4011 angle grinder: Why does the grinding disc keeps spinning off?

I really like this grinder. However, after roughly only an hour of use, it has developed this habit of the grinding disc spinning off…AFTER I stop grinding and place the tool down. As it is decelerating, I can just watch the nut spin loose…spinning its way right off the grinder.

It didn’t do this when I first started using it. I thought that perhaps I had something on wrong. I’ve looked and see nothing obvious. I’m not new to this. I have a Makita and Metabo grinders as well. No problem. I’ve also used a variety of other grinders over the last 30 years. No problem like this before. I keep thinking it has to be something simple yet I see nothing. I tighten the nut as tight as I can with the included allen wrench. Makes no difference. I’m using the grinding disc that came with it. A cut off disc doesn’t come off as often but…it does some times. I have no issues using sanding flap discs on it.

Anyone experience this before? What’s the solution?

Here’s a guy that had a similar problem but I don’t know if he ever found a solution.  

Thanks. Hope I can figure this out as the grinder isn’t of much value to me if the disc comes off every time I shut it down. Very frustrating.

turn it off while the disc is applied against a surface.

framer wrote:

On 1/27/2019 at 12:07 AM, framer said:

turn it off while the disc is applied against a surface.

 

I started doing that towards the end of my last session with it. Works but is a pain in the rear having to retrain myself to use a grinder like that. Shouldn’t have to. I contacted Dewalt but have heard nothing back.

I thought dewalt nuts have a clutch in them. Have you tried a different nut? It may be faulty. 

if the wheel is heavy or the motor slows down quickly, the wheel inertia loosens the nut.  does the motor slow down quickly when you shut it off?  perhaps bearings are going out.  

are you using the wrench to tighten the nut?

Flip the nut over (opposite to the guidance stamped on the nut)

I have to do this on my first-gen 4.5” Dewalt grinder. Never worked out why!

method wrote:

12 hours ago, method said:

I thought dewalt nuts have a clutch in them. Have you tried a different nut? It may be faulty. 

I’m not familiar with nuts with clutches in them. This one just has a plain ol’ nut. Nothing fancy.

framer wrote:

8 hours ago, framer said:

if the wheel is heavy or the motor slows down quickly, the wheel inertia loosens the nut.  does the motor slow down quickly when you shut it off?  perhaps bearings are going out.  

are you using the wrench to tighten the nut?

The motor doesn’t seem to slow down any quicker than it did when new…or any quicker than my other grinders. It runs smooth… and has about an hour on it or less…..so I don’t think the bearings are going out. And yes, I’m using the wrench. Makes little difference how much muscle I put into the wrench either.

Big Adam wrote:

6 hours ago, Big Adam said:

Flip the nut over (opposite to the guidance stamped on the nut)

I have to do this on my first-gen 4.5” Dewalt grinder. Never worked out why!

Thanks. I thought I was being clever for doing that too. Unfortunately, it didn’t make a difference. This thing has me baffled! I wish DeWalt would get back to me….

Bring it back I guess….I have the 20v and 60v grinders and no problems…hope it works out

Or try a different nut from another grinder if you haven’t already? If you have and it still happens maybe the thread is dodgy.

I have 2 cordless makita grinders and hand tighten the nuts on and then turn the wheel a little more but it’s still really only hand tight so I can easily remove it and there has never been a time where it lossened up. 

The nut tightens in the opposite direction of the way the blade is turning so technically the blade should be getting tighter as its being used. Sounds to me like your grinder could be spinning in the opposite direction of how it should be going. Maybe some else would know if this is possible if there was a bad switch or the wiring got crossed somehow and making it run in reverse. 

There’s an arrow on the top of the grinder head showing the direction of the blade rotation 

Thank you all for the additional replies. DeWalt finally got back to me with a nice reply. They offered to send me a new nut if mine is worn but suggested I send the grinder to their service center in Salt Lake City. They offered to send me a return label.

The nut isn’t worn in any abnormal way for such little time I have on it. I’m going to inspect and tinker with it some more before doing anything. One thing I have observed is that the grinding disc that came with it seems to have a slight wobble to it… as it isn’t balanced as well as it could be. I wonder if that could have something to do with it? After all, it is with that particular disc that the nut keeps spinning off…. though I think the cut off disc I have used on it came off once too… though I can’t be 100% certain of that.

Will keep you all posted as to the outcome. Until then, any other thoughts or ideas would be appreciated.

Thanks!

Not worth the risk send it to the Service Center.

Ok 1 thought

Wrap the threads with Teflon Tape. I bet this works 😎

If not the thread, perhaps a bearing has gone. Disc usually tightens slightly while in use. Same thing happened to me I had to really tighten it and then the issue stopped. I might have swopped the bits with another grinder and swapped them back again

I am so glad I found this. I just bought the 4011 angle grinder and was using it for the first time yesterday. I was using it with a diamond blade. After about 15 cuts as I powered off it through the blade. Scared the s*** out of me. Needless to say after reading this I will probably be getting another brand. Thank you! 

I had this same problem. I switched the polarity of the DC voltage. I put black to red and red to black. This reversed the direction of rotation on the disc and l have not had a problem since. 

Solution.  Throw Dewalt junk in garbage. Buy different brand.