My first MIG welds.

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I bought my first MIG last weekend (MM251) and I've been having a great time messing around with test welds this week.  One of the first projects I want to do is a utility trailer.  I already have a set of plans that call for using mitered 1/4'' angle as the frame.  Below are some test welds with 1/4'' that I made tonight, the Miller was set at 19.5/325, my main concern with the welds are how they will hold up since it is on a trailer.Please feel free to criticize my welds and let me know what I did wrong and were I can improve.Thanks. Attached Images
Reply:HeyI just got my first MIG last week too! Lincoln 100T Ive learned alot since then.Im looking at pic 2 and it looks like you might not be getting alot of penetration. You may be getting enough, but you probably can get more.  I would suggest slowing down the wire speed just a little and try making circles as you weld.  The will make the weld look like it is a row of nickles.Practicing like that is a very good idea.  I find I am getting better every time I practice.Looks good! Keep it up!
Reply:ERR. Slowing down the speed of the wire will make you have less penetration. IF you want to calculate AMPS (measure of heat you´re pouring in the weld) you should check this table. Thus more wire speed more penetration. Best way to know if your welding can hold is a) cutting it on the middle and looking at the penetration of the weld and b) getting a hammer and hit it until its destroyed. That way you´ll know how much your welds will hold.Heeres the table.... Attached ImagesMy Babies: HF Drill pressHF Pipe Bender3   4.5" Black and Decker angle grindersLincoln Electric PROMIG 175that´s it!
Reply:your welds look good for a newbie..if your going to do a trailer and stuff thats over the road..or whatever for that matterwrap the welds on everything if possible..or at least go as far as you can on the backside..without stopping...practice practice practice.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Zapster... why go and go without stopping?
Reply:hey zapster what about the ending of the welds?
Reply:Originally Posted by KRSZapster... why go and go without stopping?
Reply:Just to add a bit about stops and starts...specifically look at the first two pictures.  You stop your weld at the inside corner and re-start on the bottom section.  Maybe this was because you needed to reposition your workpiece...maybe you just wanted to stop and take a look...anyway, you should try to make that weld all at once.  On a piece of angle, I always start from the lower (flat) side and work into the vertical side...I guess this comes from my being taught that vert ups are stronger welds.with a mig welder, you have to anticipate this vertical up portion of the weld.  You can't use the hottest settings for the flat part and expect good results on the vertical part (unless you can somehow reposition the workpiece while welding or change the welder settings on the fly).  This is where practice and experience with the welder comes into play.  Your welds do look like pretty good.  One additional thing that could use a bit more improvement is the fitup of the two pieces of angle.  Good fitup makes even an average welder look really good.  I know this is only practice, but bad habits are hard to break, especially if you practice them.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Originally Posted by ZTFabI don't think zap meant to just go and go and go, throwing weld every which way. What you want to avoid is multiple start and stop points. Everytime you stop the weld bead, it increases the chance for a discontinuity in the weld in the form of a dimple or crater. This is where a crack or failure can start.An easy way to help avoid the start of a crack is to "wrap" your welds. Let's say that you are butt welding two pieces of flat bar together. If you just weld the face of the bar, the weld may hold...but add some torsional twist to that piece and the weld may start to crack at the ends.Now if you take that same scenario but "wrap" the welds around to the backside of the plate, say about 1/2"...the ends won't crack.I think zap's point was to wrap the welds since this is going to be a trailer that will see various loads and a fair amount of tosional twist while it's going down the road, over un-even surfaces. - Paul
Reply:Just trying to clarify one point.  If I try to "wrap" a stick weld on flat bar or angle I wind up indenting the metal at the ends of the joint even though I try to move as quickly as possible to the backside.  Would I just come back later and fill in the ends or is this a flaw in technique?