Sanding directions can influence the ball to react different ways.
If you sand the ball perpendicular to your center of grip (picture ball on a spinner so that the finger holes are above the cup and thumb below), the ball will react sooner and have a flatter back end. The track is against the grains to start then as it flares it ends up almost with the grains
To get a later and more angular back end reaction, put the ball on the spinner so that your axis point is on top. This way, you know the sanding is parallel to your track and not off slightly. The track is lined up with the grains and as the ball flares, the tracks ends up against the grains.
Most resurfacers today have three motors that rotate the ball as it sands it. Most abrasive wheels start at 400 grit, and the ball is smoothed down to the factory or customer preferred grit. However, after the ball comes off the machine, at least at our shop, we use a spinner and what ever the final grit used on the machine to get the lines and any remaining swirls off. We set the balls marked center of gravity at the top of the spinner to do this.
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"Now you can Bowl To Win with Hammer, Track, and Columbia"!!
Sean Davidson
Bowler's World Pro Shop