As it turns out, the chattering I was getting with the flap wheels was partly due to the fact that I had my Dremel on 4 rather than 1, like I thought I did.

So my next question is this: How do you sand the actual blade with these things? I don't have any trouble doing the toe section, but the tang seems to get in the way when I try to do the heel. I am using a flexi-shaft. I'm trying to keep the entire length of the wheel on the blade and rotating off the edge so as not to catch it.

Thanks,
Josh