Help me with grinding

[Greg Di]

This may sound stupid, but I own three grinders and I admit that I really don't know how to use them properly to get the desired results. What I mean is that no one ever showed me or told me what kind of attachment to use for what.

Situation 1: Getting ready to weld. I need to clean up the metal to be welded (remove rust or contamination) and get to shiny steel. Also need a place to clamp the ground.

Situation 2: The weld is done, but I want to remove slag and clean up the weld.

Situation 3: I want to make the weld disappear after I'm done. Maybe it's a patch or a splice and I need to blend the two pieces together.

Situation 4: Prep for paint. I need to make everything smooth.

[84ZMike]

This is a quick down and dirty and with use you will find you can use the flap disk for it all but with more $ so my advise is to get several different ones and keep you grinders loaded with a different wheel....don't forget wire wheels they work best for slag removal etc....


Traditional stone type wheel 24 grit = heavy removal can use light pressure for appearance

Flap disk grits from 24-120 (I use the 60 and 80 mostly) = light stock removal and feathered edges for blending in repairs and "slices"

Scotch brite type = polishing / final prep. for paint

[k.a.m]

I wont post mine mike yours sounds alot less complicated than what i just typed, I was going to add if he did not already have a face shield invest in one plus glasses, I use both.

[Hotfoot]

Ditto on Flap Disc. I use #40's for prep and clean-up, and 60's after to "blend" they leave a nice finish....grease or paint will clog up a disc very fat, making it useless. I use a knotted wire brush on really rusty stuff before the flapper, to save discs...I go though too many of them as it is!!

[Skwerly]

Yes, the flap discs work wonders and are relatively cheap, but sometimes for general surface cleanup I use a wire-wheel attachment on my regular old drill. Either way works well!

I use this kind:

http://www.usahardware.com/inet/shop...rill/76411.htm

[villemur]

For prepping metal to be welded I just started using Strip-It type disks. They look look a bunch of strings coated with abrasive and then molded into a disk. They are a little expensive, but man, do they ever do a nice job and they're very fast. Make sure to only use them on flat, smooth surfaces, because if you catch a sharp edge with them you'll wear them down in seconds. Here's a link to some: http://www.lehighvalleyabrasives.com...n-Clean/Detail

For removing slag on welds that are too purty to grind down I just use a wire wheel.

For when more metal needs to be removed I use flap disks. For when a lot of metal needs to be removed I use a grinding wheel.

[enlpck]

Hard wheels: rapid removal of metal or rust, good for profiling, make a mess. They can put a fair bit of heat into a workpiece. Cheap. Don't bear too hard. They won't cut any faster. ou can excavate with the edge.

Cutoff wheels: For, believe it or not, cutting. Also useful for grooving material. Come in a variety of thicknesses, 0.045 and 0.060 being real common. They don't take a lot of side force, an throw chunks when they break, The chunks are sharp and moving fast and will penetrate flesh. Use a gaurd. Keep these in line with the cut, as ANY significant side load will cause failure. Material up to about 1" diameter: just cut through it. Cutting sheet it is best to take several passes, grooving deeper each time, as trying to do this in one shot will allow the edge of the material to disintegrate the wheel. If the material (or wheel) gets too hot, the wheel will disintegrate.

'Elastic' cutoff/grinding wheels: A variety of manufacturers make wheels that are usable for cutoff or grinding Pferd is that brand I like. They take side load better than regular cutoff wheels, but arn't great for grinding and will break. They are my preference for cutoff work unless I need a narrow kerf, as they are less likely to shatter. Available from about 0.060" to 0.250" thck, the thinner ones being intended primarily for cutoff work.

Flap wheels (Tiger wheels): The cat's @ss for smoothing and polishing. 40grit for reasonable metal removal, up to 120 grit for not-quite-mirror smooth. decent life, but not real high removal rates. Takes practice to avoid making a noticeably wavy surface, as they are soft. Good genera purpose cleaning and light polishing. Not very heat tolerant in most makes.

Wire wheels: Great for slag removal, paint removal, derusting, preweld prep (except soft metals like aluminum, where they tend to bury the crud in the surface). I always keep one in hand when stick welding. Don't force them. Lighter pressure and more passes in more effective than heavy passes. Vary the direction. They throw wires out at 8 billion miles per hour, so safety glasses and face shield, and no exposed skin. Leather recommended. Keep the wires perpendicular to the surface or they fly out more. I prefer the radial type to the cup type for most things.

I tend to keep a couple different setups handy, a wire wheel and hard wheel always, and a flap wheel usually.

[Diamond]

I use a 1/4 inch grinding wheel to take a weld down and a 36 grit soft pad to smooth and make it look nice. Just make sure you grind in the right direction so you dont dig into the metal. Grinding with the grain makes it dig deeper fast than if you go across it. Soft pads you can get at Wall Mart and I think there cheaper then flap wheel you just have to buy an adaptor for your grinder to use them. If you get soft pads keep them out of any moister or they will rip apart and shorten the life span of them.

[weldgault]

An answerto all: use A36P disc. John ( not A24R)

[Broccoli1]

This may sound stupid, but I own three grinders and I admit that I really don't know how to use them properly to get the desired results. What I mean is that no one ever showed me or told me what kind of attachment to use for what.

Situation 1: Getting ready to weld. I need to clean up the metal to be welded (remove rust or contamination) and get to shiny steel. Also need a place to clamp the ground.

Situation 2: The weld is done, but I want to remove slag and clean up the weld.

Situation 3: I want to make the weld disappear after I'm done. Maybe it's a patch or a splice and I need to blend the two pieces together.

Situation 4: Prep for paint. I need to make everything smooth.

You're short one grinder

[John Stuckey]

Another caution about wearing safety glasses and face shields while grinding!!
I had a customer this past year, young guy 20/20 vision before he got a piece of wire stuck in his eye. He had safety glasses on - no shield and the wire went between the glasses and his cheek into his eye. While the surgeons were able to save his eye he became an instant cataract patient and Rx eye glass customer for me. I can do without that kind of business
John
Optical store owner

[Gaze]

Another caution about wearing safety glasses and face shields while grinding!!
I had a customer this past year, young guy 20/20 vision before he got a piece of wire stuck in his eye. He had safety glasses on - no shield and the wire went between the glasses and his cheek into his eye. While the surgeons were able to save his eye he became an instant cataract patient and Rx eye glass customer for me.

Happened to me, too. Not as drastic...small hot bit got up past my shield and melted itself onto my eyeball surface. That's three rust rings for me Each time it took a doc to get it out and each time they commented on the previous ones they see in the scope. Think my eyeballs are magnetized.

[Rocky D]

Man, you guys sure love those flap disks...I gotta go against the grain here, cause I found they're just too expensive, and hard to control for precision metal removal. With the flap disk, if you use them to remove paint or rust, you waste them very quickly. They are hard to control when removing welds from corners on square tubing, and bringing the weld to a flat,...they always seem to leave a ripple where the weld was. Now, what I use is sanding disks with a semi-flexible backing...if you run over paint, and rust enough to clog the disk, ya change it out for only pennies, compared to dollars on a flap disk. You can remove a weld quickly and flat in a few strokes, and for aluminum, (you'd waste a flap disk) the disk with a little dry lube on it will cut aluminum all day and fast. Once you get used to the sanding disk, you won't go back to the flap disk...cheaper, too. Trust me, I've done the research.

[pfatz]

I always wore safety glasses when working around welding and grinding including under my hood. In my shop where I had 120 people working, everyone put them on (as part of the safety equipment) before entering the workplace and wore them until out of the shop. Despite this I was the one who got a piece of steel in my eye which I only realized when I saw rust while shaving one day. It required a visit to my eye DR to take it out. The only other injuries in 20 years was a welder rolled a large H beam over onto his foot. Missed the safety shoe toe. Broke the foot. Failure of safety training was my thought. He had been warned not to do that. I burned my hand due to worn out gloves twice. You'd think I would learn since it is painful.

Wear safety glasses and even goggles are good around grinding.

EdH

[lcats]

Rocky- What specific sanding disks do you use? Are they the peel and stick kind? Can you use a DA sander? i have been using an angle grinder (4") to remove practice welds, but i will be cutting some square tube (45's) and would like to sand the welds flat.

Thanks,

Luke