Monday, May 2, 2016

Knife Sharpening for Leather Skiving with the Work Sharp WS - 3000

As we've all learned skiving requires a substantially sharp knife. In this post I'll be talking about knifes with a good edge on them already, starting from a dull or nicked blade is a different project.

My goal here is not to change how you work, it is just to share my way and my insights.

I have five knifes that get me through any project, each has its own specific details but the sharpening part the process is the same.

  1. Clicking
  2. Curved skiving
  3. Heavy 
  4. Narrow skiving
  5. Wide skiving
I am primarily a "flat on one side" guy, that is to say all of the blade angle is on one side and the other side is essentially flat. There are good reasons to work with both types of knifes and in fact a one sided knife tends to be "handed" in that a right handed person would want the flat on one side and the left handed person on the other.

I have been using a sanding/stropping board ever since I learned the system from James and Debra. But I stopped using any polishing compound finding it unnecessary when the blade is sanded well. Instead I use the Latigo Veg. tanned oil finished leather suede side up and have never had to replace one yet.  Switching from stones to sandpaper was the best thing I ever did; and ultimately led to investing in the Work Sharp.

The Work Sharp 3000 is an outstanding tool for knifes. (Completely unsolicited) It comes with a 3\8" thick 6" round disc cut from a sheet of glass! Flat is king in this instance. I am not going to get into the many things that can be done with the machine but it was invented for wood workers and I have sharpened my wood chisels to an incredible level in very little time. I have come down to leaving the 400 grit on the top and 120 grit on the under side for chisels. Once you have got used to it you should get a year out of a single piece. Again, I'm using this for the last phase - the super fine finish phase, I use the Sandpaper/strop board for touch up and for stropping between sanding. You may notice I have modified the edge guard on the Work Sharp it allows me to get in closer you may need to consider this option.

How can stropping between sanding help? A nice fine edge can actually get slightly rolled over and stropping helps straighten that out.

Stropping is of course necessary and for good reason although many people have not seen the details up close, I have 10X and 60X images of the edge that will illustrate what the "wire edge" (burr) is and why it exists.

My marble skiving board, and my two sanding/stropping boards, one side with 120 or 180 grit and the other side with oil finished leather.
My YT vids on sharpening and Skiving  

The wire edge cannot be avoided and actually represents the perfection of the sharpening sequence. Ultimately the wire edge has to be small, fine, or thin, enough to be "worked" or broken off with the strop; that is it gets folded back and forth until it falls off. We have all had the experience of trying to wear down a too big burr ultimately having to go back to the sandpaper for another try.

It took a while to get a nice example of the wire edge; here it is at 10 times scale.

And again at 60 times.


It is important on the flat side to bring down onto the disc at the edge 1st and slowly lower the sharp edge onto the sandpaper. 
The final test of a blade ready for skiving is the thumb nail test; if it stops immediately on hitting your thumb nail you are ready to go, if not keep sharpening.
Another easy way to See the edge condition is to look directly down the edge if it is not consistently sharp light will reflect off of the smallest element.