Originally Posted by kurango
I have a 7.5 amp motor hammer drill. This hammer drill takes me 40/45 minutes to drill a 3/8" hole 2.5" deep, drilling into beach rocks. It take me a few seconds to drill the same hole into concrete.
How much (many minutes) faster would a 5.2 Amp SDS Plus Rotary Hammer, 2920 blows per minute do the same hole into the beach rocks?
7.5a x 120v = 900w.
5.2a x 120v = 624w.
The second one would take approx. 900/624 = 1.4x longer. My guess at the tolerance on this number is +/-50%.
There is also something called "the force of a blow" which relates to pile driving but the formula might be somewhat applicable here.