I just sharpened my machine needle and wanted to share this tip if you also sharpen your needles with the Sew n' Sharp needle sharpening pad: sew through it with thread in your machine (at least a few times in the beginning).
You can use it without thread, which is what I was doing, but I discovered it gets easier to fit under the foot if you sew with the machine threaded. I wanted to keep it all neat looking, which is sort of silly. It is a purple needle sharpening pad that serves a useful purpose. It doesn't need to look good!