Never owned one before and picked one up to sharpen my flail mower blades.

The grinding wheel I picked up is threaded (Milwaukee guy at the big box store recommended it)



Far as I can tell I shouldn't be using the flange or flange nut with this wheel. Arbor isn't long enough even it I wanted too. In RTFM all it says about threaded hub wheels is that I might need a deeper guard. Nothing about particulars on them.

Problem is that the wheel will spin off, which is fun. Am I just not getting the wheel on there tight enough or is there a trick?

Proper threads?

I have several grinders, and every blankety blanking
one of them is a different metric thread and pitch

Every angle grinder I ever used, the wheel spun on opposite to direction of rotation. So in operation, the wheel just wants to get tighter and tighter.

I lock the shaft, and tighten the wheel firmly by hand. Then I usually have to find a wrench to remove it.

If my mower blade is not too screwed up, I like to use a sanding disc to sharpen it. It cuts a lot slower, does not nick the blade, and is less likely to burn the temper out in places.

My mind saw “Angie Grinder” and I got excited.

bingo

Good choice of wheel. One of the best. As stated this wheel only has to be screwed on to the arbor. If it's flying off. you're not getting it tight enough. The flange nut is only used if the wheel doesn't have threads. Like on the skinny wheels used for cutting.

And I hope you got a grinder with a paddle switch.

Interesting, first I have seen with an included thread.

Type 27.

There’s several different styles.

Unless blades had some rock damage, I’d use a flapper wheel.

I've never seen a mower blade without rock nicks.

It says it's a 5/8-11 thread and it'll be right handed. That's standard as far as I know. As said before, hand tighten it and the rotation will snug it up.
When sharpening any blade, GO SLOW. Don't get it hot enough to turn black. That will ruin the temper and it won't hold an edge after that. I'm no expert on steel. Maybe someone who is will tell us the best way to do it.

Wear safety gear.

I use a flapper wheel - 40 grit. Does a great job on bush hog blades.

The sanding disc will move metal as fast or faster than a solid rock disc, and produce as much heat. Guys in the metal trades call them a "Tiger Paw"

It does produce a smoother finish.

I wanna guess that 99.9 percent of the electric grinders I've used were made by Metabo, Dewalt, or Milwaukee. 4 1/2", 6", 7" and 9" all have the same arbor, and will all take the same threaded center disc

There will be a shaft/wheel lock on your grinder. depress it and spin your disc on snugly. If the disc comes off your motor is turning backwards. From the top. looking down it should turn to the right, or clockwise.

Locking switches on a grinder are just maybe the most wrongly maligned item in the construction world. Give an idiot a grinder and he will hurt himself sooner or later, regardless of switch style.

It is easy to demonstrate that the paddle switch is more dangerous in some positions used in normal grinding operations

My grinder is an old Craftsman, labeled 'MADE IN USA'. That's before they labeled them Mattel. I've probably had it 40 years or more and it's still working great. It has a switch.

As stated above use safety gear a specially eye protection.
I have been using grinders for over 45 years.
They are more dangerous than a lot of other power tools
Eye protection is the most important of all
It is very unnerving watching a doctor with a hand held dremal coming towards your eye while you watch.
I personally know how that is.
I got a sliver in the center of my pupil from a grinder.
I was wearing my eye glasses to see with and a welders hood for eye protection and still got a dart in the eye.
Long sleeve cotton shirt and gloves. No nylon

If it was my project. I would start with the hard wheel and finish the job up with a flapper disc
Flappers are expensive compared to the hard discs.
Once you use a grinder you will be looking for more things to grind up and destroy they can be fun to use at times.

It looks like the salesman led you right
Good luck with your project

This 👆🏻

Take it back and exchange it for a non-threaded 4.5" wheel, 1/4" thick, with a 7/8" arbor hole. That way you can use the spacer flange and nut that come with the grinder and save your self a $1 or $2. The threaded type, like you have pictured, cost more. Get a 4.5" 60 grit flap wheel, with 7/8" arbor hole (non-threaded) also.

Is it unthreading while under power? Or when power is removed?

As said above, Under power should be self tightening.

I’ve seen them when not snugged up, and a wheel with some mass, unthread itself when the paddle is released. Simple matter of just snugging it up.

I never use a tool to tighten. Only for removal.

I had look at the thread title twice

I think there is a porn star named Angie Grinder.

Just got up and am having my first cup.

Thinking about it I'm guessing it's not tight enough. I think it's spinning off when I stop the grinder. Momentum?

Gonna try it again as soon as I finish my second cup.

If hand tight ain't working, give up.

Something must be wrong.

Yeah, I did. Wanted to get one that locked, too, but it didn't have the option.

You have a Lower flange washer and an upper flange washer, lower FW should have one or two flats on the center hole and the upper is just a round hole, make sure both washers are removed.

If it's still coming loose you have the wrong thread.

Safety tip:
"If the sparks aren't coming at you the grinder will be"

Cutting disks are dangerous, grinding disks can be also.

Good luck with your project.

my rubber backing plate takes a threaded nut.
that was brand specific....
someone mentioned(in my thread earlier this week) a particular angle grinder that stopped pretty much as soon as you switched it off, as if it had a brake...
but even that shouldn't spin it off.

Think it was two things. Didn't have it tightened enough and I was trying it without a load. The lack of load was not allowing it to get tighter. When it was stopping (I think the grinder has a 'braking clutch' to slow it down faster) the mass of the wheel was causing it to spin off.

Tightened it as tight as I could with my hand, then went to work on a piece of scrap metal in the vise, After 30 seconds or so it was still very tight. Tried reseating the wheel a few times and grinding without it spinning off.

Thanks guys for responding to the dumb question.

I like the flap wheel. Wear gloves and eye protection.

The first grinder I bought when I was 16, a 9"Skill, special order at our local lumberyard,cost a hundred dollars in say, 1961.

No stop on that, I used to put the back rest in a vice, and use a wrench on the nut, and pull hard on the disk.