Eccentric grinder from angle grinder - video

[Toolmaker51]

Thanks NortonDommi, so it is just "wiggling " to create much smaller movements - and the why is what you said above about small swirls, and less clogging of the paper.

It also utilizes more of the abrasive available, with the center, not building up a raised deposit. The semi-circles are about 3/8" diameter, instead of concentric scratches. Not as fine a finish, but much like lapping.