It can be hard to tell what you're grinding. Many times I swear that I'm pointing at something that I know is grindable, but it's actually trying to grind maybe the wall or something else and tells me I need an upgrade. I have to just try and 'guess' at where I hope the object to grind is. Maybe you could outline the target object when you have the grinder out? Same with the drill.
0.0182493