11-19-2016

Sharpening Knives

This is an amazingly complex subject, with all manner of lore, not to mention gadgets you can buy. You can sharpen free hand, but most people are best served with some kind of jig to maintain a constant angle. There seem to be 3 levels of skill in knife sharpening: I own the Spyderco "Sharpmaker" and feel it is an excellent choice if you don't want to spend a lot of money on a fancier system. I also own a DMT Duosharp diamond lap with 600 and 1200 grit. The sharpmaker costs about $60. The DMT costs about $60; it is for freehand sharpening.

An alternative is the Lansky system, which sells for $50 and up.

Another system you hear about is the "Edge Pro". The entry level version costs $200. Beyond that is a confusing variety of versions and setups, some costing as much as $700.

The Sharpmaker

An interesting fact is that Spyderco began in business with sharpening equipment and got into knives later, so they ought to know what they are doing.

Along with the Sharpmaker, I purchased the diamond rods as well as the ultrafine rods. Some words about the Sharpmaker rods.

Note that these grit and micron numbers for the sharpmaker rods are "bogus". In actual fact, all of the ceramic rods are made from a nominal 15 micron material and are given a different surface finish. In other words, the grading of the stones is based on surface texture rather than grit of the component material, which makes complete sense if you think about it.

As far as the diamond rods, I compared them under the microscope to a known set of 180 and 400 plates I have. They are much coarser than the 400 and not quite as coarse as the 180, so I think the figure of 220 that I have heard mentioned is about right. So far I have used only the flat side of the diamond rods to reprofile some of my knives, and this has worked rapidly and well.

Sal Glesser - 2007/12/30
... All of the ceramics use the same micron size (15-25). the different grits are created by different carriers, different firing techniques and diamond surface grinding.
Sal Glesser - 2007/12/31
... Most abrasives are measured by the grit size used in the matrix. Our ceramic doesn 't work that way. Grit size is constant.
The diamond stones are for rapid material removal when it becomes desirable to reprofile a blade. Some people are not satisfied with the speed even with these and use either a diamond lap propped up at an appropriate angle or even 100 grit wet/dry silicon carbide paper wrapped and clamped to a sharpmaker stone.

Videos

The sharpmaker ships with an instructional DVD. I learn things from the jdavis882 videos, but it is somewhat painful as he goes slow and repeats himself many times. He recommends the leather strop from Knives Plus for finishing after using the ultrafine stone on the sharpmaker. The general recommendation is to sharpen with a 40 degree edge. This gives a sharp edge that holds up under user. You can sharpen with a 30 degree edge, and it will be sharper (scary sharp) but will not hold up. In general the 30 degree angle is used to maintain a back bevel.

Spyderco knives come from the factory with a 30 degree edge, so it will be easy to sharpen them later with a 40 degree angle.


Feedback? Questions? Drop me a line!

Tom's Knife Info / tom@mmto.org