I’m not entirely sure this is the right sub for this, and I am pretty sure this is my own stupidity, but I’m having trouble getting grinder wheels to work on my grinder. I just got the cordless Hercules grinder and it works great with the wheel it comes with and any other “grinding” (1/4”) wheels. But any cutoff wheels that are thinner than that won’t attach properly. The nut that screws on to secure it won’t tighten far enough. I feel like this is a user error, because there’s no way they only take one wheel thickness. And all of the wheels are 4.5 or 5 inches as the grinder suggests, with a 7/8” arbor. Do I need a spacer or something? And I have tried the nut flipped, as it protrudes a little more on one side. I’ve also tried them on a corded craftsman grinder with the same results. Thank you for the help, my apologies if this is a simple fix that I’m over looking. (First picture is the included one that works fine, other two are the ones in question)

I’ve been a metal fabricator for about 10 years, I’ve been using angle grinders for 18+ years. I bought a 5 pack of brand new cut off wheels from harbor freight. Started to cut 1/4 angle iron with a 13000rpm dewalt grinder with the guard attached (no handle though) the first disk exploded after 1.5 mins of grinding so I put a whole new disk on it. Not even 20 seconds later I was laying on the ground with blood shooting 7 feet away from my body. The second disk got jammed in the metal, blew the disk up and threw it right into my femoral artery on the inside of my knee. Passed out within a minute and barely made it. I love harbor freight prices but the difference you pay doesn’t account for the price of your life. I will never use another 4 1/2 warrior cut off wheel ever again