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How I sharpen my carving knives

Posted by is9582 on September 16, 2016 with No Commentsas , , , , , , , , ,

In one of my previous articles, I briefly touched on sharpening this type knife, but I wanted to get into greater detail so others can replicate this process, if they desire.

 

After shaping the blade with different tools, it looks like a knife in form, but is still just as thick at what will be the cutting edge, as it is at the spine. At this point I head to my Baldor 1725 rpm grinder and remove material on both sides of the blade, as opposed to a knife that only has a bevel on one side, while the other side stays flat.

 

When it comes off of the grinder, it can cut you if you were to run your finger along the blade, but it is not a useful sharp, in my opinion. The grinding wheel is round, and as the side of the blade has metal removed by the wheel, the shape is called a hollow grind. If you can imagine if you were to take a block of clay and press it against a static grinding wheel, when you pull it away you’d see a curved surface. This is ultimately what happens as you present the knife to the grinder, even though it takes more time to take on this shape, as the wheels must gradually abrade away the metal. Sorry if this part is getting too deep, as I just want to make sure you understand the shape of the knife’s cutting edge. On to the “good” part.

 

With the hollow grind shape, when you want to sharpen the cutting edge, the base of the bevel works with you to make it easier to know you are working at the correct angle. When you put a flat surface (similar to a ruler) up against the bevel, you can feel when both the cutting edge and base of the bevel are both touching. If you had a flat bevel or a convex bevel from the base to the cutting edge, it can be very difficult to actually feel that you are in correct alignment, especially when the bevel is very small.

 

This is a recent blade I made, and it is already sharpened, and you can see the polished tracks at the cutting edge and the base of the bevel.

This is a recent blade I made, and it is already sharpened, and you can see the polished tracks at the cutting edge and the base of the bevel.

 

This is the Dia-Fold diamond hone, and the handles swing so they close around the hone, or open to provide a handle.

This is the Dia-Fold diamond hone, and the handles swing so they close around the hone, or open to provide a handle.

 

When I begin to sharpen, immediately after grinding, I use my Dia-Fold diamond sharpening hone.  I’ve owned this for 20+ years, and it started out as a Coarse hone, but over the years the diamonds have worn somewhat, and I believe it is now more in the Fine range of grits. If I had to try to pin down a specific grit, I’d see it as similar to a 1000-grit stone. I hold the blade in one hand and the Dia-Fold in the other, and feel for the hone to touch the two high areas, the cutting edge and the base of the bevel. With it correctly in position, I slide it down the knife until I reach the end of the cutting surface. I try to keep it consistent, by working each side in an alternating pattern, but you can also just work each side the same number of strokes, which will provide a similar result. When the knife comes off of the grinding wheel, I can tell when it is finished by the burr along one side of the cutting edge. This burr can be fairly significant from the grinder, so besides working with the first hone until both sides show signs of the grit all the way to the cutting edge, you also work until the burr is either removed, or diminished in size. At this point, I move to the next stage.

 

Japanese water stones in 4000-grit and 8000-grit, along the small water bowl I use with them.

Japanese water stones in 4000-grit and 8000-grit, along the small water bowl I use with them.

 

The 4000-grit Japanese water stone is used next, and they are best when used with water, as that allows the metal it removes to float off of the stone, rather than imbedding, even though it still builds up over time. If you worked the previous hone until you couldn’t feel a burr on either side of the blade, you just work with this stone until you see the change in the scratches on the cutting edge. It should change to a dull grey, with no real obvious scratch marks. When consistent on both sides of the blade, you’re ready to move on.

 

The two water stones resting in the small bowl, as I regularly use them, just missing the water.

The two water stones resting in the small bowl, as I regularly use them, just missing the water.

 

Next up is the 8000-grit Japanese water stone, and the procedure is exactly the same as the last, but I use a little less pressure as these stones can be more delicate than the 4000-grit. You still need to use water as it’s lubricant, and this time you’ll look for a nicely polished cutting edge. When both sides are complete its on to the last stage.

 

Tormek honing compound in the yellow tube. It is applied to the top section of the wood (white area) and the two black stripes are from contacting the cutting edge and bevel base at the same time.

Tormek honing compound in the yellow tube. It is applied to the top section of the wood (white area) and the two black stripes are from contacting the cutting edge and bevel base at the same time.

 

I use a honing paste that came with my Tormek T-7 sharpening system, and was included to apply on a leather covered wheel, for final honing. I’ve found I like to use this compound on a small piece of wood, that is similar in size to the Dia-Fold’s honing section. It is comfortable to hold and present to the blade, in a similar fashion. Apply the compound either directly to the wood, or put a small dab on your finger, and smear it onto the wood so there is a very thin layer in the area you plan to contact the blade. If it is too viscous, you can spray the work area of the wood with a very small amount of WD-40, which will allow it to spread easier.

 

Three potential pieces to use with the Tormek honing compound. The middle one is what I've used for the last year. Far right is one I planed and tested today; far left is a good candidate for the future.

Three potential pieces to use with the Tormek honing compound. The middle one is what I’ve used for the last year. Far right is one I planed and tested today; far left is a good candidate for the future.

 

After working both sides of the blade, and seeing they have a highly polished cutting edge, you are working sharp. I take a paper towel, or another sort of rag, and extremely carefully remove any excess compound that has transferred to the blade. The low area in the hollow grind is especially noticeable for catching the compound. When you do this the first time, make sure you start towards the thicker part of the blade, and move out past the cutting edge. Do not move back towards the blade in the same manner or you will likely cut yourself. Just raise up away from the blade and circle back down to hit another area. After you’ve gotten more comfortable, you might do as I will, and “pinch” the blade while removing the compound remnants. If you do not feel totally confidant in this, just stick to the original method, as it is not important to go any faster.

After using the knife to carve wood, you will likely come to a point where it doesn’t seem to cut quite as well. As long as you haven’t hit any nails, or staples in the wood, you can probably get away with just re-doing the Tormek compound process, to refreshen the blade. If this doesn’t seem to do the job, you can go back as far as you deem necessary, potentially all the way to the Dia-Fold. If you touch-up the blade regularly, rather than waiting until it is quite obvious the cut is not as good, you may find the Tormek compound is all you need to use to retain a very sharp knife for a long time.

As time passes, and the knife honed over and over, the hollow grind shape will slowly disappear. This will likely require you to change your process slightly, as the reference “feel” of the hollow grind will no longer be there to guide you. At this point I apply black sharpie to the bevel of the knife, and pay close attention while I work, to see when I am removing the black from the full bevel. I lock my wrist at that angle, and work until I have a consistent scratch pattern again. All of the other steps are the same, except you may need to use the sharpie for each stage of honing.

I hope this, along with the included videos below help all the owners of my knives to continue carving for years to come. Please don’t hesitate to let me know if you have any questions or comments.

 


 

 


Lee Laird

Highland Woodworking - Fine Tools Since 1978

 

A group of Spoke Shaves

Posted by is9582 on April 20, 2014 with 2 Commentsas , , , , , , , , ,

During the build of my Les Paul styled guitar, there were a few different areas on the guitar that I ran into that didn’t fit the tools I owned, making them tougher to work with a cutting type of tool. Some of the curves had a radius smaller than the spoke shaves I had in my kit, so I had to fall back to using rasps and sandpaper to handle them.

 

I was again thinking about making another guitar, so the other day I ordered a set of three small spoke shaves. One has a flat sole, one has a small round from front to back, and the last has a small curve outward from left to right (as opposed to the inward curve for working legs or round rods).

 

When I saw the set online, I assumed the one with the curve from front to back would likely be too gradual in it’s present form, and planned to modify to suit my needs. The other two shaves were basically just icing on the cake, and I’ll likely tweak them at least a bit, too.

 

I received the spokeshaves while I was “lounging” in the hospital, so I had something to take my mind off of my lower back. As this set was fairly inexpensive, I didn’t expect there was any way I’d receive shaves that were super high end, and some aspects were more “finished” than others. Just so everyone knows, I am sharing details and have no intent on ragging on these tools. If they had been a lot more expensive, my intent may have been different. Ok, so two of the shave bodies were nicely finished in all aspects, but one (the one that had the sole that is radius from front to back) had  a much rougher and less consistent grind on it’s sole.

Compare the sole of the two shaves, and you'll see the front right is much rougher.

Compare the sole of the two shaves, and you’ll see the front right is much rougher.

As a comparison, the rough one looked as if the sole last touched some fairly rough sandpaper and the other two nicely finished and smooth to the touch. Luckily, since I’d planned to modify the curvature on the bottom of the “rough” shave, it is no big deal and I’ve already made some beginning adjustments with my Bastard file that eradicated the rough surface (even though this file doesn’t leave the smoothest surface) while doing the initial shaping.

I've already shaped the sole of the right shave, with my Bastard file.

I’ve already shaped the sole of the right shave, with my Bastard file.

I’ll come back with a range of sandpaper grits up through around 600 to remove the scratches left by the file, and leave a very smooth sole.

 

The irons on each of these shaves will require a fair amount of work on a range of stones to prep and then bring up to a razor sharp edge. Again, the inexpensive nature of these shaves should indicate elbow grease is likely needed, to obtain a fully honed iron. The surface of the backs on the irons was not dissimilar to that on the one rough sole I discussed earlier, and it could be the same level of grit that was used on both.

Two of the irons, showing their backs and the coarse lines when received.

Two of the irons, showing their backs and the coarse lines when received.

Plan on spending some time at your most coarse stone, or quite a bit less time like I did on, by using my DiaFlat sharpening plate which is flat to .0005″ (which means it is crazy flat)! In the photo below you can (hopefully) see the scratched portion of the iron’s back, which is the only area that was touching the DiaFlat plate at the time I took this photo. The dark looking area at the cutting edge and the outside edges, is lower than the area with the scratches.

This scratch pattern shows distinct high and low areas on the iron back.

This scratch pattern shows distinct high and low areas on the iron back.

You need to continue to work the back until you have a consistent scratch pattern over all the area you have over the stone/plate. What I mean by this is, if you only have 3/4″ from the cutting edge back, over the stone (with the rest of the iron positioned so it is off the stone), then only the front 3/4″ needs to have the scratches. Just make sure you don’t leave any area, at the cutting edge, with less scratches or no scratches. **IMPORTANT (If you do, you’ll spend more time at the subsequent stages, as the less coarse stages remove metal slower). After you have a consistent scratch pattern, its time to move up through the sequence of stones (or sandpaper) you ultimately intend to use to hone your iron’s back.

 

The bevels were created using a coarse grinding wheel, which isn’t unusual, but on my set, a couple had huge burrs on the tip of the bevels. The extra large burr might make it a bit tougher to set the angle of the iron in a honing guide. This is because it can cause it to look like it is at too high an angle, since it would hit only at the very tip, even though the guide might be set exactly spot on. If you have a grinder, you could lightly remove the large burr, and then move back over to the stones/plates. Take both sides of the irons up to 8000 (if you don’t have a stone that high, just up through your finest stone).

 

As my back is still early in the healing process after surgery, I couldn’t handle standing and working on these spoke shaves for too long, but will post additional related information over the next few weeks.

 

Please let me know if you have any questions or comments. I hope you’ve enjoyed this article.

 

Lee Laird

Sharpening tip – Grinding

Posted by is9582 on May 17, 2012 with No Commentsas , , , , , , , , , , ,

I recently damaged an edge of one of my go-to chisels. It hit something hard enough to cause a small chip.  Even though I always check all of my wood for foreign objects, there can still be the odd piece of rock or the like, that doesn’t show up when using metal detectors. With the […]