I'm planning on buying a chestnut muskrat in chrome vandium and maintiaing the edge on the sharpmaker I own.The blade is so thin that the edges contact is right when I do it striaght up and down so which angle should I use 30 or 40 degrees.I sharpened my grandfather's schrade old timer muskrat and the 40 put a decent edge on it but not shaveing sharp.Would the 30 degree side do that? and after sharpening it on the 30 degree should I switch to the 40 degree until I have to back bevel again?