Which grinder disks do I need?

[jrcampbe]

Hey guys,

I'm teaching myself to weld. I took a night class at the local tech school which was ok, but nothing spectacular. I did get me exposed to all the processes, but not with much depth

I bought a Miller 211 in one of the last Zoro sales. It's pretty simple and I'm ready to do some projects with it.

What I really want to learn is TIG, and because my garage needed a proper torch anyway, I bought a oxy-acetylene rig with a Smith AW1A airliner welding torch. I've been practicing OA welding as a way to get the skills for TIG, but I find that I really enjoy the OA process. I can see why artists and others not terribly concerned with speed like this.

Anyhow, I'm about to move from little practice coupons to some real projects and I don't know what I should do for grinder wheels. Thanks to this forum, I got the great deal on the Metabo 4 1/2" grinder, but I haven't bought any consumables for it.

Can anyone make a recommendation for me? I need to be able to clean metal, cut or grind for fit up, and then grind my novice welds into something that doesn't look horrible.

I'm working with mild steel, though one project I want to tackle shortly is a stainless table frame for a kitchen table with 8-foot Ikea butcher's block counter top. I know I need different gas for that unless I torch weld it, in which case I need flux. No idea if I would need different grinder wheels.

Thanks for the advice!!!

Jim

 

[MrGiggles]

I don't have any complaints with harbor freight wheels. They seem to be as good as any of the entry level brands.

On the thin 7" HF disks that I use, if they catch, the centers break out instead of blowing into pieces. Might be an unintended bonus of cheap disks.

 

[jrcampbe]

I guess what I'm asking is what kind to get, rather than what brand. I don't know anything about grinders. I don't know a "flap disk" from a flapjack.

Also, I got a little pneumatic die grinder as a free package when I bought my big impact wrench. I've never used it. Is it something that would be useful on welding projects? Again, if so, with what attachments?

 

[FMC]

grinding discs to me are like a thinner version of a grinding wheel, sanding discs come in a wide range of grits, 24, 36, 50, 100 etc, i always liked 36 grits not too coarse but last well, prime importance is a good backing pad and run 2 discs at a time to stop then digging

 

[txvwnut]

If I'm needing to grind a bevel for a fillet I'll use a hard stone rated for whatever metal I'm grinding, if I'm just dressing for a corner or **** weld I prefer a flap disc. I also prefer the flap disc for when I have a need to dress the weld down for when I don't want it seen.

 

[MrGiggles]

I guess what I'm asking is what kind to get, rather than what brand. I don't know anything about grinders. I don't know a "flap disk" from a flapjack.

Also, I got a little pneumatic die grinder as a free package when I bought my big impact wrench. I've never used it. Is it something that would be useful on welding projects? Again, if so, with what attachments?

Grinding wheels are considerably thicker, for removing material, grinding welds, etc.

Cutting wheels are thinner and for cutting through steel.

Flap wheels are for sanding/polishing. I've read that the coarse ones work as good as a grinding wheel, but I haven't used them to confirm.

I have three die grinders. They are nice for confined areas where you can't fit an electric grinder. One is a 90* with a roloc adapter, one wears grinding stones or a wire brush, and the other is for cutting wheels. You need a lot of air to run them efficiently.

I would start with a few grinding wheels and cutting disks, and a few flap wheels in various grits. A wire brush for the die grinder is very handy as well, saves a lot of work.

 

[Bobcat753]

Here is some useful info.

This is a 4 1/2" Grinding Wheel, Best thickness is 1/4". These are used for heavy metal removal.

This is a Flap Disc. This is used for light to medium metal removal. These are also good for removing coatings on metal(rust,mill scale)

This is a Cutting Disc. This is used for cutting steel. Best thickness is 1/8".

This is a Wire Wheel. This is used for removing paint,rust or other coatings on metal. These will shoot off the wires and are dangerous.

Finally these are Wire Cup Wheels. These are similar in use as above but are good for removing coatings on large pieces of flat steel.

One other mention is these paint stripping discs. They work wonders with removing paint from metal.

For a Specific brand I use 3M but I'm a professional welder. Dewalt makes some good wheels at reasonable prices.

 

[md21722]

I don't want to derail your tread, but based on your question, I do want to pass on some often overlooking personal protective suggestions. Wear a respirator, safety glasses AND a full face shield. Cutting is very dirty work, and chunks of metal or cutting disc can get around your safety glasses and into your eye and even lodge right into your eyeball. I've had good luck with the Diablo cutoff wheels from Home Depot. Others think they are too expensive. Norton and 3M make excellent abrasives. Check out Lehigh Abrasives online store.

Bobcat and I were typing at the same time.

 

[Loscaldazar]

Why are flap discs for light metal removal? They remove metal faster than grinding discs do. Unless you are gouging with the edge of the disc (which is impossible on a flap disc), flap discs are superior, albeit more expensive and wear out quicker.

Flap discs are unbelievably faster than grinding stones. Skip to 2:50 to see a flap disc vs sanding disc vs grinding stone

https://www.youtube.com/watch?t=194&v=svB1iq4yRCE

Several other companies have put out videos like that (diablo being another). I can verify from my own testing that a coarse grinding disc removes metal at about the same rate as a 80 or 100 Grit flap disc. A 36 or 48 grit flap disc is way quicker.

If you buy the ceramic (red) flap discs from http://www.lehighvalleyabrasives.com/ they are fairly cheap and last much longer than zirconia aluminum ones, plus they cut faster than an equal grit. A 40 Ceramic flap disc is roughly equivalent to 24 grit zirconia aluminum flap disc, but it's lifespan is MANY MANY times longer (a 24 grit zirconia lasted me less than 4 minutes of grinding, the 40 grit ceramic was still going after a good 20 minutes of grinding, and had much more left in it). The $1 or so premium for the ceramic is worth it.

Get a few different grits on flap discs and you can do everything from heavy metal removal (40/60 grit ceramic) to polishing (80-100/120 grit ceramic). For someone who is welding at home, the cost of the flap discs versus the stones is not a bad cost. Even for professionals, it can take a while to wear out some of the Lee High Valley. It took Chucke2009 (welds for his day job as well as for youtube) a month or two to completely wear out his first Lee High Valley flap discs, and that was a 40 or 60 grit zirconia (the ceramic will have even longer life). So you can get some good life out of them assuming you aren't beveling a 6' diameter pipe for welding.

I had this question a while ago too, and here where the answers I got http://www.garagejournal.com/forum/showthread.php?t=296956

 

[Bobcat753]

I don't want to derail your tread, but based on your question, I do want to pass on some often overlooking personal protective suggestions. Wear a respirator, safety glasses AND a full face shield. Cutting is very dirty work, and chunks of metal or cutting disc can get around your safety glasses and into your eye and even lodge right into your eyeball. I've had good luck with the Diablo cutoff wheels from Home Depot. Others think they are too expensive. Norton and 3M make excellent abrasives. Check out Lehigh Abrasives online store.

Bobcat and I were typing at the same time.

Lol, And yes PPE is a MUST. I always wear at least Z87 safety glasses. Most of the time I use my Flip Front welding hood. +1 on Lehigh Valley Abrasives. Excellent prices when ordering in bulk.

 

[MJD1]

For the stainless you will want cutting discs for stainless, and if using the hard grinding wheels , the same. The stainless wheels usually are a little slower cutting, but last longer. Regarding cutting discs, go with the thin .045 ones. 1/8" thick were mentioned, but that is a poor choice, since you are removing more metal than needed. This is slower, builds more heat and is harder on the grinder. Norton, sait, CGW and pearl are good brands. As for flap discs, zirconia is a good choice for steel and stainless steel. I use 40 grit, and if a finer finish is needed, a disc that has been worn down works pretty well.

 

[md21722]

Why are flap discs for light metal removal? They remove metal faster than grinding discs do. Unless you are gouging with the edge of the disc (which is impossible on a flap disc), flap discs are superior, albeit more expensive and wear out quicker.

It really depends on what you're doing. Here are some examples:

"I think grinding wheels last longer, remove material faster, and leave a rougher finish. Flap disks can be bought with a finer grit to leave an almost polished finish. Flap disks also have a little bit of "give" so they'll leave more of a molded or rounded surface when rounding off edges, whereas a grinding wheel, you'll see every single time you changed the angle. On the other hand, when it comes to removing rust or other heavy coating, flap disks will fill up and stop working nearly as well, whereas a grinding wheel will keep going."

"I think the difference in opinions stems from the work done. We do shipyard type work, fitting and structural stuff. It's all very rough. Y will never see a flap disc in a shipyard. We are about speed and grinding on hot steel. Finish doesn't matter, the sand blasting will take care of that."

"Flap discs are expensive and they burn up when you use them on hot steel."


So you might as well try the flap discs and if you run into problems go with the stone.

 

[lightning02]

If I had any sort of grinding disk come part in away what so ever I'd be shoving it up someone's ***. That's just crazy thinking

Anyways... I use Norton for cutting and iv been very pleased with them. Never has one failed on me or not done there job.

 

[ovrrdrive]

The hard discs remove metal a little faster but with a lot less control and more collateral damage. The flap wheels are a little slower but give you much more control because they have a soft face. You need some of both. I like the 36 grit flappers from HF and IMO the hard discs are all the same. For removing mill the hard discs are the only way to go. I usually knock it off with a hard and then finish with a flapper to give me a smooth finish to weld on. You can weld through mill but you get a much nicer bead if its taken off. If I have a small weld to clean up I go right to the flapper. If I had trouble getting a bead and have a glob to take off I use a hard to get it down then switch to a flapper to finish it up. Unless it's a finished part that needs to look factory I don't grind the weld flat because it takes off all the strength out of the weld. A nice bead is something to be marveled anyway.

 

[BD1]

I don't want to derail your tread, but based on your question, I do want to pass on some often overlooking personal protective suggestions. Wear a respirator, safety glasses AND a full face shield. Cutting is very dirty work, and chunks of metal or cutting disc can get around your safety glasses and into your eye and even lodge right into your eyeball. I've had good luck with the Diablo cutoff wheels from Home Depot. Others think they are too expensive. Norton and 3M make excellent abrasives. Check out Lehigh Abrasives online store.

I would add a leather apron to the list. Even the cheap
hf one is better then nothing. A quality one with lifetime warranty will be a $160.00 but money well spent. made in USA too.

https://www.moonshineleather.com/productdetails.cfm?productcode=A06A-HCPL

 

[Mohawk Dave]

DO NOT BUY HF STUFF.

Get good flap discs. You'll use them more than anything. A couple death wheels (cut off wheels, usually 1/8") will last you a while.

Different wire wheels are good to have, from straight to knotted. The cups are much more efficient on a 7/9" grinder, but still good to have for a 4.5".

Whenever you see a good deal on quality flap discs, buy as many as you can afford. They are not cheap and if you start fabbing a lot, they are your best friend.

Roark abrasives is a good website with good products and about as cheap as they come at full price.

I can't remember the last time I used or wanted to use a grinding wheel for hobby. That's more like big tractor buckets, I Beams for bridges etc, taking out big chunks for something like a T-Intersection or a fillet. (Cross that stuff when you get there)

 

[Superbec]

Ok.. so I didn't read all the blatter.

What you need.

2x angle grinders

one will always have cut-off wheels on it, (1mm discs, get the ones for stainless they lasta a bit longer)
the second one you use for grinding&beveling &fitting with a grind stone (like the cutoff disck only mutch thicker), or flap disck orwhatever you need.


you need 2 because changing from cut-off to grinding disck will get old pretty fast, a weldor should always have at least 2 grinders


p.s. the cutting grinder remains as from factory with the guard on ! don't be that guy with your eye in the pocket), on the other hand the grinding "grinder" can have the guard off because it's used in different positions, still mind where the sparks land.

 

[bcradio]

I don't want to derail your tread, but based on your question, I do want to pass on some often overlooking personal protective suggestions. Wear a respirator, safety glasses AND a full face shield. Cutting is very dirty work, and chunks of metal or cutting disc can get around your safety glasses and into your eye and even lodge right into your eyeball. I've had good luck with the Diablo cutoff wheels from Home Depot. Others think they are too expensive. Norton and 3M make excellent abrasives. Check out Lehigh Abrasives online store.

Bobcat and I were typing at the same time.

And yet others think they are too thin and shatter too easily. I myself prefer a slightly thicker cutoff wheel (like DeWalts .045 wheels) because the last longer and are much less likely to shatter on you.

Food for thought.

 

[bcradio]

Why are flap discs for light metal removal? They remove metal faster than grinding discs do. Unless you are gouging with the edge of the disc (which is impossible on a flap disc), flap discs are superior, albeit more expensive and wear out quicker.

You answered your own question.

If I am in a race to the finish I'll use a flap disc for removing large amounts of material, but I almost never am so I use a grinding wheel and finish it up with a flap disc.

 

[tarbellb]

To reiterate a few good and bad points that have been said here:

_Seems you can afford and want nicer equipment so AVOID HF disc of all kinds. Period.

_Flap disc are superior in every way to standard grinding disc.

_If cutting material use .045" quality disc, anything thicker is wasted time/effort.

_Wire cups and brushes are excellent but extremely dangerous, use caution.

Look at Lee Valley Abrasives for good quality and prices. My personal favorite is Pferd (german). You will find higher quality abrasives not only work better, but last longer, resulting in a higher value money wise.

 

[crewchief888]

personally i havent had any issues with abrasives that any of the big box stores sell.
i get most of mine from HD, when they go on sale or clearance, i buy a few

in an "emergency" i bought some cutoff disks from HF, definitely not worth the savings....

ive had real good life from the dewalt cup brushes

i dont use many flap disks, but, i probably will as i run out of the single disks i have stocked up.

i use the thicker (.045 ?) 4 1/2" cutoff wheels, they do last a little longer than the thinner ones for me.

 

[Fixed]

I would buy a variety, and find out what products you prefer for different tasks. I personally love flap discs, but use grinding wheels for heavy stock removal.

The thin Walter zip-cut cut-off discs are excellent, but expensive.I just bought a 10pk of the Dewalt ones, so I'll see how they compare.

 

[md21722]

I don't want to derail your tread, but based on your question, I do want to pass on some often overlooking personal protective suggestions. Wear a respirator, safety glasses AND a full face shield. Cutting is very dirty work, and chunks of metal or cutting disc can get around your safety glasses and into your eye and even lodge right into your eyeball. I've had good luck with the Diablo cutoff wheels from Home Depot. Others think they are too expensive. Norton and 3M make excellent abrasives. Check out Lehigh Abrasives online store.

I would add a leather apron to the list. Even the cheap
hf one is better then nothing. A quality one with lifetime warranty will be a $160.00 but money well spent. made in USA too.

https://www.moonshineleather.com/productdetails.cfm?productcode=A06A-HCPL

Come to think of it, I use a welding jacket when using the angle grinders. I've got burn holes in other clothing. And you can google online and see pictures of folks who have set their pants on fire.

 

[md21722]

If I had any sort of grinding disk come part in away what so ever I'd be shoving it up someone's ***. That's just crazy thinking

Anyways... I use Norton for cutting and iv been very pleased with them. Never has one failed on me or not done there job.

The OP mentioned cutting and grinding. I've had Forney cutting wheels come apart on me.

 

[tekgmr]

I would say that pretty much any brand is fine as far as grinding, cutting, or sanding disc go. I've never found one that was considerably more impressive than any other. You should also remember that your small air grinder is just a smaller version of your big electric one. Just use common sense and you know when to use one over the other. And the best tip I can give you is do lots of practice making your welds look nice. How a weld looks is an indicator of what you're doing right and what you're doing wrong. If you have to grind a weld down then there's something wrong. Grinding a weld makes you a grinder not a welder.

Sent from my Z970 using Tapatalk

 

[FMC]

I would say that pretty much any brand is fine as far as grinding, cutting, or sanding disc go. I've never found one that was considerably more impressive than any other. You should also remember that your small air grinder is just a smaller version of your big electric one. Just use common sense and you know when to use one over the other. And the best tip I can give you is do lots of practice making your welds look nice. How a weld looks is an indicator of what you're doing right and what you're doing wrong. If you have to grind a weld down then there's something wrong. Grinding a weld makes you a grinder not a welder.

Sent from my Z970 using Tapatalk

if your building battleships and oil tanks perhaps so, to say grinding a weld makes you a grinder is just not true... it makes you a finisher lol

 

[2oolhound]

I like the 1/16" cut off discs. You have to be careful to hold them precisely but they cut fast and clean. Like many others I have 1/2 doz 4.5" grinders. 40 grit flap, finer flap, 1/4" grinding disc, cut off wheel, wire cup and usually a 2nd 1/16" zip disc as they wear out fast. A lot less time is spent changing discs during a job this way. Hard discs give more precision while flap discs are great for removing rust, mill scale, paint and powder coat. Doing repair work and also using a lot of recycled steel, I deal with all these surface conditions.

Also pay attention to the recessed discs as opposed to plain flat ones so you can hold the face on a flat surface and cut or grind even to the surface without the lock ring or arbor nut from contacting the surface 1st.

If I have lots of cutting or grinding to do I use a 7" grinder.

 

[brownsmustang]

3m all the way! Lol we make the 3m flap discs here at the plant.

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[lightning02]

The OP mentioned cutting and grinding. I've had Forney cutting wheels come apart on me.

i have used makita discs for grinding things over the years and again never had a problem. served me well.

as for as the broken thing. i was referring to the poster that said the HF cutting disc are designed to break for the persons safety or something like that he said. not sure id stand around that person when hes using a grinder

 

[taumac]

I've used stuff from HF and found to burn up cutting wheels and flap wheels quickly but grinding wheels seem to work ok. I switch to Norton or Diablo cutting and flaps wheels I get from HD. I use knotted wheels to clean surfaces or flap wheel. I grind my welds with grinding wheels and do final dressing with flap wheels or sanding disc.

 

[ZRX61]

If you're going to end up using wire wheels it is imperative that you buy either a leather apron or armored underwear. I've only been stuck 3 times by flying wire.
1, Stapled my **** to my leg
2, Stapled my ballsack to my leg
3, Stapled my **** to my *********.

It is also VITAL that you have pliers VERY close to where you are using the wirewheel so you don't have to hobble 15-20ft to the ******** toolbox to grab pliers to remove the wire that is making you walk funny.

 

[taumac]

If you're going to end up using wire wheels it is imperative that you buy either a leather apron or armored underwear. I've only been stuck 3 times by flying wire.
1, Stapled my **** to my leg
2, Stapled my ballsack to my leg
3, Stapled my **** to my *********.

It is also VITAL that you have pliers VERY close to where you are using the wirewheel so you don't have to hobble 15-20ft to the ******** toolbox to grab pliers to remove the wire that is making you walk funny.

Ouch, Ouch, F@CKING Ouch!!! I have 2 knotted wheels. A flat and a cupped. The flat I use with the guard but cupped I can't. After your post maybe I make a special guard to for the cupped one.

 

[ovrrdrive]

If you're going to end up using wire wheels it is imperative that you buy either a leather apron or armored underwear. I've only been stuck 3 times by flying wire.
1, Stapled my **** to my leg
2, Stapled my ballsack to my leg
3, Stapled my **** to my *********.

It is also VITAL that you have pliers VERY close to where you are using the wirewheel so you don't have to hobble 15-20ft to the ******** toolbox to grab pliers to remove the wire that is making you walk funny.

You either have a huge **** or are an excellent shot... Either way you should get Murphy's law tattooed on your forehead. lol

 

[PT Doc]

Ceramic flap for durability.

 

[trevdawg]

This is helpful


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[ChevyEFI]

I had a small chunk out of the outer edge of a HF wheel and I wanted to get something done instead of wasting time.
Ordered United Abrasives/SAIT 21020 4-1/2 by 1/4 by 7/8 A24N Type 28 Grinding Wheel, 25-Pack. off of youknowwhere.
They wear much quicker an take off material much quicker than the HF wheels. And just a bit over a buck a piece.
If your time is worth anything, an upgrade in grinding wheels is probably worth it.

 

[ZRX61]

You either have a huge **** or are an excellent shot... Either way you should get Murphy's law tattooed on your forehead. lol

I learned to stand to one side of the wheel (all 3 were with a wheel on a bench grinder). At least I learned to put pliers by the grinder the first time so only had to hobble to the toolbox once.

 

[trevdawg]

Good info


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