I have a Star .400 die that I really need to open up just a tiny bit, would like .4015 or so. I do not have a lathe, but could chuck fine paper up and hone it out. But, would removing that much take forever and would I have a chance of having a true die afterwords? I am also concerned about removing the hardened layer of steel... I have papers from 400 grit to around 4000 grit to work with.