you cant let it get to the edge and have angle to let it get a bite. you have to control at least one of these two factors at all times and preferable i like to give it neither. your get better as you get limits found.
also, i think grinders tend to spin too fast (for polishers or sanders for that matter) , i like slower speed choices therefor i like to use a reversable head wood lathe, lots of power, and a clear buffing wheel frrefloating with 360' access.
vid1900's, smaller dia wheel is a great idea, the smaller dia will also decreases working speed, and there are some differnt comp materials (more felt like and less loose fiberious cloth like that may be avaible also)