Good news about my welding class. Original instructor is MIA for some reason, no one will say why, but the woman instructor has committed for the next two classes.. I've just paid for both classes.
My gas saver kit is supposed to be delivered today. The 1/8" rod came in yesterday. Got plenty of it now.
Do I drop the argon pressure to use it since it has better flow and coverage? I can't seem to find an answer to that anywhere.
For learning something new I like having a consistent instructor in the beginning. When you start mixing instructors you often wind up with one liking to do things one way, another liking something different, etc...it can get confusing. I think her committing is a good thing.
As far as gas settings go, I'm going to add a comment that might sound pedantic, but only because someone down the road might read this and it could help them.
People often use the wrong terms when it comes to regulators, flow meters, gas pressure and gas flow rates. A traditional regulator shows the tank pressure and lets you adjust the output pressure. That's what you want for an oxy acetylene torch, but not MIG or TIG welding. A flow meter shows you tank pressure and allows you to adjust the output gas flow in cubic feet per hour (in the U.S.), but the output pressure is fixed based upon the flow meter model. Most flow meters have a fixed output somewhere between 20psi and 50psi. Some flow meters have a bit of output pressure adjustment, but it's not something most people ever mess with.
Here's where this gets a bit interesting. For TIG welding, if you're using a flow meter with a 50PSI output pressure you get a pretty big blast of gas when you first start welding. When you stop welding and the valve closes the lines expand a bit and you actually wind up with more than 50PSI stuck between the tank and the flow meter. If you have a flow meter with a lower output pressure you don't get nearly as big a blast, which is simply more pleasant, and it saves a bit of gas. I once welding with an old flow meter that was set for 80PSI output and it was really annoying! The cheap flow meters everybody sells for $30 to $75 seem to be 50PSI models. Nicer flow meters that are 20-25PSI tend to be a bit more expensive ($100+) but will pay for themselves over time in gas savings. The other thing about the better flow meters is that you can get parts for them if you drop them and break the sight tube, etc.
To answer your question about settings, it's actually pretty easy. Take the cup size you're using and double that to get a starting point for gas flow. With a #7 or 8 cup I start at 15CFH and see how it goes. If I drop down to something like a #5 I'll lower the flow to 10-12CFH. I'd rather have a touch too much gas than not enough...a little too much won't cause problems, but not enough will. Changing flow rates seems to be more noticeable on aluminum because it changes the width of the etched zone so it's something obvious you can see. For steel it's not terribly critical...if the beads are clean, you're good. Stainless is a different animal that can require things like back purging, extra large cups, etc, but in general you'll need more gas coverage than steel or aluminum, so err on the high side for flow rate.
Edit to add: This is somewhat why I hate that companies call these "gas saver" kits. While you can probably save a bit of gas using them, the real benefit is that you can run the tungsten much farther out while getting equal of better gas coverage. Keep the old flow rate and get that tungsten out where you can see it!
