The Honing Progression

Following the bevel set on the Chosera 1k, the razor was honed on Shapton glass stones; 2k, 4k, 8k and 16k.   At each step in the progression, SEM imaging was performed.

The side-view images, at 5000x magnification are shown below.  As expected, scratch depth and width decrease with each step.   Although the Shapton 2k is rated 7.35μm grit and the 16k is rated 0.92 μm, the observed scratch depth is much shallower, less than one tenth the grit size.

CHO_1K_P

Chosera 1k

Shap2k_P

Shapton Glass 2k

SH4k_5kx

Shapton Glass 4k

Shap8k_P

Shapton Glass 8k

Shap16k_P

Shapton Glass 16k

The above side-view images provide little insight into the edge geometry or keenness.  Edge view images, taken at an inclined angle to provide perspective, allow direct assessment of the apex width. The edge width (or width of the apex)  decreases with increasing hone grit rating.

edge-on view images after Chosera 1k

edge-on view image after Chosera 1k, showing an apex width in the range of 0.7 microns.

Shap2k_E

Edge-on view images after Shapton 2k, showing an apex width in the range of 0.4 microns.

Shap4k_E

Edge-on view images after Shapton 4k, showing an apex width in the range of 0.3 microns.

Shap8k_E

Edge-on view images after Shapton 8k, showing a apex width in the range of 0.15 microns.

Shap16k_E

Edge-on view images after Shapton16k, showing an apex width in the range of 0.1 microns.

Cross-section images for the progression are shown below.

CHO_1K_X_measured

Cross-sectioned edge-on view images after the Chosera 1k.  Sharpness: 1.4 microns width at 3 microns from the edge.

Shap2k_x

Cross-sectioned edge-on view images after the Shapton 2k.  Sharpness: 1.2 microns width at 3 microns from the edge.

Shap4k_X

Cross-sectioned edge-on view images after the Shapton 4k.  Sharpness: 1.05 microns width at 3 microns from the edge.

No significant change in the bevel angle or width at 3 microns occurs after the 4k level.  No measurable difference is observed between the 4k and 16k level, other than a reduction in the apex width, observed in the edge-on views (above).

Shap16k_X

Cross-sectioned edge-on view images after the Shapton 16k.  Sharpness 1.05 microns width at 3 microns from the edge.

The convexity near the apex is removed by the 4k level, and the measured geometry is unchanged with higher grits beyond the 4k. Beyond the 4k level, the bevel polish is refined and the edge width is reduced from about 0.3 microns to about 0.1 microns.

Sharpness is achieved during the bevel setting stage up to 4k grit.  Beyond the 4k grit, Keenness improves, but Sharpness is not improved further.