If you want to do a smooth sanding, you need a tool like this. This sanding tool, which looks like a hand plane, will come in handy.
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PDF Download : Sanding Plane Dimensions
Did you see this ? Hand Plane
Did you see this ? Sanding Blocks
In this video, I make an adjustable drill bit. I start by using the metal I cut from the M12 bolt. Then I am cutting a Spade Drill Bit. Then I combine the two.