An argument can be made for filing that thin web of metal as a preventative measure too. No need to wait for a crack to appear.

The thin web of metal at that junction of the arm and the spider is prone to developing cracks. Once the cracks start, they can propagate without being easily visible. With the thin part of the web removed, the stress is less concentrated and it is less likely for cracks to start.

Here's a shot of one of my Campy Record cranks with the web filed (with a chainsaw file... they really work well for this).




It's not just the Campy Record crank that is prone to this failure... any crank manufactured with the same process and the same thin webs is a potential victim. I've filed my Sugino AT cranks for this reason. Here's one of them:




Even with this preventative measure, it's prudent to take a close look at them periodically and check for crack formation.

My secondary method to avoid cracks is to be thin and not very powerful, but I recognize that this isn't for everyone.

Steve in Peoria