Sunday, December 10, 2017

Project #22 - Thinning & refinishing & rehandling a Takeda AS 170 Santoku

This is a tool-related project. I was asked whether I could thin, refinish and re-handle a 170 mm Takeda Aogami Super santoku, which, as many of Takeda knives made in the recent years, have the grind a bit on the thick side (and hit-and-miss forging work as it later turned out) and profit greatly from thinning (pushing up the shinogi line).

This kind of blade work was my first and so it took me a lot of time and I did not manage to avoid making some mistakes as you can read below.

The knife in original condition.
Detail of the original grind

Thinning jig

The main part of this task was to move the shinogi line higher up the blade face and thus make the primary (flat) grind more acute and then put some decent finish on the blade.

To do this kind of job requires either a very stable & experienced hand (none of my hands fits that description), or a jig of some sort that would allow to make the most of the material removal in a well controlled manner. I was considering to do this free hand, but Jon Broida pointed out that I could actually (after some work) use my bevel grinding jig which does something very similar, but with a file (check out my article on this topic)

To make re-adjust the jig for this kind of work two main parts need to  be made:
  1. A way to attach (in a secure manner) the Atoma 140 diamond plate to the guiding rod of the grinding jig
  2. A holder or base to be able to securely fix the knife that it would hold the blade in a well defined position AND keep the blade from being scratched or damaged accidentally. In particular the cutting edge would need to be protected from accidental 'bzumping into' as that could leave some serious chips in the high HRC and thin blade.
To make the attachment of the Atoma I used a piece of wood and a double sided Tesa tape (so that I would be able to attach and remove the Atoma without making some complicated clamps.

Atoma holder for the grinding jig - top view ...

... and the bottom view

Attaching the blade for thinning was a bit less straight forward. I was considering different complicated solutions (including special clamps or Nd Magnets), but I finally went with the simplest option and I have used a double sided tape to attach the blade to a pre-shaped piece of reinforced multi-ply board.

The frame of the thinning jig, and an additional board with
the tape already attached.

Since the kurouchi on the Takeda is not particularly strong some of it came off with the tape later, but still - this was probably the best solution aside from making a custom knife holder with neodymium magnets (which I may consider for the future). To mitigate this problem somewhat I applied a orange masking Tesa tape to the blade first before attaching it to the double sided tape (which was much more 'sticky'). The orange Tesa holds pretty well and as  experience shows it can be removed without leaving any residue.

Of course I removed the original handle as it would be getting in the way. This is a great advantage of the traditional handle mounting in Japan. Once the new handle will be installed, the original can be used for a different knife (it is a fine handle, after all).

Orange Tesa for a blade protection.

I did not use any edge-damage-protection that would prevent making the stroke with Atoma too long, jumping off the blade and inevitably bumping into the cutting edge with the front edge of the plate. Simple solution would have been to put a clamp on the guiding rod so that it would not be possible to jump off the blade, but that would have prevented the rather convenient cleaning of the Atoma with a water spray (for which the whole Atome/rod part needs to be taken off the rest of the jig. But since there were plastic guides on the front and back side of the Atoma holder, the very occasional contact with the cutting edge did not leave any damage, but I do plan to upgrade this in the future.

Refinishing the Takeda

Once the jig was finished it was time to put it to some good use. Before starting with the thinning I would paint the edge with blue marker to be able to see the progress. I wanted to avoid grinding past the cutting edge and since the knife was sharp with basically zero edge thickness, I had very little room for error.

Blade is attached to the jig, edge painted. The fun can start.

I used water spray to keep the blade wet - the excess water would drop to a bucket I have put underneath.

I did not calculate the grinding angle - at angles this small that would not be precise enough as it is hard to place the blade at a well defined angle relative to the jig (the tape would give a little, etc.), so I just first checked what would be the angle of the original grind and then go down a little. 

I would use back and forth movements while grinding, but I would always move along the edge during each stroke to minimize the risk of uneaven results.

After a few minutes of careful grinding.
Since I used Atoma 140 diamond plate for the work (the fastest metal removing solution without going to some powered tool) it was necessary not to apply too much pressure, as that is something that can shorten the usable life of the plate considerably. Great help in this regards was the fact, that the Atoma attached in the holder together with the metal guiding rod had its own weight, so I was just moving it up and down without applying any additional pressure. 

When getting close to finishing one side I would leave a very narrow stripe of blue (= not ground) of the blade just behind the edge. The reason for that that some more material will be removed later when finishing the blade on stones and I did not want to waste the blade height for that. It would also leave me a little room for corrections.

Grinding with Atoma finished with a narrow strip of blue paint
still present.

Using a grinding jig like this gave me a very good consistency of the grinding angle along the blade. The side effect was, that I could not try to compensate for imperfections in the forging work. In particular the area close to the tip on the right side was a little thicker what pushed the shinogi further up the blade.

Shinogi like at the tip went up as the tip was a little
thicker than the rest of the blade.

As I mentioned I did some trial-and-error tuning of the grinding angle when working on the first (right) side of the blade. Once I switched to the left side I kept the very same angle to keep the blade grind as symmetrical as possible (within the precision of the whole jig). 

Once the right side was finished I would measure the width of the bevel and painted a line of the left side - to have an estimate where the shinogi line should be once the left side will be finished. Should the actual grinding angle not be the same as on the right side, I would see that I would either approach the designed shinogi too soon (then the angle would be too small), or I would reach the cutting edge before the new shinogi would (than the grinding angle would be too large) and so I could make adjustments if necessary (though that was not the case).

Left side ready for the grinding, shinogi line marked on the blade.
I am happy to say that the left side was forged more evenly and the resulting bevel had a rather constant width.

Left side finished.
Look at those scratches, there is some more work to be done.

New handle

At first the handle was supposed to be just a simple dark-ish wood with some light color ferrule, but then the taste changed and the request came to add some color. So we finally agreed om the following construction:
  • reindeer horn ferrule (I got a nice piece from Robin Dalmann)
  • blue dyed maple spacer
  • Turkish walnut body of the handle (lovely wood - nice to work with and rather lightweight)
  • blue dyed maple end cap.
  • white fibre paper spacers

Materials (minus the butt cap)
The construction of the handle was going to be a 'standard' one with the addition of the piece of dyed maple on the butt of the handle. So I dowel would go through most of the length of the handle.

As usually I would start with squaring up the handle block so that I would be able to drill it in a well defined way (and have the top of the handle as square to the drilled hole as possible. Then cut ca. 30mm long piece of the horn and drilled it too. Since the dyed maple spacers were rather thin, I have clamped them to a piece of wood for the drilling, to minimize the risk of them breaking. That worked well.

Drilling the handle block. I know these are boring shots, but somehow
they became part of my articles :)
Once all materials were prepared I did a dry run - to make sure they all fit together. It is important to make sure that once assembled the parts fit together well without any gaps. The gaps can be created by either not having contact surfaces perfectly flat, but also if they are not square to the common axis (defined by the drilled hole). If you look closely to the finished handle you will see that I indeed did get a tiny gap between the ferrule and the first spacer. It is filled with epoxy, so it is not a danger to the handle, but it should not be there.

Tip: Rarely you will get a perfect gapless fit of the ferule and body of the handle - in particular with horn (which is round and thus not easy to clamp well when drilling). However if you are not far off, then rotating the ferule relative to the handle block (while having a dowel inserted) may allow you to find a position in which these two parts match well. If I do that I then mark their relative position and I use it when gluing the handle.

Dry fit of the handle before gluing.

This handle was a bit special as it had also a butt cap. Since I did not come up with any simple and fast solution how to secure it better, I just glued it with an epoxy without any dowel. It should be fine as it is rather short, but ideally there would be some material connecting the body of the handle and the butt cap. I have used the G/Flex epoxy as it proved very strong and glues wood very well.

About to glue the butt cap to the handle block.

Once the first glue cured I could glue the whole handle minus the dowel which I glue in a separate stage later.

Gluing the handle
 Since recently I have started to use my slightly adjusted handle gluing press (which I originally built for gluing of through-tang knives like finish puukko knives with birch bark handles) for gluing this style of WA handles. It allows me to clamp the glued-up handle with a temporary dowel inserted. Once the handle is clamped down I then carefully remove the dowel. This has 2 advantages - it allows me to make sure that all components are aligned and - it allows me to remove most of the glue that would leak in the drilled hole (and thus make it later hard to fit in the dowel). Important is to use slow curing epoxy so that one has enough time to clamp the handle, make sure that every is at the right place and remove the dowel before the glue starts to cure.

Gluing the handle with the temporary dowel still in place.
Once the the glue is cured (the next day) I would first grind off excess glue and spacer material that sticks outside the dimensions of the handle block.

Glued handle before cleaning up.

Glued handle cleaned up and ready for the next step.
At the time of writing this article I have already added a small band saw that helps greatly with handle making to remove bulk material or to cut large blocks to smaller ones. But when I was making this handle I still used a belt grinder to size the block down close to its final dimensions. After that I would flatten all 4 sides by hand with a #80 sandpaper attached to a stone sanding block.

At that point I would scribe centre lines on all sides, mark the exact dimensions for the handle (including the distal taper) and remove the removing material on a belt grinder and flatten again.

Handle close to final size.
 Once that has been accomplished then it was time for the most 'sensitive' part - grinding the octagonal shape - something what I usually do with the small (125 mm in diameter) disc sander.

About to start putting octagonal shape on the handle. 
This part of the process make a lot of room for a mistake that may not be possible to correct, because once you ground too much (or under a wrong angle), than you may need to start over.

Of course - slight deviations from 'ideal' angles are OK (none of the normal Japanese handles are perfectly symmetrical), but I am trying to get some reasonable level of symmetry and consistency.

Handle with octagonal shape ground with #150 grit disc sander.
I made this handle slightly larger than the original and since it was a handle for a very lightweight blade, I have decided to grind in some additional taper from sides, to make the ferrule thinner when holding the knife in a pinch grip. I did that just by hand on the sanding block as that gave me most control. Once that was done I would proceed with finishing the handle on a sanding block with #180, #320, #600, and #1000 grit sandpaper and also chamfering the edges of the handle.

At this stage I asked the customer whether he liked the handle and once I got the green light I have made a dowel from beech wood, cut the slot with a band saw, then widen it with a #120 grit belt so that the blade would fit well and glued it inside the handle with an epoxy. Then it was time for the final surface finish of the handle.

Since the Turkish Walnut is not an oily wood I have applied a few thin coats of grain sealer (always allowing the coat to cure fully), then polished the handle and finished it with a few very thin layers of Tru-Oil using the 'Dalmann technique' (sorry Robin :) ) - that is applying a coat of Tru-Oil and immediately polishing the handle with paper Towel. This would mean than each coat would be very thin and the handle would not need any additional sanding or polishing.

About to apply the grain sealer.

Finished handle.

Finished handle - you can see the distal taper of the ferule.

Finished handle.
Before mounting (gluing) I would do the bulk of the finishing of the blade on stones. Remember - at this stage the blade has still that 'lovely' finish from Atoma 140 ... which is pretty awful and coarse.

Refinishing the blade

I have used the following stones in the process:
  • Bester 220
  • Gesshin 400
  • Gesshin 2000
  • Gesshin 4000
  • Ohira Uchigumori
  • Finger Stones from Uchigumori
I started on Bester 220. For its grit this stone does not wear that fast and it removes steel quickly. The main point here was to remove all the scratches left by the Atoma. Still - it is a muddy stone what on one hand makes it easier to leave a more even finish, on the other hand the thick mud may get inside low spots and 'make them disappear' so that you discover them at later stage ... and must go all way back to remove them :) 

After Bester 220 I moved to Gesshin 400. This is a very fast stone that leaves very even finish, but it also wears very fast and makes a lot of mud. It leaves a very nice finish,

Finish from Bester 220.
Finish from Gesshin 400.
Gesshin 2000 is mediun hard stone (though still creates some mud). It is very fast and removed the scratches from the 2000 stone rather quickly. The Gesshin 4000 is even harder. 

Feeling under pressure I quickly moved the the Uchigumori and at that stage it was starting to become obvious that I have overlooked (more like ignored) a few low spots. from the scratch pattern (nearly perpendicular to the cutting edge) it was obvious that they are from the Atoma. One can also see in the above photo that the low spots go down to the cutting edge and actually a slight 'dips' developed as I was working on the finish. Oh great.

Two low spots well visible - still showing the scratch pattern from the Atoma 140.
It meant that I needed to go all way down and redo all the finishing. I decided to go to Gesshin 400 for this job, but first I would put the knife under 90 degree to the stone surface (like I would want to cut the stone) - fix the blade profile so the dips would disappear (the knife lost some 0.5 mm of the blade height in the process). To make a low spot disappear one needs to grind all the remaining areas until the low spots are not low spots anymore and then keep grinding the whole bevel until the scratches from the low spots disappear. and then refinish the blade. And that is exactly what I did and it took me additional 2 hours of careful work.

Once I got the bevels fixed and finished up to Gesshin 4000 I decided to mount the handle and make the very last steps of finishing and sharpen the knife afterwards.

Knife ready for the handle to be mounted.
Just before I would start to glue the handle I would give it a coat of board butter, to minimize the impact of wiping some parts of it with Toluene later when cleaning it from the epoxy.

Since recently I have started to mount (glue) the handle in 2 steps. First I do the gluing itself - I mix the glue, heat it up with a hot air gun so it becomes less viscous and pour it inside the handle. Than I warm up the tang and slowly insert the tang - trying to allow the air to escape. After that I make sure I remove all the excess glue from the blade and the handle (I use paper towel and Toluene for that) and then I allow the glue to cure.

During curing (mostly because temperature related volume change) the epoxy would slightly contract and thus empty voids would appear next to the blade at the top of the ferule.

The next day I would therefore mix a different - somewhat faster curing (15 minutes working time) epoxy to fill the voids. I would again use the hot air gun to make sure the epoxy fills the voids nicely and that air bubbles do not remain trapped in the epoxy. And I would wait until the epoxy would start to get a little thicker as it starts to cure. At this stage I would use small pieces of paper towel wrapped around the wooden ice cream sticks dipped in Toluene and wipe the excess epoxy away. The reason for letting the glue get a little thicker is to avoid 'pulling' it out of the voids I am just trying to fill. Once the glue gets thicker this does not happen anymore.

Gluing the handle.

Allowing the glue to cure. Yes, I need
 a better solution to keep the blade upright.

Filling-in the voids.

Once the handle was mounted I would give it again a coat of board butter for the good measure and then finish the bevel on the Uchigumori stone and finally even out the result with Uchigumori fingerstones. And then the knife was finally finished.

Finished knife

(photos taken before final sharpening of the cutting edge)

Here a tiny gap can be seen between the ferrule and the spacer.

Lessons learned:

Lots of stuff :)
  • Be very careful when grinding close to the heel or to the tip - if you do (even only just partially) grinding movements that are perpendicular to the cutting edge (instead of sweepping movements under angle), than you have a good chance to grind in low spots. If these are shallow enough, you will not notice them until later when finishing the bevel on stones. You do not want that to happen.
  • Do not grind the bevel down to 'zero grind' (or 0 thickness at the edge). Once you will go to sharpening stones for finish you will need some more material to be removed before the scratches are gone PLUS since it is not really possible to keep perfectly the same angle and thus will start to loose material at the very edge what will create uneven profile (which you will have to correct what will cost you blade height and work) PLUS you will experiene pieces of the cutting edge chipping out (in particular on coarse stones) - these will get caught in the mud and cause deep scratches in the cladding generating further work.
  • IF you do get to the point that you discover low spots during bevel finishing (they will become visible latest on 400 grit stone) than you have 2 options:
    1. If you do not have dips in the cutting edge yet (at those low spots), than keep working the bevel, but avoid material removal at the low spots. Continue at the coarse stone until the rest of the blade will match the low spots.
    2. If you (like what happened to me above) already have 'dips' in the edge profile appearing, than take the knife at 90 degrees relative to the stone, grind the edge until the profile is restored (thus loosing some blade height) and then continue like in the point (1)
  • Do not hurry when finishing blade (or handle) as even small mistakes can set you back and you will be forced to re-do many steps and loose much more time.

Thursday, November 9, 2017

Project #19 - 210 mm Niolox gyuto for a local chef

There is a small Italian restaurant in Aalen called Buon Giorno. We have been their regular guests since they have opened a few years back and we must have eaten there well over 100 times. We love their food and became friends with the owners and it is a place I always look froward to when we head to town on Saturday to do some shopping on a local market.

Since I have started making knives I had this idea that one day I will make a knife for the chef. It took me a while to get to the point when I was able to make a decent looking knife with a western style handle, but I kept this idea and finally I have managed to make it happen.

One surprising fact about this project was that I did not produce any major screw-ups or mistakes, an exception to the rule :)

The design

I have watched the chef cooking, so I know that he uses about 21 cm German chef knife, so I have decided to make him a knife that would follow similar pattern to increase the chance that the knife will suit his cutting style.

The main design points were:
  • 21 cm blade with just a tad more belly towards the tip than I would normally do
  • Niolox stainless steel at 61 HRC
  • Western style, hidden tang handle (I have not made a full tang handle yet, so I stick with what I can do)
  • Handle materials: Buffalo horn, white G10 spacer, stabilized & dyed handle.
  • Some sort of blade protection for storage and transport - which became a simple leather sheath.

The blade

As usually it started with designing the blade, copying it on a piece of steel and cutting out with a hack saw.

The rough blank of the 210 Gyuto at the bottom of the photo
The blank was then brought to final profile with a belt sander, edges cleaned up to #220 grit. After that the edges were painted with a blue permanent marker and center lines were inscribed. Now the grinding could begin

After first few passes on a #40 belt
I usually start putting a relatively steep bevel on the blank (see the photo above) and leave the edge thickness at cca 1mm. The only practical reasons to that is, that having limited grinding experience and a bit wonky setup, little mistakes may happen in the next hour or two if grinding and having little more material on edge gives me a bit of a 'buffer' should my hand slip. Later during the pre-HT grinding the edge is brought to about 0.5mm thickness.

In further grinding steps I have pushed up the (at this stage slightly convex) bevel towards the spine and then started to grind the distal taper. I would go down to about 1mm thickness at the spine at the tip and around 2mm half way between the handle and the tip. Then it was time for a HT (done by J├╝rgen Schanz)

Blade right after HT.
After the HT I would first finish most of the grinding with the #40 belt. I usually leave the edge thickness at about 0.3 mm before moving to #60 and #120 belts. 

Setting the bevels with #1000 water stone

Once the rough grinding work was finished I would take the blade to my #1000 water stone (Watanabe AI#1000) to check for any low & high spots that I may have induced along the way. This stone is particularly suitable for this job as it not only cuts fast, it also does not wear much so after flattening it keeps flat without excessive flattening - something that is important to get the bevel setting done.

Note: This step with setting bevels with a water stone before I actually finish grinding with finer belts should not be necessary later down the road once I take my new 2x72" grinding into operation, as with the wider belt and more flexibility in setting up the grinder I should be able to get more even results. 

Scratch removal

Note: There are many ways to put an even finish on a blade. Different approaches have different pros and cons. At some point I may write an article on that topic, but I am far from having a decent grip on this topic at this point. With every knife I tend to try a slightly different approach and see what works best for me.

This is probably the least enjoyable part of the whole process, but it is necessary to be able to put any decent finish on the blade. Since the grinding was done with a #40 belt, one needs to go through some sort of progression of abrasives to get to at least #400 (or finer) finish. My progression with this knife was the following:
  • Most of the grinding is done with #40 belt - so that is the starting point
  • Finish the grind with #60 belt under slight angle to make sure all #40 scratches are removed. This IS important
  • Clean up with #120 belt - this time the scratch direction is as with #40 belt, so that I can make sure all #60 scratches are gone
  • Bester 220 stone - firstly to finish the grind and secondly to put a first more-less even finish on the blade
  • Watababe AI 1000 stone - full blade finish
  • Gesshin 4000 full blade finish, This one is NOT completely smooth as the stone is rather hard. I may skip this step in the future.
  • #600 sandpaper
  • #1000 sandpaper
  • #2000 sandpaper

Starting to grind with #60 belt after #40.

Also - normally before I would switch to the finer belts I would finish grinding the profile of the tip (as up to this point there was no point). But since here I have ground the blade up to #120 belt I had to watch for scratching of the side of the blade that will have contact with the work rest, so I would put some tape on it.

About to grind the profile of the tip

Putting some tape for protection on the right side of the blade.
In this case I did not final-shape the tang of the blade before HT (because I forgot), so I had to do that as well. It actually makes more sense to do that beforehand as it is much easier to shape the heal/choil area before HT as it can be done rather quickly with files and sandpaper.

Bevels cleaned up on the Bester 220
Whole blade finished on Bester 220.

Once I had the blade at #120 belt finish I moved to sharpening stones to finalize the grind (I still had some steel on edge at this stage) and to continue with refining the finish. I would start on the Bester 220, get the bevels even and edge thickness close to 0.1 mm and then work higher up the blade until the whole surface of the blade had a finish from #220 stone.


After the Bester I continued with the AI#1000 stone and removed all the scratches left by the Bester. The final stage was done with the Gesshin #4000 stone. The finish was very 'patchy', but the important part was that all the scratches from the 1000 stone were removed.

Finish after Gesshin #4000

I have yet to find a better tape than the orange Tess -
it hods well and does not leave any residue - even when
left on the blade for longer time (up 2-3 weeks)
Last step before switching to

Now I would switch to hand sanding. I always put a masking tape on the bottom side of the blade to protect it from scratching while the upper side is being sanded.

About to start sanding the left face of the blade

As usually I have used my very simple 'sanding station' - a blade-like shaped piece of a 3cm thick beech wood clamped to my workbench. Yes - there is a room for an improvement there.

I usually use WD40 as a lubricant for grits up to #240 (#400) and switch to Windex (less viscous than WD40) with finer papers. The advantage of the Windex is, that it keeps carbon steel blades from rusting. That is important as hand sanding take s long time.

Left face of the blade at #1000

With this particular blade the sanding of the left face went fine - I went through #600, #1200 and finally #2000 grit and the result was fine. But something wend wrong with the right side. Once I switched to #1200 paper I started to discover short (about 5-10 mm long) scratches parallel to the spine of the knife all over the blade.

Short scratches all over the blade ... oh well ...
I had no other choice that go all the way down to #400, remove all these little scratches (which proved to be quite deep) and then work my way back up to final grit.

Starting to remove the scratches with a #400 sandpaper ...
... and gone they are!

#2000 grit finish (semi mirror)

Note: I am yet to figure out how to put a finish on Niolox that I really like. Going for a mirror polish may be possible, but give how hard the steel is to abrade (it literally eats sandpaper) that would be a lot of work. At grits around #600 - #1000 one gets a mixture of scratches and reflecting surface that does not look too nice. What I am trying to achieve is a fine semi-matt finish, but I will need to experiment more to get there.

The only thing left to do on the blade was to etch the logo.

Stencil taped in place for the etching.

At this stage the blade was finished. I did work on the handle in parallel, but decided to separate this two parts here for simplicity.

The handle

The decision to go with a western style handle was based on the fact, that the chef has not used a Japanese style so I decided to make a handle that will in handling be closer to what he is used to.

I wanted to make the whole knife relatively lightweight and so to keep the balance point on around the pinch grip, I had to be careful with choice of materials and avoid heavy/dense woods or metals. The choice fell on a stabilized maple burl from Stabwood Lab. I do not know what kind of stabilization process they use, but the resulting wood is not as dense/heavy as from other makers and also feels more natural to touch. On the other hand, there seems to be a bigger chance for small voids and I also assume that the strength of the wood is not going to be quite as high as of the denser. But until today I did not have their product to fail on me so I plan to keep using it.

I need a band saw :)

Flattening & squaring up.
I wanted the handle to be a bit eye catching, so I have decided to use a blue-red dyed maple burl. Since the block was large I used only one half of it. Once the block was cut I flattened and squared up all sides by hand with #80 and #180 sandpaper.

Drilling the handle block.

Drilling the ferrule.

The handle block, the horn ferrule and the spacer were all drilled to accommodate a 12mm (diameter) dowel. Since this is a western style handle the ferrule was not drill through completely, so that the dowel would not show from the front. I call this a 'hidden dowel design'. 

Important: Since the drilling of the block is rather deep - even a small deviation from the intended direction could lead to problems later - I always check (with a straight longer piece of the dowel stock material) whether the drilled hole aligns. with what was planned. If not, than now is the time to make adjustments - either re-square the block, or just re-draw the center-lines so that later the dowel will be aligned with the handle.

Filing the tang opening.

The ferrule would be first drilled-through with a 3mm drill and then the 12mm drill would be used to drill through most of the length, leaving about 5mm of of material in the front. After that 2 more 3mm holes would be drilled in the front face and using a set of needle files a rectangular opening for the tang was made.

Testing the fit of the blade & handle components before gluing.

The dowel was made from a 12mm thick bar of beech wood. First a narrow slot was cut with a hand saw and this was later sanded with a #120 belt until the blade tang would fit. The fit was tested with all handle components before the gluing. Here some fiddling may be necessary to make sure, that there will be no gap between the bolster and the rest of the handle.

Gluing the whole handle.

To make sure the dowel will remain 'opened' first it was glued inside the handle block with a 5 minute epoxy. After that the spacer and the ferrule would be glued (G/flex epoxy) with the rest of the handle and allowed to cure for 24 hours.

Clearing the tang opening with a needle rasp.

It is advisable to use only as little glue as necessary, because otherwise it will leak inside the dowel-slot. Even though I was careful, I did need to do some minor filing/rasping after gluing to make sure the blade can be inserted inside the handle again. Here needle rasp is the best tool for the job. To make sure it will fit inside the narrow tang slot, it was flat-sanded on one side.

Cleaning & squaring up the handle block after gluing.

The handle block was quickly sanded to remove excess glue and to flatten the sides (the horn was a bit wider than the block). 

Now the handle design could be transferred onto the block. Care needs to be taken to get the alignment right. In some places there will not be much material left between the dowel and the surface of the handle.

Grinding the handle profile from the side ...

... and from the top/bottom

In subsequent steps a #40 belt would be used to roughly grind the profile of the handle - first from the side and the from the top. It helps to inscribe some guide-lines (symmetric relative to the axis of the handle) to make it easier to grind symmetrically from the left and the right side.

Coarse shaping the handle with #40 belt

Than the coarse shaping would start. I remove most of the material with #40 belt. Here one really needs to be careful, as the belt is very aggressive and it is easy to create dents with the edge of the belt. Once I had the approximate shape of the handle (though it would still feel too large in hand) I would switch to #80 or #120 belt to get closer to the final shape.

Filling the voids with glue.

Detail of the gluing.

I have mentioned voids in the wood - this particular block had one. So before I would move to hand sanding, I have decided to fill it with glue. For some reason I did not want to use epoxy and decided to give the 'Titebond Instant Bond' a try. This is basically a CA glue for wood. It turned out that while it works great on finer cracks, filling a larger void did not work so great (in retrospective - not a surprise) and I had to repeat the process several times. Eventually I managed to get the voids filled.

Finishing the surface with steel wool.

The handle was subsequently sanded with #180, #320, #600 and #1000 sandpaper. I have used either a rectangular piece of wood (in particular when sending over the spacer area) and piece of a round wood stock that I use for dowels, to finish the sanding (final shape little details, even out the surfaces, etc). Final sanding was done with #0000 steel wool.

Finished handle before Tung oil was applied.

Even though this handle is made of horn and a stabilized wood, I have used a few very thin layers of Tung oil (wiping away / polishing with a paper towel immediately after application) to seal a bit the not-so-dense handle bar.

The sheath

Since I did not know whether exactly the knife will be used I have decided that it should come with some kind of protection for the transport or storage. I have not made a saya or sheath before. I considered making a saya, but found out too late that the wood pieces I had for the purpose were too small. So I finally wend with a leather.

Since I had zero experience with working with leather I have decided to go with a very simple construction - two pieces with a spacer along the spine. I have used about 2.5mm thick, half tanned leather that was very stiff. The stiffness make it suitable for the job as the final sheath would be very strong, it was also a pain to cut and punch holes.

I have marked the profile of the blade on an A4 piece of leather and added ca 12mm for the seams. Then I have cut a piece of leather in with the same profile as the spine of the knife for the spacer.

Thinning the spacer
Since the blade has a pronounced distal taper I have decided to taper the spacer as well, so that the sheath would sit well when the knife was fully inserted. I first tried to use the curved beveler tool, but I was not very successful with it, so I used my belt grinder with #120 belt instead and in a few minutes I had a perfect distal taper on the spacer.

Gluing the spacer.
In the next step I have glued the spacer to one side of the sheath.

You can never have too many clamps in your shop.

Once the glue cured I have glued the tho halves of the sheath together.

Since it turned out that one can use the belt & disc grinder to work with leather I have used it to clean up all edges.

Punching holes made easy :)
After marking the position of the future seam with a groover I took the standard puncher and ... even with all the force I was able to produce I did not manage to punch a usable hole through the thick and hard leather. OK, a different approach was needed. Luckily, it did not take me long to realize, than I already have the optimal tool for the job - the drill press. I took a wooden board (some 20 mm thick) to have a smooth clean surface, drilled a small (about 3-4 mm) hole into it, so the needle would have enough space after going through the leather - and started punching. I still had a problem with the needle getting stuck in the leather, but once I got the idea to turn the drill press on - even this problem disappeared.

All holes punched (and re-punched from the other side)

I hurried a bit too much what resulted in holes not being quite as perfectly aligned as one could wish, but I got this part of the job done. 

Note: I must have made several things suboptimally, as for example - the groove I did for the stitch disappeared nearly completely during hole punching.

Yep, there is room for improvement.

The punched holes seemed to have fit the sewing needle and the thread quite well, so even though it was not a fast job to do, it went rather fine. Once I was done with stitching I have used a small amount of the wood CD glue to secure the seams.

Applying dark brown leather dye (in 2 separate steps) did help to make the imperfect stitching to stand out less. Even though not a work of art, I am happy to say that the sheath fits the knife very well. I will try to make it more elegant next time :)


The handle, the blade and the sheath.

At this stage the main work left to do was the glue the handle on the tang of the knife. This was the first time I did it in 2 stages. This was also the first time I have used a heat gut (from Proxxon as I wanted a smaller one with not as much power) to make the glue less viscous and thus easy to pour inside the tang slot - that worked great.

So the first day I glued the tang inside the blade, and only made sure that I wipe all the excess glue with acetone. This would leave the narrow gaps between the handle and the tang not filled completely.

Filling the gaps with epoxy.

So the next day I would mix a faster curing (15 minutes) epoxy, heat it up, fill in the gaps and wait until the glue starts to get sticky. The reason for waiting at this stage is to avoid the glue being 'pulled out' of the gaps while wiping out the excess and cleaning the handle and the ferrule.

Once the knife was all done the last step was to give it its first sharpening. Since the edge had basically zero thickness after all the sanding, it was a very quick job done with Gesshin #2000 and #4000 stones.

Finished knife

I took me well more than 20 hours of work spread over several months to finish this project. It was a very rewarding moment to gift it to the chef at Buon Giorno, who did not expect anything of this kind. 

The position of the center of mass is about 1 cm in front of the heel - pretty much exactly where I wanted it to be. The knife weights 160g without the sheath.  Thickness of the blade 10 mm from the edge it about 1.2 at the heel and tapers to ca 1.0 mm close to the tip.

So - this is how it looks finished:

Lessons learned

  • Always change directions when removing scratches. It can save you hours of work. I needed about 2 hours of hand sanding to get the right face of the blade to #2000, but for the left side (because I had to go back to #400 grit) I needed nearly 5 hours.
  • Hot air gun is a great help to get glue to flow into tight places
  • Before starting a brand new thing (sheath making in my case), do some reading and watch few YouTube videos to avoid unnecessarily suboptimal results
  • Drill press is a great tool to punch hole is hard/thick leather