Re: welders
I own a custom fab shop. I build anything from paper thin to 1/2" plate. I have always trusted the big names like lincoln or miller and own both. There are alot of other brands that are equally as good and have some cool tech from the European sector. My preference in tig welding is Miller. As far as what you require, I learned to weld with a high frequency box and an AC/DC arc machine with a live torch. It worked great. It was far from the toys we have today and if you can weld with one of those setups you can probably look like a pro in a few moments on the new one.
I have a handful of machines in my shop. Miller makes a tiny unit for ferrous (steel) metals that is 150 amps and 13 lbs. Wicked unit!!! You can arc weld or tig weld in DC only. You need AC for aluminum. My preference is my Dynasty 300 c/w liquid cooled torch and cooler. This unit is square wave tech, very adjustable with user memories and preset... kind of like your car stereo saves stations. You pay a large dollar but you should also consider the fact that you can arc weld with this machine, add a spool gun or suitcase mig. Basically I would call it a power source for your welding preferences. The old syncrowave, which you can still buy new is a great machine. There are still lots of commercial and industrial shops using these bullet proof and user friendly machines.
Lincoln is right up there also. I think that Miller has the market cornered in the physical size department but still a lot of good stuff out there if you look. I was looking at a brand Air liquid sells here at our local shop from europe. Size wise it was similar to Miller, function wise it was a better bang for your buck in the mig, tig and arc dept. The next step in Miller to get the same goods was over double the price and a larger unit.
FYI: I have run out of juice on small aluminum projects even with 300 amps. Aluminum is a great heat sync. The size and thickness of the material makes a large difference. 150 amps is good for 1/8" and even up to 1/4 " if the work piece is a 6" piece of 1/4"X2" barstock. It may not be enough for a piece of 3/16" that is a large sheet. I weld aluminum transmissions and engine blocks on occassion... bring your tiger torch to get the heat into the workpiece!!!
As a starter, look for a machine at least 200 amps. Stick to a brand that is well known or is reputable with the local welding supplier. Look for a good used machine... check with the local supplier... they get trades and have to take care of the customer they sell to.
As far as foot pedal, thumb dial, or thumb slide goes, it comes down to practicality for me. I prefer the foot when bench or jig welding. When I am welding on a piece of equipment, especially when I am laying down or standing on a ladder, well it only stands to reason that a foot pedal is kind of clumsy and the thumb is a better choice. I would not consider a machine that has no option of adding either one. The plug is the same on the machine so you can add what you want. You can buy a machine without one of the above and practice, but eventually you will add on, so keep the option open. Actually I am not familiar with any of the new machines not being able to add a pedal or switch.
Anyway this is kinda long winded. If you have any questions, PM me.
Dave :beer;