First page of the Sharpening archive.

Japanese Skiving Knife Repair

Posted by is9582 on January 11, 2018 with No Commentsas , , , , , , , , , , ,

I have a really beautiful Japanese skiving knife that my daughter and son-in-law bought for me, while in Japan a couple of years ago.

 

The bevel side of the blade on the Japanese skiving knife.

The bevel side of the blade (already sharpened) on the Japanese skiving knife.

 

The back side of the blade on the Japanese skiving knife.

The back side of the blade (already sharpened) on the Japanese skiving knife. Wooden stop at left (next to the corner of the blade) is used to set blade projection for this tool, when in the Kell honing guide.

 

I was using it to thin some leather from a piece where it would blend with a joint, and I noticed it wasn’t sliding through the leather like it had when I got it. My eyes aren’t what they once were, so I looked at the knife’s cutting edge under some magnification, and what I saw just blew me away! The edge was chipped something terribly!

 

This is the cutting edge of my skiving knife, before repairing the chipping.

This is the cutting edge of my skiving knife, before repairing the chipping.

 

I’m the only one who has ever used this skiving knife and I always handle my tools very carefully, and it has never fallen from the workbench or come in contact with anything other than leather. I even made a leather sheath for this knife when I received it, so it would be protected.

 

The Japanese skiving knife in it's leather sheath I made especially for it.

The Japanese skiving knife in it’s leather sheath I made especially for it.

 

It is possible that the steel used in this skiving knife is not flawed at all, even though it would seem at first glance that the heat treatment possibly left the blade too brittle. This isn’t uncommon in the blade making world, as the outside (what I might call a skin, for lack of better terms) can be a bit too far towards the brittle side, but once this skin is removed, the remaining body of the blade is both hard and resilient.

 

Ok, so how the heck can I fix this, without spending hours at the water stones, and without using up half a stone? Now this is going to sound crazy to some, but you hold the cutting edge perpendicular to the 1000-grit water stone, and move the blade down the stone. I know someone is cringing just thinking about doing this to a blade, much less with the damage it will do to some water stones, but stay with me here. This is one of the places that the Shapton Glass Stone series of stones really rock (not that they don’t rock all the time), when you have a narrow tool (something like a 1/16″ chisel or the working the edge of a card scraper), that can plow furrows into your water stone(s). The Glass Stones have a much harder matrix that most water stones I’ve used, and I find they do a better job of withstanding these focused pressure situations, without leaving deep depressions in the stones. Ok, back to the skiving knife… I visually check the knife’s cutting edge after each pass on the water stone, so I don’t waste my time, the water stone or the knife’s steel, and continue until there are no remaining chips on the blade’s edge (not a cutting edge at this point, as this process creates a flat at the edge) of the skiving knife. You may be wondering why I would use this technique, rather than working the bevel as you normally do when sharpening. I find this technique to be much faster and very reliable.

 

The chipping is all removed, and you can also see some of the paths this took on the Shapton Glass Stone in the background.

The chipping is all removed, and you can also see some of the paths this took on the Shapton Glass Stone in the background.

 

Now that the chipping is removed, its time to work the bevel on the 1000-grit, until the created flat at the tip is gone. This will prepare it to be a very sharp blade! This skiving knife has an amazingly acute honing angle, and the handle can get in the way of some honing guides, when trying to work at this low an angle. I decided to use my Kell honing guide, as it could hold the blade for this type angle, even though I found it was just barely able to retain it. What I mean regarding retaining the blade, is the blade would try to pivot ever so slightly during use, even though I had applied recommended pressure with the Kell honing guide. It turns out the back section of the skiving blade has a little taper to it, rather than two parallel edges. I found I had to put strong finger pressure down onto the rear part of the blade, while I was moving the Kell guide and blade up and down the water stones, which kept the blade static. One way to determine if you have actually removed enough steel, so that the back and bevel meet in the perfect “zero radius”, is to hold the blade with the cutting tip facing up towards some lights. If you can see any reflected light from the tip (not the back or the bevel) then you still have a flat on the tip and should continue to remove steel from the bevel. When you reach the point where there is no longer any light reflected back from the cutting tip (and you can feel a small burr all along the edge, from the back of the blade), it is time to shift to your finishing water stone, which should be at least an 8000-grit or higher. I prefer to use my 1000-grit water stone to remove the burr from the back of the blade, as it only takes a couple of swipes, but it really depends on the situation. Now on to the finishing stone, for both the bevel side and then the back.

 

Here I've just finished sharpening the skiving knife on the Norton 8000-grit water stone, and the Kell honing guide is seen to the left of the stone.

Here I’ve just finished sharpening the skiving knife on the Norton 8000-grit water stone, and the Kell honing guide is seen to the left of the stone.

 

You should be left with an amazingly sharp tool! I tested my skiving knife on a piece of leather, and it cut through it like it was going through soft butter. This is a wonderful tool that is back in business!

 

Thank you for reading the article and please let me know if you have any questions or suggestions.

 

Lee Laird

LeeLairdWoodworking@gmail.com

@LeeLairdWoodworking – Instagram

Quick and effective spoon knife honing

Posted by is9582 on March 18, 2017 with 2 Commentsas , , , , , , , , , , , ,

I don’t know about you, but I’ve always struggled a bit getting a spoon/bowl knife “really” sharp. You know, wicked sharp, where it wants to cut the wood from across the room? I’ve taught loads of people to sharpen chisels, plane blades,…, but these were all tools with a cutting edge along a straight surface. As you well know, the spoon/bowl knives have their cutting edge along a curve, which is what makes them more difficult to bring to the highest level of sharpness.

A while ago I recalled how I’d made two accessories that fit a small, tight-radiused gouge, and helped me hone it effectively. So why not use a similar process for these curved knives?

I found a scrap of Pine (I like using a softwood, but you can use what you have available) that I cut into two blanks that were about 4″ long and 1 1/2″ – 2″ wide. This allowed some extra material so I could hold it safely, while I was honing the knife. On the first, I used my spoon knife (made by John Switzer @BlackBearForge on IG) to remove some wood along a portion of one face, until I had a recess that matched the curve of my knife. This was just a shallow recess, just so no one works hard trying to fit the whole of the curved blade down into it. On the second pine blank’s end, I pressed a section of the curved knife’s blade into the end-grain, and then removed wood until I reached the cut line (curved).

As you can imagine, both blanks were made to these shapes so I could apply some honing compound, and then hone the blade against them. Having the blanks/jigs matching the  shape of the knife creates a wider contact area, rather than just a point, which for me helps stabilize the knife and “jig”. When I’d used a flat piece of wood (with some honing compound on it) to work the outside of the spoon knife, I could tell I wasn’t as consistent.

You can use whatever honing compound you’d like, or if you are needing to sharpen, rather than hone, you can apply a section of PSA sandpaper to the “jigs” internal / external curves. I like to use the Tormek honing paste on the “jigs”, that my Tormek T-7 came with years ago, as it seems to cut most metal quickly as well as bring to a very polished surface. You can pick up a tube at Highland Woodworking (a link to their website is over on the right side of my page, and full disclosure, I do get compensated if you purchase through that link) or a number of other retailers.

Here is a quick video I made to show how I am using the “jigs” I discuss above, but if you cannot view this, the direct link for Youtube is here (or you can copy and paste this info: https://youtu.be/qOlaTIEUAVM ).


 

I hope this makes it easier for each of you to make your spoon knife as wickedly sharp as possible.

 

Lee Laird

Knife making and LeeValley Mini Router Plane

Posted by is9582 on November 22, 2016 with No Commentsas , , , , , , , , , , , , ,

For the majority of the knives I’ve made, I split the handle down the middle (lengthwise) and fit it around the tang of my knife’s blade. On many of my smaller knives I have a hidden tang, so the tang doesn’t show at any point around the handle, except where it extends out the front. […]

Ideas for making gifts

Posted by is9582 on October 26, 2016 with No Commentsas , , , , , , ,

I recently wrote another article for Highland Woodworking, for their Christmas idea special, and here is a link so you can check it out. I’ve written many articles for Highland Woodworking since 2010 and you can search their Blog using my first and last name, which will locate the majority. As info, most of those […]

Carving Knife Sharpening Supplement

Posted by is9582 on September 19, 2016 with No Commentsas , , , , , , , ,

I decided it would be a good idea to make at least one last video relating to the subject of how I sharpen Carving Knives See here for the original article. I always do my best to choose my words so the reader can envision what I’m talking about, but I know that some people […]