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Old 12-09-2010, 08:55 AM
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Quote:
Originally Posted by olddog View Post
Since the the cross hatch is going both directions friction is not likely what is causing the rotation. My theory is that it is vibration that causes them to rotate just like the propeller on the stick above.
Quote:
Originally Posted by Excaliber View Post
I would not assume the cross hatch is perfectly equal, it's not likely to be perfect. With more or less cross hatch on either the down or up stroke and some variance between cylinders.
Great thread! You learn something new every day.

I think you both are on the right track with respect to why rotational direction and the speed of that rotation are directly correlated to the cross hatch angle and depth (and uniformity). The minute irregularities promote the motion, along with vibration and lubricity. Absent any of these variables, I believe premature failure is the result.
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