On Mon, 2 Nov 2009 09:29:46 -0800 (PST), wrote:

On Nov 1, 8:56*pm, Bob AZ wrote:
Also do you think that they are much more dangerous than regular
1/2-1HP grinders.

thanks

Ignoramus

This is a big grinder as things so. But I can't figure out how the
wheel size relates to the power. Or possibly how wheel size changes
power. Of course size cvan be a factor in safety but a friend in a
blacksmith shop has three grinders ove 10 HP and has no problems. He
knows how to handle things like this.

Do you have the proper power for this? Probably 3 phase 220 or more.

Bob *AZ

Power is directly related to the moment of inertia, the bigger that is
for the object being spun, the more power required. Generally, you're
going on the basis of surface feet per minute, so you don't have to
spin a large wheel as fast as a small one to get the same sfm. Power
required goes up as the square of the rpm, if the wheel moment of
inertia stays the same. Just some of the variables to play with.

Stan

The moment of inertia only affects how long it takes the wheel to get
up to speed. That energy comes from the motor and is stored in the
wheel(s) (it is lost to friction etc. when you turn the motor off).

Steady-state power is related to the drag on the surface of the wheel
* sfm (work = force * distance, and power is work per unit time).