a wheeled cart could lead to lower back strain.

 

Welding Output and Duty Cycle


The output or “size” of a welder is measured using amps, volts and rated duty cycle. Duty cycle is the amount of time a welder may be operated at a given output without exceeding the temperature limits of its component parts.

 

Duty cycle is always measured using a 10-minute cycle. For example, the Fabricator 181i has duty cycle of 20% when MIG welding at 180 amps/23 volts. This means the unit can weld continuously for two minutes at this output. It will then need to cool for the remaining eight minutes.

 

Duty cycle and welding output are inversely proportional. When welding at lower outputs, duty cycle increases. For example, the Fabricator 181i has a duty cycle of 60% when MIG welding at 113 amps/19.7 volts.

 

Note that duty cycle is evaluated at a specific ambient temperature. Thermal Arc uses 104o F. Some other industry leaders use this standard, while others use a lower temperature (e.g., 86o F); these other units will need to be “de-rated” when welding in hotter conditions.

 

Amperage and Metal Thickness

When someone asks, “What thickness of metal can that unit weld,” they are really referring to metal thickness that can be welded in a single pass while achieving full penetration.

When buying a welder, consider the following as general rules:

  • A 140-amp unit can weld up to about 1/4” steel
  • A 180-amp unit can weld between 3/8” and 5/16” steel
  • A 200-amp unit can weld between 5/16” steel
  • A 250-amp unit can weld 1/2” steel

Broadly speaking, you need 1 amp of power for every .001” of steel thickness. Stainless steel and welding out-of-position require 10 to 15% less heat input, while aluminum requires about 25% more. Here are some common metal thicknesses in gauges/fractions, decimals and metric equivalents.

Gauge or

Fraction

24

22

20

18

16

1/16

14

1/8

10

3/16

1/4

5/16

Decimal (in.)

.0239

.0299

.0359

.0478

.0598

.0625

.0747

.125

.1345

.1875

.250

.3125

Metric (mm)

.607

.759

.912

1.214

1.519

1.588

1.897

3.1750

3.416

4.763

6.350

7.938

 

When discussing amperage and metal thickness, be sure to consider these points:

1.    Welding thicker metal can be accomplished by beveling the edges to create a V-groove and then making multiple pass welds (often called “running stringer beads”). The heaviest construction equipment and thickest pipe is often welded with a 1/8” diameter Stick electrode run between 110 and 165 amps. 

 

2.    An old trick for increasing penetration on thicker metal is to heat it with a torch until it reaches about 250o F (which you may want to do anyway to drive off moisture).

 

3.    In many applications, using a smaller diameter electrode increases control over travel speed, the weld puddle, weld bead placement and heat input. When welding on thinner metal (auto body work is a good example), good arc characteristics at low outputs (e.g., good arc stability, positive arc starts, low spatter) are far more important than total power.

 

4.    Consider the nature of the projects you plan to tackle. Long, continuous wire welds on thicker metal with larger diameter electrodes will call for a welder with a higher output and duty cycle. Conversely, a Stick welding electrode burns in about 1 minute, after which you need to stop and chip slag. During that time, the welder will cool.

 

5.    The current carrying capacity of the electrode selected dictates maximum welding output. Here are a few common electrodes and typical operating ranges.

 

Stick Electrodes 

3/32”

1/8”

5/32”

6010, 6011

40-85A

75-125A

110-165A

6013

40-90A

80-130A

105-180A

7018

60-100A

110-165A

150-220A

 

Wire Electrodes* 

.024”

.030″

.035″

Solid Steel

30-80A

40-145A

80-175A

Gasless flux cored (E71T-11)

Not made

30-140A

50-155A

Solid Aluminum

Not made

100-150A

110-170A

*Short circuit transfer process. Amperages are approximate and will vary depending on AWS wire classification and shielding gas selected.

 

Tungsten Electrodes 

.040”

1/16”

3/32”

1/8”

2% type

30-60A

60-115A

100-165A

135-200A

 

Shielding Gas Selection


Different processes and base metals require different shielding gases:

  • For short circuit MIG welding, use “C25” or “75/25” (75% argon blended with 25% CO2). C25 produces less spatter and less heat than welding with 100% CO2.
  • You can use 100% CO2 for more penetration on thicker material, but be aware that it creates more spatter.
  • For MIG welding aluminum, use 100% argon.
  • For MIG welding stainless steel, use a “tri-mix” blend of approximately 90% helium, 7.5% argon and 2.5% CO2.
  • Spray transfer MIG welding requires a different gas blend, generally a 90% argon/10% CO2 mix. Basically, the spray transfer process requires a MIG welder in the 200+ amp category.
  • 100% argon is acceptable for all TIG welding applications.

Consult with your welding supply distributor if you have any questions about shielded gas choices. 

 

Notes on Selecting a Stick Welder


Stick inverters make it much easier to learn to weld because they have a “hot start” function. During Stick arc initiation, the rod is prone to sticking because the voltage drops to zero when the rod touches the work piece. Hot start helps to free the rod and establish the arc by automatically boosting the welding current for a fraction of a second during arc starts. Once the arc is established, the hot start function shuts off.

 

Stick inverters also have the ability to adjust arc force or “dig” characteristics. Increasing dig creates a stiffer, more driving arc that helps prevent the rod from sticking when welding overhead or welding in tight fit-up situations. 7018 electrodes especially tend to run better with a little more arc force added, while 6011 and 6013 electrodes favor less or neutral arc force settings.

 

Note that some conventional Stick welders are built specifically to excel at welding with one type of electrode or in one particular application (it has to do with their volt/amp curve, which is an advanced topic). Because Stick inverters with arc force adjustment enable you to adjust the arc characteristics from soft to stiff, you always get the best performance in any situation.

 

People who grew up welding with a classic Stick buzz box and its AC output might be concerned about switching to a DC output. However, if you imagine an electric current flowing only in one direction, it’s easy to picture how a DC output creates more positive arc starts, helps keep the arc established and makes the rod less prone to sticking. These benefits make Stick welding a lot easier to learn! Other benefits of a DC output include reduced spatter, easier out-of-position welding and better weld bead aesthetics.

 

Notes on Buying a MIG/Flux Cored Welder

Inverted-based MIG welders create extremely positive arc starts (little or no popping) and a very stable welding arc with minimal spatter. They can react to changing welding conditions (typically arc length and electrode stick out) extremely quickly and adjust their output to maintain consistent performance. 

 

Inverted technology also makes it affordable to incorporate features found on industrial MIG welders, such as inductance control. Without going into too much technical detail, adding inductance decreases the number of short circuits per second while increasing the amount of arc-on time per short circuit. This creates a more fluid weld puddle (better “wet out”), which in turn produces smoother beads and a flatter crown.

 

Inductance noticeably improves results on stainless steel. The properties of stainless keep the heat of the welding arc very localized. The puddle does not like to wet out, resulting in a ropey looking bead with a high crown. Adding inductance—more arc on time—helps solve these problems.

 

Some features to look for that aren’t related to inverter technology:

  • Burn back control, which improves arc starts by regulating how much wire “stick out” remains after you let go of the MIG gun trigger. If your application requires a large number of arc starts or very positive arc starts, such as for spot welding or on thin metal, you’ll really appreciate burn back control.
  • Spool gun compatibility. Spool guns are considered essential for MIG aluminum, are an easy way to quickly switch to a second type of wire and are a good way to prevent stainless steel wires from becoming contaminated by the steel wire shavings in your regular MIG gun liner. 
  •   A quick note about MIG aluminum: If you plan to weld aluminum in critical applications or on a commercial basis, consider a power source with sufficient output for spray transfer or pulsed spray transfer welding. These processes ensure better fusion when welding aluminum.

Notes on Selecting a TIG Welder


Choose the TIG weldingprocess when you want the best weld bead appearance possible—that classic “stack of dimes” look—or need more precision and control, such as for chrome-moly tubing in motorsports applications.

 

As with MIG and Stick, TIG inverters provide positive arc starts and a smooth, steady welding arc. Industrial-grade TIG inverters may also have pulsing controls, which help increase travel speed and reduce warping in thin stainless steel applications.
Here are other considerations when selecting a TIG welder:

 

  •  As with Stick, the process requires more starts and stops compared to wire welding. Because of this, duty cycle is less of an issue.
  • Use a DC output for welding ferrous metals, titanium, nickel alloys, brass and copper. Welding non-ferrous materials requires an AC output, and here Thermal Arc recommends its ArcMaster AC/DC units.
  • What type of remote amperage controls are available? Some people feel more comfortable with an optional foot control, others prefer the amperage control integrated into the torch while those who are cost-conscious are fine with controlling amperage at the power source.
  • For this latter group, note that the Fabricator 181i incorporates a down slope or crater function that ramps down the current over a period of 1 – 10 seconds after being initiated via the torch trigger switch. Ramping down the current helps prevent crater cracking at the end of a weld (one of the most common flaws).