wire wheel brush angle grinder speed rating?

[CopperCone]

Are wire wheel brushes designed to be crap, or do I need to get an angle grinder with speed control? I have a m18 fuel angle grinder and a brushless dewalt angle grinder (this thing is a beast). They seem to get used up really fast.

I found that the regular types of wire wheels, like this one from milwakee (i don't buy harbor freight shit)
https://www.homedepot.com/p/Milwaukee-4-in-Crimped-Wire-Wheel-Brush-48-52-5070/100015130

Are a complete pain in the ass. They shoot out the back of the grinder like fletchets and impale my shirt very frequently, and their life time is very short.

The knotted ones seem to last alot longer, but you can't really jam them into crevices and stuff. I seem to get longer life out of quality flap disks then wire wheels that are unknotted!

The rating says 12000 RPM, but is this a lie?

by knotted I mean like this:
https://www.homedepot.com/p/Milwaukee-3-in-Brush-Knot-Cup-48-52-5050/100020099

Does milwakee just suck?

[Gregg]

A variable speed angle grinder is a great investment to make wire brushes last longer and to keep things like paint from loading sandpaper as quickly.  Get a good one with feedback speed control, Milwaukee has one of the most stable speed controls, Metabo, Bosch and Makita are very good, Dewalt's newer models seem very good but Hitachi  speed control wants to hunt and sag a lot.  A consideration for many is the type of switch, paddle or slide and with paddle switches most have safety toggles that can be a royal pain to use. 
With wire wheels the twisted or knotted type are the way to go unless you specifically need some obscure feature of the crimped type.  Lehigh Valley Abrasives is a good source and KBC tools sometimes has unbeatable prices with their monthly sales. 
Flap wheels usually last longer at lower RPM and so do the Scotchbrite type of woven abrasives. 

[CopperCone]

is there one thats battery powered and decent?

I am extremely impressed by the power of the 60V dewalt grinder, and the milwakee fuel one is decent

The only variable speed angle grinder like thing I could find is this:
https://www.homedepot.com/p/Milwaukee-M18-FUEL-18-Volt-Lithium-Ion-Brushless-Cordless-7-in-Variable-Speed-Polisher-Tool-Only-2738-20/207163625

But its a polisher, and its max is only 2200RPM. That might be too low, and I don't know if the gearing and shit inside of it can tollerate the stresses of metal brushing and it has no guard etc.

I don't really like corded hand tools very much.. but with how crimped brushes are eaten by full speed grinders, I may not have a choice.

[CopperCone]

actually it seems the makita has a adjustment

https://www.homedepot.com/p/Makita-18-Volt-Brushless-4-1-2-in-5-in-Cordless-Paddle-Switch-Cut-Off-Angle-Grinder-with-Electric-Brake-and-AWS-Tool-Only-XAG21ZU/304303559

Well, its on my wish list... so long 2000RPM minimum is alright? I assume it will be alot better then 8000 or whatever the current ones I own are.

Not that having a bunch of different angle grinders is bad anyway, I hate doing blade changes all the time during a job.

[tautech]

The only ones that really last are twist knot cup brushes as they have thick bristles. Ordinary cup brushes usually have finer bristles and they shed them all the time.
RPM rating is the key here and if you put a 3" brush on a 12k rpm tool it's gunna fly to bits.
Careful matching of the brush to the tool will give the best life.

[Electro Detective]

I use variable speed corded 115mm or 125mm grinders (hard pressed to find them now) with various wire wheels and play with the speed control to get the correct 'crap removal' speed
that doesn't impact on the health of the wire wheels, and keep the 'spinning heat n friction' down a tad,
and of course the technique of 'let the tool do the work' and go easy on the force.
So far there's been no unexpected wear and tear, they last ages 

Same deal with the flap discs and abrasive cut/grind discs

The speed rating on these consumables is partly so people don't put lower speed discs better suited for drills on high speed grinders, saws etc  and wack themselves out   

i.e. even though they will persevere, you don't have to use them at full stick.
 

It's too bad 100mm grinders don't come with speed controls, they are less of a handful to use and the discs cheaper

Not sure if a variac or chopped voltage thingie would fit the bill here, even though they are brushed/universal motors   

Hmmm, might see what the local tool repair shop guru can offer as a mod... 
 

[Gregg]

Coppercone:
I would think 2000 RPM or even 3000 RPM minimum would be quite nice for your purposes.  There are many other sources for them other than Home Depot that may be cheaper, but at least you can go and handle one at a local store to see if you like the feel.  I often find that HD has very competitive pricing and they give me a veteran’s discount of 10%.
The surface speed of the wire tips is the main consideration.  Normal bench grinders in the US turn 3600 RPM and work quite well with a 6 inch wire wheel.  I have a 10 inch wire wheel on a 1800 RPM pedestal grinder and it goes like crazy; I wouldn’t want it any faster.
All of my angle grinders are corded or pneumatic, so I can’t vouch for any of the battery ones.  I do have Milwaukee M18 Fuel drills and impacts that I have no complaints about. 
You will get better life and productivity out of wire wheels if you get ones that allow you to change the direction often.  It will keep the ends sharper and not allow the individual wires to take a directional set.

[Dubbie]

I use a small twisted wire cup on a 4 1/2" grinder at full speed and found that it has lasted absolutely ages. Was just marvelling at that the other day.

http://tgaabrasives.co.nz/product/bordo-twist-knot-cup-brushes/

I've used the straight/crimped wire ones before and spend ages picking the needles out of myself afterwards.

I can't recall ever finding a single needle where it shouldn't be with these guys.

[CopperCone]

yea I was brushing away with my dewalt 60v brush less angle grinder for like an hour (some battery changes) last night restoring this rusted over piece of shit using a knotted cup brush (the non stainless type from milwakee) and it hardly wore. They say it has the power of the 10A corded grinder, so it shows the durability of those cup brushes.

I am not buying any more crimped wire wheels until I get a variable speed grinder though.

[Rabid Badger]

That Makita is a quality tool. 

If you decide you don't want to have another set of batteries to deal with, this Fein is an excellent option with TONS of power and very low vibration (for an angle grinder).

https://www.amazon.com/Fein-Variable-Speed-Angle-Grinder/dp/B00PX0VXZI

[CopperCone]

unfortunately I have dremel, Makita, Milwakee, ryobi, skill, dewalt and rigid battery packs 

thankfully the automatic screwdriver black and decker has a integrated battery and USB.....

I was thinking that I should get rid of the rigid, since milwakee came out with a nice orbital sander now, but I like their pulse driver quite a bit. I don't think i can part with it. I don't know if I like the milwakee pulse driver so much, the rigid is nice and beefy, and the noise is more pleasant (main idea why I like it) vs the milwakee that still sounds like a god damn woodpecker.

tho with the rigid it seems like you can defiantly feel the entire tool kinda convulse in your hands, I read maybe the hydraulic fluid path is bigger, but on the low speeds you can basically break into a house and build them a patio and the home owner might not notice LOL