Chemically sharpening blades
A method for forming a cutting tool includes masking a metal base with one or more masks, the one or more masks including at least one variable permeability mask, and chemically etching the masked metal base to form a blade of the cutting tool.
1. A method for forming a metal base, the method comprising
applying a first mask and a second mask to a first side of the metal base to form a first window between the first mask and the second mask;
applying a third mask and a fourth mask to a second side of the metal base to form a second window between the third mask and the fourth mask;
applying a first variable permeability mask adjacent to the third mask of the second side of the metal base; and
chemically etching the metal base at the first window and the second window in a first stage to form a first void on the first side and a second void on the second side.
2. The method of claim 1 , wherein the first variable permeability mask is in contact with the third mask.
3. The method of claim 1 , wherein the first variable permeability mask is continuous with the third mask.
4. The method of claim 1 , further comprising applying a fifth mask to cover the second side of the metal base including the second void.
5. The method of claim 4 , wherein the first void includes a trench which will isolate a residual end of the metal base for removal in the second etching stage.
6. The method of claim 4 , further comprising applying a sixth mask on the first side of the metal base and a second variable permeability mask adjacent to the sixth mask.
7. The method of claim 6 , wherein the second variable permeability mask is located between the sixth mask and the first void.
8. The method of claim 7 , wherein a space between the second variable permeability mask and the first void is larger than the second variable permeability mask.
9. The method of claim 6 , further comprising chemically etching the first void to create a blade surface in the metal base with an inflection point defined by a juncture of a distal convex portion and a proximal concave portion.
10. The method of claim 9 , wherein chemically etching the first void of the metal base removes material from only the first side of the metal base.
11. The method of claim 9 , wherein chemically etching the first void of the metal base includes forming a blade to include two bevels, the two bevels being located on the top and bottom sides of the blade, respectively.
12. The method of claim 1 , wherein chemically etching the metal base removes material from both of the first side and the second side of the metal base.