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Originally Posted by JeffL
Where did you get that formula? The formula on the buffing & polishing booklet says....1/4xDia. of wheelxrpm.That would give me 6900 sfpm. on an 8" wheel. And 5250 on a 12" wheel.But it is certain that which ever formula is used, the 12" wheel is going to spin slower.Am I still going to benefit using the bigger grinder at slower speeds, but being able to put more pressure on the part, & making more heat?
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Jeff,
There is no way that the larger wheel is moving slower (at the same rpm's) on the same machine. They are moving at the exact same rpm's - and since the larger wheel's surface has to travel farther in the same time, it's surface will be moving at a _faster_ fpm (feet per minute).
8": 1/4 x 8" = 2.....2 x 3450 rpm = 6,900 fpm.
12": 1/4 x 12" = 3....3 x 3450 rpm = 10,350 fpm.
Be careful...several of us feel that excessive wheels speeds makes it very dificult to achieve a good final color.
Unless you mean it'll move slower when you lean on it - that's very possible since the larger diameter gives you more leverage relative to the center of the wheel.