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How to Weld - MIG Welding

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Step 7: Grind down the weld

Picture of Grind down the weld
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If your weld isn't on a piece of metal that will show, or if you don't care about how the weld looks, then you are done with your weld. However, if the weld is showing or you are welding something that you want to look nice then you will most likely want to grind down your weld and smooth it out.

Slap a grinding wheel onto an angle grinder and get started grinding on the weld. The neater your weld was the less grinding you will have to do, and after you have spent a whole day grinding, you will see why it's worth it to keep your welds neat in the first place. If you use a ton of wire and made a mess of things it's ok, it just means that you might be grinding for a while. If you had a neat simple weld though, then it shouldn't take too long to clean things up.

Be careful as you approach the surface of the original stock. You don't want to grind through your nice new weld or gouge out a piece of the metal. Move the angle grinder around like you would a sander so as not to heat up, or grind away any one spot of the metal too much. If you see the metal get a blue tinge to it you are either pushing too hard with the grinder or not moving the grinding wheel around enough. This is can happen especially easily while grinding thing sheets of metal.

Grinding welds can take a while to do depending on how much you have welded and can be a tedious process - take breaks while grinding and stay hydrated. (Grinding rooms in shops or studios tend to heat up, especially if you are wearing leathers). Wear a full face mask when grinding, a mask or respirator, and ear protection. Make sure that all your clothing is neatly tucked in and that you don't have anything hanging down from your body that could get caught in the grinder - it spins fast and it can suck you in!

When you are done your piece of metal might look something like the one in the second photo pictured below. (Or maybe better as this was done by a few Instructables Interns at the beginning of the summer during their first welding experience.)

 
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Spudmuffon1 year ago
When grinding run parallel to the work not side to side save that for corner sanding with a 9in. Take the welds down to about 3/32 or so and have at it with the 9 in sander you will have much nicer results
tenfingers4 years ago
I am aware that the guard on a grinder sometimes gets in the way, but not enough to leave it off all the time!
Work safe, use the guards that the tools come with.  If they weren't necessary the manufacturer wouldn't have put them on.
If it's in the way take it off, but replace it when that part of the job is done.
Grinders are made to remove hard metal by abrasion. Imagine how well they will work on soft flesh!
and it goes without saying, when you shut the grinder off, stop the disc, using either the piece that you just finished grinding, or the metal table it doesnt matter what, make sure it is not moving

i only bring this up because i just finished taking a formal MIG welding class, and another student tried handing me a grinder, abrasive disc first, while it was still spinning,
after telling him to stop the wheel and to never do that again, he tried to tell me that i was ok, because i was wearing leather gloves and a leather sleeve over my welding jacket,

bottom line: pay attention and be safe, and as toyotero said use your brain, especially when others dont
obrie0214 years ago
 kinda like having a circular saw with a malfunctioning blade guard and setting it down after cutting a board while it's still spinning down. It WILL crawl up your arm and do some serious damage. Personal testimony. Same thing for that grinder. One normally flips it "on its back" and lets it spin down but you can never be too safe with power tools. Leave the guards on.