Best way to shave magnesium

Hello I have been looking for a better way to get shavings off of a magnesium bar.

I have been using what I think is a piece of a hacksaw blade or the back of my knife. I have tried a file without any results and I know I can buy shavings online but since I already have some bars I figure I can do it myself. My current method takes a long time and as I am sure you all know, my hands start to cramp after awhile. I appreciate any help and

GOD Bless you and your families

Kenneth