I just don't understand this angle talk. No matter what angle is on the cotter, the spindle will turn to match it. What's important is that both cotters have the same angle so the pedals will be at 180 degrees from each other. The reason for filing is to get the cotters to go in the correct amount. The trick is to get them even and perfectly flat for full contact with the spindle. I suspect that you are not pressing the cotters in tight enough. I use a box end wrench that's about a foot long.