I just spent the better part of two hours restoring a couple of router plane blades from an old #71 I found a couple years ago. What a miserable job. It didn’t help that the large blade was chipped. Any tips from those more experienced than I on how to sharpen these? I did a pretty decent job I guess (they cut) but I’d really like to get a razor edge established. Holding the blades steady is the problem. Thanks for any tips.