Correct size wire cup brush for small angle grinder?

[stickshift]

I have a 4-1/2" small angle grinder and need to get a crimped wire cup brush.

I see 3" and 4" versions. For example, 3": https://www.harborfreight.com/3-inch-crimped-wire-cup-brush-65009.html

And 4": https://www.harborfreight.com/4-in-crimped-wire-cup-brush-60321.html

Which is the correct size to use with this grinder and guard (guard is 1" deep)?

 

[Wamsutta]

The max RPM will be written right on the top of the wire brush. For 11,000 RPM, usually a 2-3/4 inch brush is the largest you can go. Going with an oversize brush will fry your grinder fairly quick. You don't need the guard on for wire brushes.

 

[stickshift]

The max RPM will be written right on the top of the wire brush. For 11,000 RPM, usually a 2-3/4 inch brush is the largest you can go. Going with an oversize brush will fry your grinder fairly quick.

Yeah my grinder is 10A 11k RPM. The HF 4" brush is 8k RPM, the 3" brush is 8.5k RPM, and another 3" brush is 10k RPM.

So I guess all of these overwork the grinder. Surprised HF doesn't have a 2-3/4" option.

My grinder thanks you for saving its life.

You don't need the guard on for wire brushes.

I was thinking the guard would help shield me from the tiny steel darts that I'm sure will be flung in my general direction.

Speaking of, without a guard, is one layer pants and long sleeve shirt sufficient (in addition to face shield), or is more protection necessary to avoid looking like Pinhead from Hellraiser?

 

[driz]

I use the biggest I can get on. Then again I never use a shield on one anyways, no way too useless for me anyways. I just use a shield and do my thing.
I use whatever brand that’s cheap and am happy but for ONE ,HF[emoji2961]. Of em all. They are the ONLY ones I’ve ever seen to spit wires REGULARLY. Many have severe imbalance issues at speed too. HF also have the nasty habit of such a thin backer that it collapses downwards enough that you can’t get at them with a wrench[emoji82]. Thanks to HF I taught myself to just go wrenchless and only use a gloved hand. I try to grab Forney if I can for price . No other brand ever routinely tossed needles at least till it was worn yo near death.
Don’t get me wrong I use a lot of HF tools and they’re fine. Just not any of their hi speed wire wheels. Bench grinder wheels work fine! I know you’re asking about size not brand but digging needles out of your arm hurts so I thought I’d warn you.


Sent from my iPad using Tapatalk

 

[rlitman]

...My grinder thanks you for saving its life.
I was thinking the guard would help shield me from the tiny steel darts that I'm sure will be flung in my general direction.

Speaking of, without a guard, is one layer pants and long sleeve shirt sufficient (in addition to face shield), or is more protection necessary to avoid looking like Pinhead from Hellraiser?

Ha, no.

First off, the max rpm of the attachment is to save you, not the tool. Spinning the wire brush too fast will cause it to fall apart, potentially dangerously.

Second, I usually wear one layer of denim pants when power brushing. The wires shoot out SO fast that they will generally poke you to the point of bleeding, even through denim. A leather apron works wonders here.

 

[cherrybomb]

I'm not sure how to answer the question but food for thought,for safety I just wanted a variable speed grinder for that situation. I take blood thinners,so thats just me,thinking about picking out wire.

 

[driz]

I'm not sure how to answer the question but food for thought,for safety I just wanted a variable speed grinder for that situation. I take blood thinners,so thats just me,thinking about picking out wire.

It gets annoying pulling those things. Ya don’t wanna go bleeding all over, leaves a sticky mess[emoji847]. They get you another way too. The majority are flung everywhere. They come back to haunt you later when you feel something poking your foot and find one. Those don’t come out without pliers usually either.
Honestly I’ve always liked Forney as a middle ground. Half the price of Makita ect and last oh say 3/4 as long. Another thing I use amazingly often is a dremel brush. Wimpy yea but that tiny stainless brush gets in where others won’t . Fantastic for cleaning cruddy electrical terminals. Don’t get the name brand either[emoji389][emoji389]. Online jewelry supplies on eBay sell them by the bag of 20 for about $22 vs. $4-5 each. Very fragile all of them but last ok if you’re not gorilla fisted.


Sent from my iPad using Tapatalk

 

[3jakes]

Just want to pile on the "safety issue"
I will regularly hit the bench grinder wire wheel, take a little rust off without glasses by "standing off to the side & get away with it"
But on these wire wheels, face mask & gloves.
The first time I used one, I was turning into a porcupine before I knew what hit me...

 

[bwringer]

I'll agree with "anything but Harbor Freight".

I mean, sure, grab several of the HF $10 angle grinders and put a different implement on each. They're fantastic for the money, and astonishingly hard to kill.

But get the brushes somewhere else. Anywhere else.

 

[stickshift]

The warnings about the HF brushes will be heeded, and I'll go with Dewalt.

How far do the wires get flung? I'm planning on using this in my driveway. How far away do I need to be from the garage so that the garage door doesn't end up looking like a dartboard? Also need to keep my car at a safe distance.

These wires are so small, they must lose speed quickly, but never having used a crimped wire cup brush, I'm not sure if it's a couple of feet or a dozen feet.

 

[rlitman]

I can't say I've seen them stuck into anything other than myself and my clothing, so I'm guessing not too far.

 

[Wamsutta]

A good quality brush won't shed wire bristles as long as you're using it at the correct RPM. HF wouldn't be my choice for that very reason.

I would go with Osborn or Weiler.

 

[rlitman]

A good quality brush won't shed wire bristles as long as you're using it at the correct RPM. HF wouldn't be my choice for that very reason.

I would go with Osborn or Weiler.

Have you ever used one of these? I've used them all; good, bad, expensive, cheap. Rotary wire brushes shed, unless you're talking about an encapsulated brush. Good brushes shed more slowly, but they will all shed eventually.

 

[MoonRise]

Use a wire brush, and it WILL shed the wires.

Use a wire brush at an rpm higher than it is 'rated' for and it WILL shed the wires even faster and MAY spin apart (destructively).

The wires WILL stick into your skin, sometimes right through your pants. Ouch. BTDT, through work pants and denim jeans. Including some that hit me in 'sensitive' areas. #%$$@@@. And also plucking the wires out of yourself and the pants is a pain (literally from your self and figuratively from the pants).

Don't even THINK about using wire brushes on an angle grinder without PPE. Full face shield with safety glasses underneath is essential, leather shop apron and/or welding jacket to protect the torso/arms/legs.

Work gloves CAREFULLY, sleeves CAREFULLY .

Definitely do NOT want to get clothing tangled into an angle grinder. Especially if the grinder does NOT have a paddle power switch which will not lock/stay on once you let go (or the grinder is ripped out of your hands at 11k rpm with 1+ hp of motor spinning it when it gets jammed/tangled in something).

The shed wires will easily fly ~10 feet. They won't stick into you at that distance, but eyes still need to be protected and you will be finding wires that far away. A shop magnetic-bar-pick-up-tool works wonders (wrap it with a thin paper/plastic layer first to make removing the wires and metal dust easier and not just end up with a metal dust and wire coated magnet).

I don't even bother with a crimped wire cup brush on an angle grinder. If I'm pulling out an angle grinder with a wire brush on it, I'm using a knotted wire one. YMMV and all that.

Crimped example:

https://www.weilercorp.com/crimped-wire-cup-brushes

Knotted example:

https://www.weilercorp.com/knot-wire-cup-brushes

Grinder rated at 11k rpm? You NEED a brush (or other implement) rated at LEAST to that rpm.

These cup knotted wire brushes are rate for 12k rpm max, the Weilers seem to be 10 k rpm rated (no good on an 11k rpm grinder).

https://www.walter.com/products/power-brushes/wire-cup-brushes/cup-brush-knot-twisted-wires

 

[driz]

The warnings about the HF brushes will be heeded, and I'll go with Dewalt.

How far do the wires get flung? I'm planning on using this in my driveway. How far away do I need to be from the garage so that the garage door doesn't end up looking like a dartboard? Also need to keep my car at a safe distance.

These wires are so small, they must lose speed quickly, but never having used a crimped wire cup brush, I'm not sure if it's a couple of feet or a dozen feet.

I wouldn’t worry much about hurting anything 20’ away . The one you really want to watch Is GRINDING near your cars. Those hot specs will unnoticed dig into the clear and even the glass leaving tiny craters.
I wouldn’t sweat the wire wheels nearly as much but it’s still a good idea to keep vehicles at a safe distance or toss an old sheet or rug over if the cars immobile.
Don’t let that wire wheel eat your loose hanging T Shirt. It’ll grab on try to run up till it sticks Then you get to pry it off. Wrecks a good shirt and leaves you looking like a pissed off wolverine got stuck in your shirt. Kinda hurts[emoji6]


Sent from my iPad using Tapatalk

 

[sberry]

I have a cup or 2, never use them. I like right angle with a guard if possible.

 

[Wamsutta]

Have you ever used one of these? I've used them all; good, bad, expensive, cheap. Rotary wire brushes shed, unless you're talking about an encapsulated brush. Good brushes shed more slowly, but they will all shed eventually.

Yes I've used them at their rated RPM. They don't shed wires, but the wires wear down eventually over a long period of time. Using the right RPM is key. Centrifugal force can be brutal.

 

[tarbellb]

Lots of good advice already on here, but to recap from a job where I wore out literally dozens of wire cups on a 4.5" grinder(s).

_ dont go bigger then 3"

_ dont buy HF, they wear much faster

_ do buy Weiler, Pferd, Norton? ie USA or Euro

_ they all shoot wires, but quality much less so.

_ wear is exponential

_ 1 layer of clothing is totally fine, but leather is best

_ goggles recommended

_ again, DONT BUY HF- heres a Weiler for $9, will last 4x longer
https://www.amazon.com/dp/B004HMOGXO/?tag=atomicindus08-20

 

[driftpin]

Weiler is much-better than most-others. Norton is good too. I've used HFT and have multiple grinders, w/multiple attachments, so I don't need to stop and switch-out an attachment, because I want to use a flapper wheel, a grinding wheel, a cut-off disc, a wire wheel, or a sanding disc. Yes to eye protection, always. If I was going to be doing extensive work, I'd use additional protection. I don't have an apron, but I've been thinking about getting one. I have used a denim jean jacket, which seems to work pretty-well for protecting me from the work I do. If I was in a shipyard or an industrial setting where the tool was being used for hours, then the PPE in a heavy-duty format would be what I'd want.

More-than once on fire-rescue I had to remind a co-worker to use his visor, you'd think it was second nature, but sometimes people forget, or are careless. If you're 'on-air,' (SCBA-self-contained breathing apparatus) you have a mask-on, so you're protected.