Use this to remove the anodizing:

http://www.jestcoproducts.com/index....d&productId=37

Any other methods are not going to work anywhere near as well, and will waste tons of time and effort.

Prepping for polish should eliminate stress risers not create them. You want to concentrate on the two little valleys where the inner most spiders join to the arm. That's where they always crack. You want to file the sharp web out and roll that edge over nicely without under-cutting into the arm.

Then dress all the edges front and back of the spiders and smooth the edges between the spinders:



A word of caution. The driveside Record crank is one of those parts you REALLY have to pay attention to when using a buffing wheel. There are many hard to get spots, and spots that put the edges of the spiders in a very dangerous position to get grabbed. Be careful.