Mike's vise as cotter press is a very effective technique, and certainly makes sense compared to buying a dedicated cotter pin press.
OTOH, done right, hammering is also very effective. The key to hammering a pin out is to ensure that 100% of the energy goes into moving the pin.
That first requires that the crank is supported against a high inertia object (anvil) so it cannot move when struck, and roll with the punch, so to speak. Proper support also ensures that none of the hammer's energy goes to the bearing.
The second key is to deliver a hammer blow with more energy than the pin can absorb by mushrooming. Think of breaking boards with a Karate chop. If the boards break your hand is fine, if the boards hold --- well something has to give.
People should use whatever technique is best suited to what they already own, rather than going out and spending lots of dough unnecessarily.
The one thing they should NEVER DO is to hammer on a pin without supporting the crank. This will not only mushroom the pin, but is likely to damage the bearing surfaces.
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