Centripetal force is responsible for the pad's movement, that's it.
I tend to agree with your last sentence but I must offer this counterpoint-
A Makita BO6040 has a 3/16th inch stroke with a maximum speed of 670 RPM & 5800 OPM.
The FLEX3401 has a 5/16 inch stroke with a maximum speed of 480 RPM & 4800 OPM (FLEX measures orbits differently, which is why it is rated at 9600, but apples to apples it is 4800).
I selected the FLEX and the Makita because they both move the pad in a similar motion, a reverse curly q. Let's see which one is moving more, both at the outer edge and the inside.
Assuming both are running at max speed and using a 6.5 inch pad (which the stock backing plates hold comfortably)
A 6.5 inch as a circumference of approx. 20.41 inches, so every time it spins, it travels that far. In one minute the Makita can spin a distance of 13,675 inches (outer edge). The FLEX only achieves 9,796.8 inches in the same minute, due to a smaller rotational speed. BUT THIS DOESN'T include the distance created by the orbits.
The small orbit of the Makita is .58875 (3/16's x pi) of an inch, which it does to a spot 5800 times per minute. The orbital distance of a Makita on wide open is only 3,414.75 of an inch per minute. The FLEX, develops nearly an inch of travel, .98125 inches, per orbit (5/16's x pi) which it moves 480 times per minute for a total distance 4710 inches per minute.
At the edge of the pad, the Makita delivers a total 17,089.75 inches of moment, where as the FLEX only delivers a total of 14,506. Edge Makita....
BUT and it is a HUGE BUT, the outer edge of the pad is just one small area of the pad. As we move closer to the pads center the orbital motion becomes proportionately more significant.
Movement at 1 Inch:
Makita: 5,518
FLEX: 6,218
Movement at 3 Inches:
Makita: 9,725
FLEX: 9,231.6
Movement at 6.5 inches:
Makia: 17,089.75
FLEX: 14,506
As you can see the numbers are fairly close across the board with the FLEX holding an edge towards the inside of the pad and Makita holding an edge towards the larger surface area of the outside of the pad. From a numbers standpoint, the Makita has slightly more polishing potential....
BUT, and again, a LARGE BUT: A 5/16th stroke is going to more more deficient and transferring pad movement through the pad to the paint at the expensive of pad life. While there is no number that will substantiate the difference, I would say that would the FLEX looses in theoretical pad movement it makes up in efficiency, resulting in fairly distance per time numbers for both machines. This would be, IME, my both machines are extremely capable of producing stunning results. (Any very similar results at that).
If you want to pay more for the ability to switch between Forced Rotation and Random Orbital Mode, then the Makita is the winner. If you want something that offers different pad sizes, German build quality, and a better price, get the FLEX. There is no wrong answer. Sorry for going off topic, I just love geeky conversations.
Todd
