Grinding welds
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Laughing Gas
Joined: Jul 2004
Posts: 769
Likes: 3
Grinding welds
Hello
I am trying to grind some really bad welds and am useing a 4 1/2 inch grinder. Problem is that it will take too much off and they are in a tight spot. Can anyone suggest a type of smaller or better grinder for finishing off the weld..
Thanks
I am trying to grind some really bad welds and am useing a 4 1/2 inch grinder. Problem is that it will take too much off and they are in a tight spot. Can anyone suggest a type of smaller or better grinder for finishing off the weld..
Thanks
Post Fiend
Joined: Oct 2003
Posts: 6,214
Likes: 13
From: New Jersey
Air powered die grinder (get a straight one, and a right angled one) with 2" sanding disks with the "screw on" type backing plate/shaft. Very easy to replace the sanding disks and if you buy them in bulk (like, 100 at a time mail order), each disk is about 70 cents or thereabouts. I generally use 80 grit as it can remove reasonable amounts of material without too much pressure, and you can still control with touch how much is removed. With 40 grit it's very easy to go past the bead and into the material, and 120 grit just takes to darn long.
Also with your 4-1/2" grinder, instead of grinding disks or cutting disks, consider zirconia flap disks. They look like a slightly cupped wheel with little pieces of sandpaper glued around the perimeter. These things last significantly longer than grinding wheels and also come in many different grits. $5 with tax at home depot and/or lowes. I use them for wood, steel, iron, aluminum, and so on. Grinding disks even at a buck for two disappear too quickly. You just can't use the edge to cut... they disintegrate quickly. That's why I bought a second 4-1/2" grinder - one I keep an 80 grit flap wheel in, the other I keep metal cutting disks in.
Also with your 4-1/2" grinder, instead of grinding disks or cutting disks, consider zirconia flap disks. They look like a slightly cupped wheel with little pieces of sandpaper glued around the perimeter. These things last significantly longer than grinding wheels and also come in many different grits. $5 with tax at home depot and/or lowes. I use them for wood, steel, iron, aluminum, and so on. Grinding disks even at a buck for two disappear too quickly. You just can't use the edge to cut... they disintegrate quickly. That's why I bought a second 4-1/2" grinder - one I keep an 80 grit flap wheel in, the other I keep metal cutting disks in.
Post Fiend
Joined: Oct 2003
Posts: 6,214
Likes: 13
From: New Jersey
Sure, happy to help. A friend of mine turned me onto the 2" sanding dics (and associated backing/rod thing) after seeing me grind beads off with a dremel, a 36" extension, and a carbide cutter for the tight places. He laughed, dragged my sorry butt to Lowes, and showed me the "easy way". Sometimes even a small air powered die grinder doesn't fit, and in those cases I just wedge a screwdriver in there to chip off the slag and the little "mig *****" and leave the rest of the bead. My welding has gotten to the point where even though it's often ugly, the bead is always *in* the material rather than sitting on top, thus less grinding in general. Took me a while to be less timid with the heat control. Now I weld almost everything on "full blast, burn holes in everything" setting, and use wire speed and hand speed to control the weld puddle.
Thread Starter
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Laughing Gas
Joined: Jul 2004
Posts: 769
Likes: 3
I am just starting out welding and had my first nightmare with my 67 Fairlanes battery apron area. I blew right through man i got nervous it is in a high visible area. Well I figured out how to bridge a weld over a hole. It isnt perfect but better than the big hole. I turned the heat down a bit and slowed the wire and that seemed to help even though I am not real sure if thats the right procedure..LOL. I just hit it quick with tack welds to bridge over.I just got a Hobart 140 and am using the gas also. The problem is that someone before I had the car really welded the crap out of the battery apron replacement with a ton of weld. So cleaning them off is tough but now should be easier with the setup you suggested.. I got a die grinder but went to the popular auction site for some 2in 3m R roloc grinding discs with 2 mandrels.. They were 1.35 a disc at my local supply shop and another 10.00 for 1 mandrel..
I got 2 mandrels and 50 discs for 30.00 shipping included.. Thanks for the tip ended up being much less than 70 cents per disc... Thanks again..
I got 2 mandrels and 50 discs for 30.00 shipping included.. Thanks for the tip ended up being much less than 70 cents per disc... Thanks again..
Post Fiend
Joined: Oct 2003
Posts: 6,214
Likes: 13
From: New Jersey
Practice makes perfect.
Take your truck for a ride on "trash night" and go through your town and look for "garbage" made of steel. Weight benches can be found with round or square tubing, for example. Metal bracketry, steel shelves, and so on. Toss some of it in your truck, cart it home, and hack it up into manageable pieces (sawzall!). The grind bevels on the edges, and weld them together. Start off welding similar thickness materials together, doing a butt-weld. Once you get the hang of that, and write down the settings of your welder, try angled weld's fillets, thicker materials, and so on, writing the settings down for each thickness material.
That's how I learned. I'd rather ruin a hacked up weight bench I took from the curb than something important to me. Trust me, the first time I got my mig welder I thought to myself "how hard can this be?" and I wasted a ton of steel tubing trying to make a roll cage. Bad idea!
Take your truck for a ride on "trash night" and go through your town and look for "garbage" made of steel. Weight benches can be found with round or square tubing, for example. Metal bracketry, steel shelves, and so on. Toss some of it in your truck, cart it home, and hack it up into manageable pieces (sawzall!). The grind bevels on the edges, and weld them together. Start off welding similar thickness materials together, doing a butt-weld. Once you get the hang of that, and write down the settings of your welder, try angled weld's fillets, thicker materials, and so on, writing the settings down for each thickness material.
That's how I learned. I'd rather ruin a hacked up weight bench I took from the curb than something important to me. Trust me, the first time I got my mig welder I thought to myself "how hard can this be?" and I wasted a ton of steel tubing trying to make a roll cage. Bad idea!
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