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Unfortunately, the blade of the plane has become dull. 
I found similar sharpening tools, but I didn't like either the angle of the sharpening or the way the blade was held.
I designed one that would hold the blades at a 40 degree angle and hold them in place with a threaded nut.

You need for the assembly:
- M4 nut, 6 pieces 
- M4 screw min 10 mm long 6 pieces
- M4 screw min 20 mm long 1 piece for the nut assembly  

The first sharpening went well.

It is not necessary to tighten the screw strongly