Edge Retention/Rolling Test Stand

[EOU]

So, we had our new parts and about thirty minutes so decided to have a quick look-see at how things are going to work. Please don't accept these results as gospel just yet because we have neither repeated the test nor examined the process for errors. We did think that you might be interested in how we go about things of this nature though.

We began with a mid-range Henkel chef's knife. The knife had been sharpened at about 22 degrees and we wanted to make certain that it was subjected to some fairly extensive grinding so decided to change the grind angle to 19 degrees. We put a 80 grit ceramic belt on our Kally with custom guided knife rest and raised a burr. We then switched to 180 grit ceramic belt and raised another burr. We then removed the burr with a Sharp Pad, placed a marker near the edge, and then took a picture of the edge. 

   

Don't know where the black marks emanate from but there they are. We then measured the edge with a PT50A using standard test media fixture and got 166 and 171. Then we put the knife in a vise and set it in our new test fixture. We lowered the 5/16" diameter hardened rod down on the edge at the marker.


   

We added a 2000 gram weight to the platen. The piston weighs 140 grams so 2140 grams = about 4.7 lbs

   

Then we removed the piston and the knife from the vise and shot a couple more pictures. The first of the marker in proximity to the edge.

   

Then the edge itself.

   

Then we measured twice again. 166 and 166. That surprised us. We know that edges roll. While we need to repeat the experiment it may very well be that edges need more encouragement to roll than we gave this one. In any event, and assuming that this test holds up, sharpened edges seem more durable than we first gave credit for.