grinding crappy welds....welding over with diff. processes

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I was always told that its better to be a good grinder than a good welder.  I'm a certified metal melter, not a welder.  By that I mean I'm not certified for any type of welding, but can stick stuff together at a "hobby" level.  I TIGed an alum. chassis for an off road race car in Engineering school years ago.  Crashed it and flipped it several time.  The cage didn't collapse and I didn't get hurt....so I guess I did OK, and had some luck too.Fast forward 25 yrs. and here I am. Welding some of my own cycles, unibody "fixes".  (ruled of thumb for me?  when in doubt, go overkill).Question 1:  I hear alot of you guys (obviously, good welders) give advice to grind out the old, reweld.   At what point does this NOT become a good idea, lets say on mild steel?  Poor penetration? easy enough to grind off.What about too much heat into the parent metal? grind off the high spots.....then lay some nice beads over?I also hear people saying to burn it some 6010 or 6011....grind......lay over some 70xx rod to make it purrrtee.    ARe you going to stuctural soundness on the ugly 60xx welds and just pretty factor on 70xx?   seems like the way NOT to go.  Just looking for comments.  whats the real fix for UGLY spotty intial welds?   Question 2:  What about different processes over eachother?   If some patchy 6010 welds were laid down on 1/4" mild steel.  Could you grind....clean then MIG over it?   Yes? no? WHY?   Why is stick over stick prefered?
Reply:Two or three trys shouldn't be a big issue, if you need more, then you just need to practice more first., or farm it out. 6010 welds can be a beautiful thing, no need to cover them if well done. No need to recap with 7018 either, 6010 has higher strength than mild steel.
Reply:Originally Posted by bbscampI was always told that its better to be a good grinder than a good welder.
Reply:Originally Posted by bbscampI was always told that its better to be a good grinder than a good welder.
Reply:Originally Posted by bbscampI also hear people saying to burn it some 6010 or 6011....grind......lay over some 70xx rod to make it purrrtee.
Reply:Yes you can mig weld over a previous stick weld. I have many times by just grinding the ridges off and making sure no rust is present. Flux core would be an option if the joint is hard to clean or get to.Fireman BillHH 210 MVPMM 211 Spoolmate 100Lotas LTP5000D PlasmaOxy/Accet (Victor)Wards AC/DC buzz box30 ton old hyd pressA few brand name toolsA bunch of cheap toolsA wife to worry me and4 dogs to supervise me
Reply:I guess grinding out an old weld or just re-welding would come down to strength requirements. I figure if its a fence i'd just re-weld it no problems but if it was a boom or trailer hitch i'd grind out the old weld completely then weld.Lincoln pro core 125 14''chop saw7 inch grinder,2-4.5 inch grinders,electric die grinder.Half inch drillAnd alot of hand tools