To clean or not clean?

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I am a nooby. I meticulously grind every joint before migging, I see many don't. Would i be wrong to skip the grinding for non critical welds!? I'm good either way, but pre grinding / sanding the joint is time consuming
Reply:Good prep makes a good weld. Mig won't tolerate a ton of rust, dirt and paint. Mill scale is so so, depending on what machine you have, thickness you need to weld and so on. If you are pushing a small mig to the max, it probably pays to get things as clean as possible. If you are welding say 3/16" steel with a 250 amp class mig on the other hand, you have plenty of extra power to burn thru the mill scale to a limited degree.I won't say I grind every weld I do, but I usually try to hit most things with a grinder. Mig practice at the tech school is usually done right over the mill scale on the 1/8" pieces. The 3/8" beveled joints do get ground however to remove the flame cut surface of the bevels..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:You'll be hard pressed to find a situation where cleaning the metal ever made the weld worse or weaker. "The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Hello Eliotmay, the other guys have given you the straight-up story with regard to material grinding/cleaning. Part application, material make-up, and engineering often has a lot to do with the amount of grinding/cleaning that will or needs to be performed. Machine type and size, gas type or make-up, electrode type/grade, and other variables will have an influence as well. Primarily, for hobbyist, if time isn't an issue, or if $ don't enter into the equation, you will generally always end up with a better and more visually pleasing weld if you clean the weld joint first. If you are out to make money, for whatever reason, then you need to consider the intended use of the part or any other variables and whether there is justification for this additional step. When possible I do grind/clean. Best regards, Allanaevald
Reply:Proper electrode selection and the right current setting will burn through moderate amounts of mud, rust, and scale etc.  6010 or 6011 are often used for this purpose.I offer three choices: Good, Fast, & Cheap. You may pick two.Hobart AC/DC StikMate LXHarbor Freight AD HoodHarbor Freight Industrial Chop SawDeVilbis 20 Gallon, 5 HP Compressor
Reply:seems to me the only advantage of a wirefeed system is speed, efficiency,production work.  so as Allan says, if dollars is driving the decision, the joint's requirements  will determine if cleaning is needed. if its a bridge beam, clean it. if its a lawnmower just dont use a 110v   and then drive it on a highway...if its hobby work clean it so it looks good and is strong..
Reply:I think my welds always look better and are better when I clean up with a grinder first. I have had people suggest I "weld through" paint, rust and stuff.  I tell them I am not that good of a welder and need to grind off anything that is not clean metal.This makes me a better welder in my opinion.  Just try it, weld a piece with mill scale on and with mill scale ground off.  LOOK closely at the welds. There will always be folks that tell you just use 6011 and turn up the heat.   Well if you clean the weld, use the proper rod and the right heat, I promise you will have a better weld.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by SandyYou'll be hard pressed to find a situation where cleaning the metal ever made the weld worse or weaker.
Reply:Takes 2 Minutes To Clean For A Weld - Takes 30 To Grind Out And Redo - Doing It Right The Frist Time Save Alot Of Trouble Down The Road
Reply:The only time you should not grind is if you cant aford the metal loss.  Like grinding the machined face of an aluminum case. Of course there are ways to clean with out metal removal  Mac
Reply:I don't use much in the way of grinding wheels these days.  The majority of stuff I weld on is mild steel.  I find a flap wheel much easier to use (vibration on the hands), leaves a better finish, and quieter.  It's also easier much easier to control the material removal rate.Always weld a clean surface. Originally Posted by SundownIIIDon't get me wrong.  They are just as ill informed about politics as they are about welding, they just post more on that subject.
Reply:Just how long does it take to grind or flap disc a joint? Keep your grinder close to your work it will take longer to put on your shield and safety glasses than it does to prep the joint. You only have to remove the mill scale and or rust just in a little wider area than what your bead will cover. This is a habit that is good to get into. I'd rather spend a little extra time on prep than a lot of time on doing something over. Good prep habits lead to quality projects. This is the same whether they are for your use or a customers."Liberalism is a mental disorder" Dr. Savage