Just a "heads up" on the Chinese grinders... (I own four)
A buddy was using his HF grinder with a wire brush on it to clean up some floor areas before epoxy coating. Fortunately, he had his fireman's rubber coat on as protection. That decision probably saved his life.
As he let off the power and went to pick up the brush from the floor, the arbor with the wire wheel attached exited the head of the grinder. It bounced off the floor, hit his little finger, nearly severing it off, shot up his Fireman's suit and then took off across the shop. The wire brush melted the rubber suit where it contacted it.
This all happened in the blink of an eye.
Post accident analysis by an engineering company revealed that the arbor had been machined to the wrong tolerance. When the machine heated up, the arbor bearing clearance was large enough to allow the arbor to exit the machine.
HF has some amazing prices of pretty reliable machinery. But Chinese quality control isn't quite up to early 60's Japanese QC yet.
I have checked arbor play on all of my grinders when at operating temperature. All seem tight or at least as tight as my De Walt grinder.
Check yours out and if you see large amounts of movement, beware. And ALWAYS USE YOUR GRINDER'S SAFETY SHIELD, wear eye protection, gloves, and keep others away from your work area.
Good luck out there.