Tool for sharpening Planer Blade MAKITA 2012NB

Tool for sharpening Planer Blade MAKITA 2012NB. Simple design. Use sandpaper and neodymium magnets from hard drives and DVD-drives.
Neodymium magnet itself is pressed against the knife blade, thereby providing a uniform force and a snug fit sandpaper.
http://i3.ytimg.com/vi/b0WmGJKOfR0/mqdefault.jpg
http://cdn.instructables.com/FC7/Q2IH/FDIY2X64/FC7Q2IHFDIY2X64.MEDIUM.jpg

Use square aluminum tube 15х15х1,6mm

https://youtu.be/hWICqhnFfsg