Depending on what you intend to do and the material you are going to weld will determine the amount of Amperage you are going to need for your projects or jobs. Below in the table is an estimate of what each home welder can do. If you need to go heavier, like 1/2″ plate and upwards  you are going to need a serious welder of 400 amps plus.

Its always better if its within your budget to buy Mig welding machines with more power than you think need, however as you can see by the chart you can achieve much more when you use proper weld preparation techniques.

Take note also of the minimum amperage, this especially applies if you intend to weld light panel work in say a car restoration project, in this case you would be better served with a machine of a 25 amp minimum such as the Hobart mig welder, a 25 – 140 Amp MIG & Flux Cored  Welder.  This type of machine is ideal at home or small workshop when it is unlikely that  you will need to weld heavy steelwork.

Gasless Mig Welder Vs Gas Mig Welder

Mig tig welding needs a shielding gas to keep oxygen away from the weld. The main difference here is that a gasless machine obviously has no gas bottle to carry around, even a small bottle of gas is heavy at the best of times. From experience in my own metal shop where I used both types, they both have advantages and disadvantages.

Gas-less Welders

• Very portable in the smaller amp models, up to 180 amp but the 140 is an ideal welder for light site work. If weight is an issue you can opt for different weld spool sizes to cut the weight down.

• The tip size is smaller on a gasless machine as no gas shielding cone is required, this allows easy welding in a confined space.

• Again the smaller tip allows you to perform very fine welds when using smaller gauge wires, very handy in fabricating decorative work where minimum clean up is needed.

• Excellent for welding galvanized steel

• Produces much more fume and smoke than a gas machine

• More clean up is required as there is a slag deposit left behind, although it can be removed using an electric wire buff, it can be a nuance.

Gas Mig Welders.

• Produces a much better looking weld with no clean up

• Much smoother and nicer to use

• Less smoke and fume

• Easier to see the weld pool and less splatter

• Better for heavy welds where more than one pass is required.

• Extra cost involved with gas bottle refils and bottle hire

Quality

Many more machines are now coming out of China and India. Many of these are cheap and not worth your time if you are serious about what you are doing. You can analyse the price and worth of a “no brand” 30 – 140 amp machine for a hundred bucks to a Miller MIG Welder, 30-135 Amps for $900.00 as much as you like but I know what I would be buying. You will get more value from a quality made welder than several Chinese made models.

This is not to say you have to spend $900.00, there are plenty of good machines in the $300 plus bracket like the Hobart mig welders, Lincoln, and Clarke. These have readily available parts and accessories and are built with electronics inside and better wire feed units.

Controls

A home welder will normally have two controls – one for the power and one for the wire speed. Setting these is a trial and error process as I have rarely come across two machines that work in exactly the same way. A good system if you are starting out is to have a friend slowly adjust your wire speed as you are welding to find the best setting for your job.
Other controls on higher end models is pulse or spot timers, additional control for burn back, and negative / positive earth reversal switch.

My best advise is to keep away from lesser known imported mig tig welder and stick with American brand Mig Welders.