Hey bigsal, it looks like you beating adversity and doing a great job! I really gotta hand it to ya cutting all that steel with a 4 1/2 inch angle grinder with a cut off wheel! I have been there... You might want to try a
9" Heavy Duty angle grinder from Harbor Freight, it really cuts like a mutha through that 1/4 inch, lots of power and the disks last alot longer since they are 9 inches!!!http://www.harborfreight.com/cpi/cta...emnumber=93179
Like Mikey said the 6011 or 6013 will work much better for ya. That welder you have is an AC 95 amp so you are gonna have lots of fun trying to weld 1/4 inch!! 7014 likes a clean surface and runs a nice pretty weld with a DC machine. I know you are probably not gonna go out and buy a bunch of new equipment and you can probably make your stuff work, but you really should think about getting a different welder! Now I am not gonna tell you to go out and get a Miller or some other expensive high end welder but I do have just what you need for what you are doing and you are probably thinkin I am so kinda Harbor Freight freak but you really gotta check this little beast out!!! Don't be fooled by the size and amp rating cause it will blow you socks off. I have a Lincoln 180 mig and a Miller Thunderbolt AC\DC but I use this little thing all the time. It is an 80 Amp DC Inverter Arc Welder and like I said don't be fooled by the amps cause it runs like 130 amps and the duty cycle at full power is 35%. I have yet to get mine to go out on thermal protection. I burned through 3 sticks in a row and it just kept goin. Best part is that it doesn't stick to your work and the arc is smooth and solid. I got mine for $120.00 with a 20% discount.http://www.harborfreight.com/cpi/cta...emnumber=91110
Here is a video of a guy doing a demo with it and he welds some 1/4 inch plate.http://www.youtube.com/watch?v=bujvEHMcnEE
Here is another great tool that will help you alot! Get your self some Norton alumina zirconia abrasive flap discs!!! They will take down a bad weld or a rough edge in seconds. I say this because it lookes like you were using those hard grinding wheels on those hole that you filled on your tank. Get one of these man and try it! $4.00 can't beat it! I use them to clean whatever I am about to weld also. Your welds will be alot better if you clean the surface before you weld.http://www.harborfreight.com/cpi/cta...emnumber=97627
I hope you don't think I work for Harbor Freight or something but I am poor like most people so I have have to make due! I have been right where you are at and I ended up spending more time and money because I got the wrong tools for the job at hand. Now I have got it down. Please just check these things out at least the 4 dollar flap disk, can't go wrong there!!