Is the Ryobi P421 angle grinder any good?

[BikeRider]

I've never owned or used an angle grinder and have put off buying one till now. The main use I'd have for one is removing tough rust from complexly-shaped structural auto parts, e.g. control arms, brake calipers, suspension springs, manifolds, etc. I've been restoring a 29 year old car and working on some other older cars, each with plenty of rust, and so far I've been using a combination of power drills and an impact driver with wire brush, abrasive and grinder wheels, a rotary tool for hard to reach spots, and a scraper and set of picks.

It's worked pretty well but it's a really slow and laborious process, and the vibrations really mess up my hands for weeks afterwards, with a kind of peripheral neuropathy setting in that makes it hard to fall and stay asleep. It's probably not that great for these tools either, as they're not really meant to do this sort of thing on an extended basis. There's still a fair amount of rust removal work to be done, so I'm thinking of getting a cordless angle grinder to make it easier and safer this time. It has to be cordless as I work on my car on the street and there's no easy way to get an extension cord there.

Since my needs aren't too advanced, I don't anticipate doing much grinding or cutting beyond the occasional stuck bolt or stud, and once I'm done restoring and fixing these cars the grinder will probably stay in its bag most of the time, I thought I'd go with a decent lower-end model, and the one that caught my eye was the Ryobi P421, which is on sale right now at Home Depot as part of a promo deal where I can get the tool, 2 4Ah LiOn batteries, and a charger, for $100. Seems like a decent deal. But it's their most basic cordless grinder that normally sells for around $45 and is not brushless. They have 2 more expensive models that are both brushless, smaller, lighter, and run much faster, like nearly twice as fast (~10,000rpm vs. ~6000rpm).

RYOBI ONE+ 18V Cordless 4-1/2 in. Angle Grinder (Tool-Only) P421 - The Home Depot

RYOBI introduces the 18V ONE+ Cordless 4-1/2 in. Angle Grinder (Tool-Only). The ONE+ 4-1/2 in. Angle Grinder offers cordless convenience and the power of 6500 RPM for fast and precise work. This tool offers a host of user-friendly features, such as onboard wrench storage, the comfortable...

www.homedepot.com

RYOBI ONE+ 18V Brushless Cordless 4-1/2 in. Angle Grinder Kit with (1) 1.5 Ah Battery and Charger P423KN

RYOBI introduces the 18V ONE+ Cordless Brushless 4-1/2 in. Cut-Off Tool/Angle Grinder Kit with 1.5 Ah Battery and Charger. The brushless motor in the 4-1/2 in. Angle Grinder provides longer runtime, more

www.homedepot.com

RYOBI ONE+ HP 18V Brushless Cordless 4-1/ 2 in. Angle Grinder Kit with (1) 4.0 Ah Battery and Charger-PBLAG01K - The Home Depot

The RYOBI 18V ONE+ HP Brushless line of products is redefining power and performance. The RYOBI 18V ONE+ HP Brushless 4-1/2 in. Angle Grinder/Cut-Off Tool (PBLAG01B) provides up to 30% faster cutting and also provides up to 9,200 RPM to help complete your next project more efficiently and...

www.homedepot.com

So I'm wondering, for my needs, is the P421 ok, or would I be best served going with one of the brushless models, or perhaps going with a different brand entirely? I can afford a somewhat nicer grinder, it's just that I don't know that I can justify it for my needs. So I guess I'm asking if for all its limitations the P421 is still a decent grinder, and perfectly fine for the occasional weekend mechanic like me?

 

[American Locomotive]

I can tell you that the P423 (the mid-tier brushless one) is really pretty marginal, and about the weakest I'd consider to be "acceptable" for an angle grinder.

 

[KenB]

I have the P421 and it’s OK for small, quick jobs, but the battery heats up (and craps out) FAST during moderate use.

Ken

 

[BikeRider]

So it sounds like for my needs and budget it might be best to keep on doing it the way I have and deal with the modest inconvenience and short-term pain, than either waste money on a marginal tool or spend more than makes sense for me for a decent tool I'll rarely use after this work is done.

I mean, the methods I've used so far do work, and quite well. I got nearly everything down to bare metal and nearly so, and it was more than just a couple of parts. It's just slow and cumbersome, plus the hand issues (which have always gone away after a month or so). And most of the work is behind me now. So maybe it's better to save my money and not waste it on something either not that good or too good for my needs.

 

[Coach James]

I have the 421. I've used it several times including to cut apart a stuck deadbolt lock. It's worked fine, but not at the level of my corded Bosch and Makita units. I use mostly 1.5 amp-hour batteries. If I was going to be doing a lot of work every day, I would go with something else. For a few rusted bolts and similar things, I would be fine using the Ryobi.

Also, take a look at these folks. I have bought most of my Ryobi stuff through them.

https://www.directtoolsoutlet.com/

 

[Kaizen]

So it sounds like for my needs and budget it might be best to keep on doing it the way I have and deal with the modest inconvenience and short-term pain, than either waste money on a marginal tool or spend more than makes sense for me for a decent tool I'll rarely use after this work is done.

I mean, the methods I've used so far do work, and quite well. I got nearly everything down to bare metal and nearly so, and it was more than just a couple of parts. It's just slow and cumbersome, plus the hand issues (which have always gone away after a month or so). And most of the work is behind me now. So maybe it's better to save my money and not waste it on something either not that good or too good for my needs.

I have two corded ryobi ones from Hd. Think 30 bucks. Never get battery unless you absolutely need it away from power or you already have plenty of batteries. If gonna be sitting I’d get a corded. Grinder is a remarkable tool that you need in your arsenal


Sent from my iPhone using Garage Journal

 

[seber]

Some tools just don't work well with a battery. Tools that need to run a long time between charges should be corded. In most instances, angle grinders fall into that category. Also, table saws, miter saws, bench grinders, etc.

 

[anavrinIV]

I have a cordless Makita grinder that is a fantastic tool, but it will not match a corded one for big jobs. Biggest reason, as outlined above, is battery life. In heavy use a 5 ah battery will go from full to dead in 15 minutes. This is a powerful grinder (power matches the corded 4.5"s I've used) but it comes at the expense of battery life.

For your use corded is probably better. The good news here is a decent corded grinder can be had a good bit cheaper and will be more useful anywhere you can pull a cord.

 

[AGuinn]

I've had the P423 brushless for ~18mo. I usually keep it loaded with a flap wheel and for quick touch-ups and weld prep, it's awesome. It has quite a bit more torque than either of my corded grinders, but even with the higher capacity 4.0Ah batteries it ***** them dry in around 10-12 minutes. For large projects I'm reaching for one of my corded grinders.

 

[Kscardsfan]

Corded grinders are what you’re describing. Cordless grinders are for touch ups and cut offs etc in my experience.

 

[bargainhuntingking]

BikeRider,

You need some corded angle grinders for the work you describe. Wire wheels on drills are orders of magnitude less efficient than wire wheels on a 4.5” corded grinder. It’s like using a squirt gun compared to a pressure washer.

Get your first grinder and you will soon have 5, each with a different attachment: grinder, cut off wheel, knotted wire brush, knotted cup, wire cup, etc. so you don’t have to change accessories back and forth.

I’m just a DIY hack and have a half dozen from a $100 ~9amp German Metabo and a $5 ~4amp Harbor Freight, and variety of brands in between. Aside from the Metabo, these would not be considered good grinders by a pro but they all work well and perform the task at hand....

Take safety seriously. Those wire wheels will shed become little spears at 10k+RPM.

Once you get comfortable with them, you’d be amazed at how you got by without them.

Also, while you can start cheap to get a feel for the style you might prefer (shape [rat tail vs short and stubby, etc], weight, switch style [paddle, no lock, lock on, etc], your sensitivity to vibration means you might want a higher end model with demonstrated less vibration. I have tested my grinders back to back and find that for me vibration has more to do with the accessory attached than the grinder itself.

And no, don’t get a Ryobi.

 

[BlueWho]

My experience with angle grinders in general is that more power makes them amazingly more pleasant to use in a way that I didn't really appreciate from the numbers alone. Going from a cheap 6A grinder to a 12A grinder made regrinding lawnmower blades or heavy rust removal with a wire brush both faster and less aggravating. You're not going to regret more power even if you don't strictly need it.

The only recent cordless grinder that I've used much was a Bosch 18v 5" (GWX18V-50PCN). I really liked every aspect of it except for the lack of power. It had an excellent feel, was easy to hold and control, and I loved the quick and easy x-lock accessory mount and the fast electric brake. Even so it wasn't quite powerful enough for what I needed a cordless grinder for, so I had to return it. Still, I liked it enough that I'm going to give the new Bosch 18v spitfire x-lock 5-6" grinder a try. (I got it for $325 w/ a fast charger & 2 8AH batteries.)

A cheaper option might be the Kobalt 24v grinder. There's a promotion next month to get it free w/ the purchase of a 2 AH & 4 AH battery and charger starter kit for $129. I haven't used it but I've heard its pretty decent (for a cordless grinder) and I'm happy with my many other Kobalt 24v tools. Excellent value with usually enough power.

So it sounds like for my needs and budget it might be best to keep on doing it the way I have and deal with the modest inconvenience and short-term pain, than either waste money on a marginal tool or spend more than makes sense for me for a decent tool I'll rarely use after this work is done.

I mean, the methods I've used so far do work, and quite well. I got nearly everything down to bare metal and nearly so, and it was more than just a couple of parts. It's just slow and cumbersome, plus the hand issues (which have always gone away after a month or so). And most of the work is behind me now. So maybe it's better to save my money and not waste it on something either not that good or too good for my needs.

Please don't ignore the physical signs you get from your body. Injuries need to be taken seriously, especially if they last weeks to a month. It's not just a short term annoyance—there can be cumulative damage. Ignoring or toughing out something doesn't make it go away. Eventually there can be symptoms that don't go away so quickly, or even ever. At a lesser level, past injuries make future injuries more likely.

You may well have no long term issues from this project. But even if you'll never do something so harsh again, how much would you have to pay yourself to willingly endure all those nights of poor sleep?

I hate to spend more than I want to on equipment, but sometimes I have to remind myself that it's still cheaper than literally any amount of medical care.

 

[Ton ton]

My experience with angle grinders in general is that more power makes them amazingly more pleasant to use in a way that I didn't really appreciate from the numbers alone. Going from a cheap 6A grinder to a 12A grinder made regrinding lawnmower blades or heavy rust removal with a wire brush both faster and less aggravating. You're not going to regret more power even if you don't strictly need it.

The only recent cordless grinder that I've used much was a Bosch 18v 5" (GWX18V-50PCN). I really liked every aspect of it except for the lack of power. It had an excellent feel, was easy to hold and control, and I loved the quick and easy x-lock accessory mount and the fast electric brake. Even so it wasn't quite powerful enough for what I needed a cordless grinder for, so I had to return it. Still, I liked it enough that I'm going to give the new Bosch 18v spitfire x-lock 5-6" grinder a try. (I got it for $325 w/ a fast charger & 2 8AH batteries.)

A cheaper option might be the Kobalt 24v grinder. There's a promotion next month to get it free w/ the purchase of a 2 AH & 4 AH battery and charger starter kit for $129. I haven't used it but I've heard its pretty decent (for a cordless grinder) and I'm happy with my many other Kobalt 24v tools. Excellent value with usually enough power.



Please don't ignore the physical signs you get from your body. Injuries need to be taken seriously, especially if they last weeks to a month. It's not just a short term annoyance—there can be cumulative damage. Ignoring or toughing out something doesn't make it go away. Eventually there can be symptoms that don't go away so quickly, or even ever. At a lesser level, past injuries make future injuries more likely.

You may well have no long term issues from this project. But even if you'll never do something so harsh again, how much would you have to pay yourself to willingly endure all those nights of poor sleep?

I hate to spend more than I want to on equipment, but sometimes I have to remind myself that it's still cheaper than literally any amount of medical care.

I agree with the post above.

 

[56Mark]

Get a cheap corded one, even HF one, and you will see what you've been missing. One warning though, if you are using a wire brush on a grinder, get a full face shield. They throw a wire occasionally. I have pulled them out of me a few times. I had one sink in my leg about 1/2" once. Safety glasses at a minimum for other grinding/cutting.

 

[subroc]

I have little knowledge of the Ryobi tool you ask about.

Clearly, when getting involved with or undertaking any restoration of a rusted machine what mechanical clean or chemical clean or mix of the two we employ is dependent on how big the job, how rusty, flaked or surface rust, needed end result, expected finish, etc. I can say without question an offset grinder with a wire wheel is a "needed" tool for any metal prep especially rust removal.

I expect you will be well served with a tool like that for cleaning under car surfaces and parts. I have no opinion on brand or model.

An image of the tooling employed on Delta drill press base.

 

[joshmodelskidoo]

I had the craftsman c3 that was the same as that first ryobi grinder you showed. It worked good for small jobs. I got the dewalt one shown in another pic with the trigger and that’s way better but its brushed and eats the battery up. Go brushless and with a trigger or paddle switch is my recommendation. I don’t like the slide switch right next to the disk, scares me a bit

 

[paranoid56]

i have 3 of the 421s and they are ok. not amazing but work fine. if i know i am doing some long hard cuts i will get a corded one. but currently one has a cuttoff wheel, one has a flap disk, and one has a wire wheel. I might upgrade to the brushless one when one craps out.

 

[strutaeng]

I have a 421. It's marginal. For cutting off a bolt head on a roof -type of work is what I use mine. If you push it medium to hard, very easy to stall it.

My other grinders are a corded Metabo 4 1/2" and a corded Makita 7" beast grinder (nice for removing a LOT of material in a hurry, but really heavy,) then the Ryobi 421.

The one I bought the most recently is a corded 4 1/2", 5" and 6" grinder by Dewalt. Comes with those 3 guards. I'm really liking the 6" discs now. They cut much deeper than the 4 1/2". That's my go-to. It's got lots of power but still light enough. When I go back to the Ryobi, it looks like it's spinning in "slow motion" compared to the dewalt, LOL.

 

[BikeRider]

Thanks all for the very helpful responses. I'm now strongly leaning towards getting a corded one. Nothing fancy, in fact I might just pick up the basic HF one this weekend since it's on sale for $10.

I should mention, in case I didn't above, that whichever grinder I get, it will mainly be used to remove rust, using a combination of wire wheels and cups, abrasive wheels, and maybe a sanding wheel and even grinding wheel for really tough rust. I'll very, very rarely need to use a cutoff wheel, and even grinding will be very occasional. Would a low-end cordless grinder like the 421 be OK for just rust removal, and then for light to moderate rust?

Again, it's going to be hard to get the car close enough to where I can get a long extension cord to it, given the logistics of where I live and where the car is parked. I might be able to do it for a few hours, but anything involving getting the car on stands and keeping it that way till the job is done, which is likely to take a few days since I intend to remove parts and paint them, simply won't be possible with a corded grinder for me.

 

[strutaeng]

For light use like that, it will be okay. The problem is that running it for extended run times, the battery just doesn't last. You have to run those larger batteries, which only makes it a more fatiguing chore than it has to be. I run mine on 4Ah battery and I'd say it's probably the bare minimum.

You'll just have to be swapping batteries often if you are running it a lot.

I don't understand the whole push on those REALLY large battery pack manufacturers are pushing. Pretty soon, these battery packs are going to be the size of freaking car batteries. Consumers just keep drinking the Kool-Aid, LOL.

If you'd have a good supply of air (6 to 8 CFM), a needle scaler is a good tool for removal of heavy corrosion on things like frames and such in areas hard to get a grinder in.

 

[Rinspeed]

Thanks all for the very helpful responses. I'm now strongly leaning towards getting a corded one. Nothing fancy, in fact I might just pick up the basic HF one this weekend since it's on sale for $10.

Make sure you buy a face shield, abrasive cut off wheels can come apart and very possibly take a chunk out of your face.

 

[BikeRider]

Make sure you buy a face shield, abrasive cut off wheels can come apart and very possibly take a chunk out of your face.

Using a cutoff wheel will likely be by far the least common use of any angle grinder I buy, given the kinds of tasks I anticipate taking on. But I was going to get a face shield anyway, for use with a wire disc and cup. When I used drill versions of these last year, pieces of wire were constantly breaking off and some of them found their way into my skin.

None of it was really that painful. I'm not afraid of needles, shots, blood drawing, etc. But obviously one's face and especially eyes make for poor pincushions. I wore goggles, but I should really protect my whole face, especially when using a much higher RPM grinder compared to a drill or driver. I imagine that can actually be painful and go deeper.

 

[BikeRider]

For light use like that, it will be okay. The problem is that running it for extended run times, the battery just doesn't last. You have to run those larger batteries, which only makes it a more fatiguing chore than it has to be. I run mine on 4Ah battery and I'd say it's probably the bare minimum.

You'll just have to be swapping batteries often if you are running it a lot.

I don't understand the whole push on those REALLY large battery pack manufacturers are pushing. Pretty soon, these battery packs are going to be the size of freaking car batteries. Consumers just keep drinking the Kool-Aid, LOL.

If you'd have a good supply of air (6 to 8 CFM), a needle scaler is a good tool for removal of heavy corrosion on things like frames and such in areas hard to get a grinder in.

Still on the fence. I might get both a cordless and corded, especially with the latter just $10 this weekend at HF. I wonder if it's possible and advisable to run a corded grinder off a car battery, using an inverter, especially with the car running, or maybe not, for short stretches, and whether this would damage the tool and/or battery.

I also wonder why, with some of these high power cordless tools running batteries down fast, someone doesn't come out with a line of tools that are technically cordless, running off batteries, but with the battery not directly attached to the tool, rather a standalone battery around the size of a motorcycle battery, connected to the tool with a cord. This would allow you to run a cordless tool for longer stretches than with an attached battery, and make the tool lighter.

In any case, the worst of the rust has already been removed, with the remaining rust being mostly on rear subframe components, like the actual subframe, the differential carrier and differential itself, and some other smallish pieces like mounting brackets, most of which can be removed. I've already derusted and painted or replaced most of the the suspension components. So I can remove these parts and derust them near where I can bring out an extension cord, and the relatively few parts that have to stay on the car I can used a cordless grinder on. Perhaps that's the best approach.

 

[Mallen]

I've never owned or used an angle grinder and have put off buying one till now. The main use I'd have for one is removing tough rust from complexly-shaped structural auto parts, e.g. control arms, brake calipers, suspension springs, manifolds, etc. I've been restoring a 29 year old car and working on some other older cars, each with plenty of rust, and so far I've been using a combination of power drills and an impact driver with wire brush, abrasive and grinder wheels, a rotary tool for hard to reach spots, and a scraper and set of picks.

It's worked pretty well but it's a really slow and laborious process, and the vibrations really mess up my hands for weeks afterwards, with a kind of peripheral neuropathy setting in that makes it hard to fall and stay asleep. It's probably not that great for these tools either, as they're not really meant to do this sort of thing on an extended basis. There's still a fair amount of rust removal work to be done, so I'm thinking of getting a cordless angle grinder to make it easier and safer this time. It has to be cordless as I work on my car on the street and there's no easy way to get an extension cord there.

Since my needs aren't too advanced, I don't anticipate doing much grinding or cutting beyond the occasional stuck bolt or stud, and once I'm done restoring and fixing these cars the grinder will probably stay in its bag most of the time, I thought I'd go with a decent lower-end model, and the one that caught my eye was the Ryobi P421, which is on sale right now at Home Depot as part of a promo deal where I can get the tool, 2 4Ah LiOn batteries, and a charger, for $100. Seems like a decent deal. But it's their most basic cordless grinder that normally sells for around $45 and is not brushless. They have 2 more expensive models that are both brushless, smaller, lighter, and run much faster, like nearly twice as fast (~10,000rpm vs. ~6000rpm).

RYOBI ONE+ 18V Cordless 4-1/2 in. Angle Grinder (Tool-Only) P421 - The Home Depot

RYOBI introduces the 18V ONE+ Cordless 4-1/2 in. Angle Grinder (Tool-Only). The ONE+ 4-1/2 in. Angle Grinder offers cordless convenience and the power of 6500 RPM for fast and precise work. This tool offers a host of user-friendly features, such as onboard wrench storage, the comfortable...

www.homedepot.com

RYOBI ONE+ 18V Brushless Cordless 4-1/2 in. Angle Grinder Kit with (1) 1.5 Ah Battery and Charger P423KN

RYOBI introduces the 18V ONE+ Cordless Brushless 4-1/2 in. Cut-Off Tool/Angle Grinder Kit with 1.5 Ah Battery and Charger. The brushless motor in the 4-1/2 in. Angle Grinder provides longer runtime, more

www.homedepot.com

RYOBI ONE+ HP 18V Brushless Cordless 4-1/ 2 in. Angle Grinder Kit with (1) 4.0 Ah Battery and Charger-PBLAG01K - The Home Depot

The RYOBI 18V ONE+ HP Brushless line of products is redefining power and performance. The RYOBI 18V ONE+ HP Brushless 4-1/2 in. Angle Grinder/Cut-Off Tool (PBLAG01B) provides up to 30% faster cutting and also provides up to 9,200 RPM to help complete your next project more efficiently and...

www.homedepot.com

So I'm wondering, for my needs, is the P421 ok, or would I be best served going with one of the brushless models, or perhaps going with a different brand entirely? I can afford a somewhat nicer grinder, it's just that I don't know that I can justify it for my needs. So I guess I'm asking if for all its limitations the P421 is still a decent grinder, and perfectly fine for the occasional weekend mechanic like me?

I'd get a Metabo hpt grinder. I have one that's 15 years old. I've beat on it and beat on it and it still works great. And they are very reasonable priced. https://www.lowes.com/pd/Metabo-HPT...liding-Switch-Corded-Angle-Grinder/1001107544

 

[tyyost]

I also wonder why, with some of these high power cordless tools running batteries down fast, someone doesn't come out with a line of tools that are technically cordless, running off batteries, but with the battery not directly attached to the tool, rather a standalone battery around the size of a motorcycle battery, connected to the tool with a cord. This would allow you to run a cordless tool for longer stretches than with an attached battery, and make the tool lighter.

I’d put my Milwaukee fuel cordless grinder with a 6.0 battery up any day against corded for jobs you describe. That said, cost is 10x what you were looking to spend. I’ve been using angle grinders for car and truck resto work for over 30 years. We have done several frame off jobs where sandblasting wasn’t an option, with tons of consumables. They are incredibly versatile tools, and every one should have one in their box.

My first cordless grinder was a Milwaukee 1st gen non-fuel. It was a dog. I wouldn’t wish it on my enemy it was so slow and burned through charged batteries like it was OPE. The fuel is much more capable, but corded grinders are still lighter, more maneuverable, and often cheaper.

I love a good “Help me spend my $$$ thread“ as much as the next guy, but buy the $50 or so DeWalt Grinder and some HF consumables and give it a whirl. You are missing out.

 

[Mallen]

Still on the fence. I might get both a cordless and corded, especially with the latter just $10 this weekend at HF. I wonder if it's possible and advisable to run a corded grinder off a car battery, using an inverter, especially with the car running, or maybe not, for short stretches, and whether this would damage the tool and/or battery.

I also wonder why, with some of these high power cordless tools running batteries down fast, someone doesn't come out with a line of tools that are technically cordless, running off batteries, but with the battery not directly attached to the tool, rather a standalone battery around the size of a motorcycle battery, connected to the tool with a cord. This would allow you to run a cordless tool for longer stretches than with an attached battery, and make the tool lighter.

In any case, the worst of the rust has already been removed, with the remaining rust being mostly on rear subframe components, like the actual subframe, the differential carrier and differential itself, and some other smallish pieces like mounting brackets, most of which can be removed. I've already derusted and painted or replaced most of the the suspension components. So I can remove these parts and derust them near where I can bring out an extension cord, and the relatively few parts that have to stay on the car I can used a cordless grinder on. Perhaps that's the best approach.

Don't even bother with the harbor freight unit. Its a waste if money. The cheap hf angle grinders are said not to last past a single use. 40 bucks will buy you a Metabo HPT grinder from Lowes. I like mine (it's actually a Hitachi from before they changed the name). I'd recommend it. But , there are plenty of decent ones for a little more or less. Angle grinders get used hard. A cheap hf one just isn't going to hack it.

Now that I've said do t get the hf one, I'm going to tell you the opposite. If you actually do t know what features you want or need, go get the hf one. Use it hard until it breaks and keep your receipt. When it breaks, return it. Then go buy a good one now that you know what you need.

But if still recommend just getting the Metabo hpt. Its cheap. It does the job well. And it had a good warranty.

In a similar thing to what you suggest, I have a Metabo hpt multicolor grinder as well. It uses a 36v battery back, has variable speed and has a ac adapter so you can run it as a corded tool, although it has slightly reduced power on ac. I do t see the point of a large external battery myself. The big lithium ion packs these days have huge amounts of power. An external pack is just "the worst of both worlds". Not only do you need to recharge it, but your still tethered to a cord and it's going to be very expensive.

If you want to run it off an inverter you going to need a robust one. I've ran a drill off an inverter. It worked of but sometimes tripped the breaker. My suggestion would be to get a small portable generator if you want portability from cordless tools. That's works really well. Back in the day when cordless tools just weren't up to their corded counterparts that was the only option. These days though, high end cordless tools are competative. In fact, cordless impact wrenches are now able to exceed the capabilities of typical pneumatic ones.

One place you MUST have a cordless tool is when working with water like wet grinding a concrete counter top. Or my favorite, putting a brush on my drill and scrubbing the bathtub. You will find you use your angle grinder far more than you think. You will find interesting jobs for it. Its versatile and takes many kinds of blades.

I suggest you think about the battery system your getting into. You will want to get a brand that offers all the tools you will want in the future. Probably a good drill. Maybe saws of various kinds. A big impact wrench. Honestly, if I were just going to go out and buy something, I'd have to say Milwaukee , followed by Makita. Much as I like my Metabo hpt stuff, there are tools I want they just do t make.

 

[tarbellb]

Don't even bother with the harbor freight unit. Its a waste if money. The cheap hf angle grinders are said not to last past a single use. 40 bucks ......

Simply not true

You will find 100s of replies on here about users beating the snot out of HF $10 grinders and they just keep going.


I agree there are other better cheap grinders, Hitachi is what I recommend as well. I have 8+ grinders, Fein, Metabo, the brushless corded Hitachi, M18 Fuel, etc.... all very nice. But a grinder is a very basic tool that you can go cheap on not regret to much.


Now battery operated grinders are a different story, its a HIGH demand tool and you really want the best performance you can achieve from that battery+motor.

I consider the M18 Fuel the minimum acceptable performance for a grinder.
In other words- go big$ or go corded

 

[Mallen]

Weight is another issue on cordless. This batteries can be heavy.

 

[Badgerstate]

I've never owned or used an angle grinder and have put off buying one till now. The main use I'd have for one is removing tough rust from complexly-shaped structural auto parts, e.g. control arms, brake calipers, suspension springs, manifolds, etc. I've been restoring a 29 year old car and working on some other older cars, each with plenty of rust, and so far I've been using a combination of power drills and an impact driver with wire brush, abrasive and grinder wheels, a rotary tool for hard to reach spots, and a scraper and set of picks.

It's worked pretty well but it's a really slow and laborious process, and the vibrations really mess up my hands for weeks afterwards, with a kind of peripheral neuropathy setting in that makes it hard to fall and stay asleep. It's probably not that great for these tools either, as they're not really meant to do this sort of thing on an extended basis. There's still a fair amount of rust removal work to be done, so I'm thinking of getting a cordless angle grinder to make it easier and safer this time. It has to be cordless as I work on my car on the street and there's no easy way to get an extension cord there.

Since my needs aren't too advanced, I don't anticipate doing much grinding or cutting beyond the occasional stuck bolt or stud, and once I'm done restoring and fixing these cars the grinder will probably stay in its bag most of the time, I thought I'd go with a decent lower-end model, and the one that caught my eye was the Ryobi P421, which is on sale right now at Home Depot as part of a promo deal where I can get the tool, 2 4Ah LiOn batteries, and a charger, for $100. Seems like a decent deal. But it's their most basic cordless grinder that normally sells for around $45 and is not brushless. They have 2 more expensive models that are both brushless, smaller, lighter, and run much faster, like nearly twice as fast (~10,000rpm vs. ~6000rpm).

RYOBI ONE+ 18V Cordless 4-1/2 in. Angle Grinder (Tool-Only) P421 - The Home Depot

RYOBI introduces the 18V ONE+ Cordless 4-1/2 in. Angle Grinder (Tool-Only). The ONE+ 4-1/2 in. Angle Grinder offers cordless convenience and the power of 6500 RPM for fast and precise work. This tool offers a host of user-friendly features, such as onboard wrench storage, the comfortable...

www.homedepot.com

RYOBI ONE+ 18V Brushless Cordless 4-1/2 in. Angle Grinder Kit with (1) 1.5 Ah Battery and Charger P423KN

RYOBI introduces the 18V ONE+ Cordless Brushless 4-1/2 in. Cut-Off Tool/Angle Grinder Kit with 1.5 Ah Battery and Charger. The brushless motor in the 4-1/2 in. Angle Grinder provides longer runtime, more

www.homedepot.com

RYOBI ONE+ HP 18V Brushless Cordless 4-1/ 2 in. Angle Grinder Kit with (1) 4.0 Ah Battery and Charger-PBLAG01K - The Home Depot

The RYOBI 18V ONE+ HP Brushless line of products is redefining power and performance. The RYOBI 18V ONE+ HP Brushless 4-1/2 in. Angle Grinder/Cut-Off Tool (PBLAG01B) provides up to 30% faster cutting and also provides up to 9,200 RPM to help complete your next project more efficiently and...

www.homedepot.com

So I'm wondering, for my needs, is the P421 ok, or would I be best served going with one of the brushless models, or perhaps going with a different brand entirely? I can afford a somewhat nicer grinder, it's just that I don't know that I can justify it for my needs. So I guess I'm asking if for all its limitations the P421 is still a decent grinder, and perfectly fine for the occasional weekend mechanic like me?

Id personally go corded instead. Cordless is fine for smaller jobs but to do bigger jobs youre going to either need to use a big battery, which will make the tool heavier and more cumbersome or you will need to have several batteries.
If it were me, Id pick up a 4.5" corded grinder. Id go Milwaukee and even going Milwaukee its only going to cost you about $65 for a 7 amp model, which is pretty powerful for an angle grinder. They make an 11 amp one too if you need to step up to it.

 

[seber]

For the money, it's hard to beat the Hitachi 4 1/2". They are now labeled Metabo but in Hitachi green. As much as I love my Milwaukee tools, I would not buy a Milwaukee angle grinder. I've thrown several away over the years. Weak switches.

 

[Syberia]

Simply not true

You will find 100s of replies on here about users beating the snot out of HF $10 grinders and they just keep going.

All I know is from my experience I stripped the gears in two of them in short order grinding and wire-wheeling welds. Replaced with a $30 corded Ryobi that's lasted years, although I plan on getting the 24v cordless Kobalt soon for light-duty work (mostly using cutoff wheels) when I'm not near an outlet. I already have plenty of the batteries.

 

[tarbellb]

All I know is from my experience I stripped the gears in two of them in short order grinding and wire-wheeling welds. Replaced with a $30 corded Ryobi that's lasted years, although I plan on getting the 24v cordless Kobalt soon for light-duty work (mostly using cutoff wheels) when I'm not near an outlet. I already have plenty of the batteries.

Now a HF tool shitting the bed out the box is not that uncommon, I see why you have your opinion.