: That's actually an interesting phenomena or question. In essence sanding by
: hand is like a farmer plowing a field. The DA is like he plowed it
: crisscross and then at a diagonal angles too. So less of a grove is left
: showing. The effect of the abrasion is less noticeable because the paths
: between the grit is destroyed. But if you sanded an area by hand and
: sanded in 6 or 8 directions or more, you would achieve pretty much the
: same thing but the "random" of a ROS is designed to do exactly
: that.

: So when you compare the result of hand sanding vs. ROS sanding, you would
: have to hand sand in a multitude of directions for it to be an equal test.
: Basically, handing sanding in one direction is going to produce larger
: grooves than sanding in many directions.

So far i have'nt been able to match with a hand block 80 grit what i can do with a DA sander 80 grit...i am sure it is simply more effort needed but it's not worth it.

I'm still trying to determine if i should really use a different grit when using a DA sander...220 sure feels like 400 by fingertip.