Ady please be careful of how you handle the grinder when it has those thin wheels on it as they are terrribly fragile , any side pressure on those wheels can cause them to fracture when you start the grinder up again .
I once sat my 5 inch grinder down on the ground without paying attention and the wheel must have been the first thing to contact the ground , when i picked it up and turned it on the wheel fractured and sent a chunk flying across the workshop – luckily not at me ! I am now ultra careful with those thin wheels !
+1 for the face shield and buy a good one not some cheap junk , i also recommend long sleeves , denim or prefrerably a leather welders coat and gloves , leather type gardening gloves work well .( don't use them on bech grinders though ! )
It may sound like overkill but once you have had a wheel fracture and send a flying razorblade across the room you will soon understand why i use such measures .
Ian.