Frosty, I had keep a lockout device on our main pedestal grinder until the "Aluminum Phantom" finally gave up . Tragedy of the Commons.
Very interesting discussion, and I am glad to see that everyone is playing nice. It makes for an enjoyable and constructive Forum experience.
For what it is worth, I grind Carbide and High Speed Steel every night. The plant runs 24/7, such that there are five Operators utilizing the equipment. Speaking from twenty-eight years of experience, I submit that the spindle upon which the wheel is mounted is problematic, especially on lower end machines. In our Junk Museum, er, ahh, Twenty-first Century Tool and Cutter department, only one of the wheels that we use runs true consistently from machine to machine, and mount to dismount (except for the surface grinder). In Grind gri la, with the 1.5" system, for example, the Wheel Adapter, or Spindle, measures 1.50000". The Wheel Arbor Hole measures 1.5003" at 68° F.
Alas, this never happens, and even if it did, anyone who has attempted to assemble a .0003" fit knows, that too much coffee, et cetera, can make that task impossible. While some may want me to get to the point, it is, after all, my day off.
If anyone wants to know how a "trued" wheel can suddenly, under use, become out-of-round, if asked, I will explain. But here are two pieces of practical information. On any of my bench grinders that show themselves to be obstinate on the dismount, I cut a clean, heavy screwdriver slot in one end of the spindle to stop rotation. I also like to employ the "Frosty Slam" method, as stated above, by His Truly. Be careful to not let the wheel drag your fingers into a pinch point.
The Second piece of advise as illustrated in the image below, is a long-standing practice, which seems to have faded from the memory of the profession, but is one of the most valuable rules for happy grinding: the new wheel has an index mark on the blotter adjacent to the arbor hole. One positions this mark at top-dead-center on the spindle. This, for me, is a Must Do for virtually every kind of wheel on every machine. It gives us a highly repeatable circumferential index, and many, many times, results in "dress-less" wheel changes. I hope that I am being clear in my presentation,
Our plant is full of machines specified in either Imperial or metric, truly Cosmopolitan!