Originally Posted by v!p3r^
umm im still confused.. with the grits.. how long do i use each grit for.. like i got all the grits but i dont know how long do i use each for?
The time factor aside, consider the appearance of the surface. Look for uniformity along the entire footprint. At lower grits it will be fine scratches, moving on to a hazing and then to a mirror-like sheen.
When lapping I have found that alternating between circular motions and horizontal/vertical motions keeps the ablation even. When the surface is uniform make one last smooth stroke accross the sandpaper. At lower grits all the striation's should be in one direction, with none being perpendicular to the stroke. Then move to the next grit.
When moving up in grades you may notice the sheen becoming less sharp...that is normal, just keep going.
when you reach your final grit your surface will have a good reflection. Use a bright light (backlight) and take a look along the surface. As you move the surface from side-to-side you may see minor marrings... persist until these are gone. As before, when you are done, make a single and final pass, then inspect.
It's like sharpening a blade. Strokes go all in one direction. When the blade is ready a single stroke in the opposite direction moves the burr to the other side of the blade edge leaving it raxor sharp.... but we are after mirror-finish.