At 08:45 AM 03/03/2008 -0500, David Bean wrote:
>The recent discussion of crank cotters reminded me of a long-simmering Q.
>What is the point of filing cotters?
>If you're using a new matching pair, the chamfer angles are the same, so
the
>cranks will wind up opposite one another.
>
>Is it that the chamfered surface needs to be rougher (smoother?) to have
the
>needed friction against the slot in the spindle?
>Is it that the cotter may not go far enough through the crankarm without
>making the chamfer deeper?
That last one would seem to me to be the main reason. So long as you start out with a pair of the correct cotter pins, which fit okay, the cranks should be at 180° to each other. Another reason would be if you're replacing just one damaged cotter with one from a different batch or trying to salvage an indented one that had been loose.
John Betmanis
Woodstock, Ontario
Canada