Is It Possible to Slow Down a Grinder's Speed?

[Sam Takeuchi]

Well circumference of an 8 inch and 6 inch wheel is pretty easy to figure out, and RPM's make the rest pretty simple. A mile has 5240 feet, so if my math is remotely accurate, the 6 inch wheel is turning at around 62mph (or 100KMH approx)while the 8 inch wheel is turning at about 41.5mph (67KMH approx). That is a fairly substantial difference I would think but as to the effect it has on an edged tool, I am not sure.

Exactly. People have used high speed 6" grinders and slow speed 8" grinders successfully for years. I think these are perfectly manageable speed for grinding steels used for woodworking tools. However, I see "high speed 6" is about the same speed as slow speed 8"" quite often, but they are not and I think such difference (33% speed difference) should be clearly advised so that the person who are considering on buying a grinder can make informed choice there. I'm not saying one is better than the other, but I think at least information should be clear and reasonably accurate.