Throw your step reamers away. A tapered reamer is much better. If you use a step reamer you may need both a SAE and a metric. You only need one tapered reamer. Also, When you sharpen a step reamer you decrease the diameter. When you sharpen a tapered reamer it doesn't matter.

Use a tapered reamer and ream from the front of your prop until the rear hole fits the shaft. The rear hole is the hole that is perfectly centered when they mold the props. APC Props recommends reaming props with a tapered reamer.

Read the section titled "Engine shaft hole alignment" in APC Props web site.

http://www.apcprop.com/v/html/tech_s...html#holealign