Re: 4 1/2\" angle grinder
I have a one man shop. At any given moment I'll have four to six four and a half inch angle grinders.
The best to buy in my humble opinion is Metabo. They have a wrenchless change out system and they just seem to want to wear forever.
Right now I have a couple of Metabos, a dewalt, a milwaulkee, and a hilti.
The hilti costs as much as the metabo and I can see where it would be great for concrete work but it isn't really that great for ironwork. It's just awkward for me the way they've angled the head.
The milwaulkees just don't seem to wear for very long. But I do like their paddle handle over the other brands.
I've had dewalts that were good and some that were fair. Two notes on them. First and foremost is Home Depot carries two models. The cheaper one is for those who want an angle grinder and don't plan on using it. The more expensive one lives longer than the milwaulkee and is lighter and has a smaller head for getting into smaller places. But do check out the model numbers and make sure you're getting the heavier duty one if you're planning on using it. Otherwise you can save your money and run to Harbor Freight and spend a third the money for real trash.
I had a dewalt that took forever to wear out. This was not good. A bud had been using it and working at my shop and complaining about the safety tab. He was fighting it. So I let him remove it in a moment of almost fatal head up buttitis.
That grinder bit me more times than I can count. I have found the dewalts the best for cup brushes. I use cup brushes all day long. And take it from a scarred up old man, don't mess with the safety tab on the paddle switches.
If I was going to buy one angle grinder I'd look at what I'm doing with it. A lot of the good ones don't have variable speeds and they aren't that compact around the head. Also a wrenchless changing system is one of the handiest things to come down the pike since pockets on pants.
Variable speeds and a paddle on off switch is the cat's meow for cup brushing, polishing, and some grinding, detail kinds of work. But if you're just grinding and it's all about metal removal then those options aren't really important.
I do artsy fartsy with iron, wood, and rock. There are stones available for using on granite, bits that work like a chainsaw on wood and then your whole spectrum of blades for metal work.
The flap discs are the greatest things since syrup on pancakes for working metal. You can lean into the work and they remove metal as good as a regular metal disc without the same size of sparks. Then you can lighten the pressure you're applying and polish like you'd do with a sanding disc.
My welding supplier has a new metal disc that has three notches cut in the perimeter. What's so trick about it is you can see exactly what you're doing as you're doing it. It blows the mind to watch the metal go away as you're working it. The downside on these discs is their cost.
Probably the biggest mistake rookies make with angle grinders is also the most expensive. They're not aware that those sparks permanently scar paint and glass even at a distance. A wayward group of sparks across the paint job of the wife's car can be one of the most costly mistakes modern man can make.