Saturday, January 13, 2018

Project #25 - 150 mm tall petty from 1.2442

This was one of the fastest projects I have finished till today. A friend of mine who got a Moritaka AS 150 mm petty just a few months ago managed to bend it at work (while cutting !) and was in a need of a stronger & stiffer petty.

Since we have some experiments with 1.2442 steel in mind for the near future, I offered him that I could make him a petty from this steel as I have not used it yet (though I bought it about a year ago).

From the design point of view the idea was simple - ca 35 mm tall, 150 mm on edge, WA handle.

The blade

As usually, I have started with the blade design. Here I have decided to use the profile (of the cutting edge only) of a Yoshikane SLD 150 petty, which has proven to be very practical. I have then adjusted the height as the Yoshi is only about 30 mm tall. 

This was the first time I have worked with the 1.2442 steel (not in production since quite a while), which bears some similarities (composition wise) with Japanese blue #1 steel. When cutting the steel with a hack saw one would notice that there are alloying elements present, but it was still easier to work with than for example Niolox, though not as easy as O1.

All of the pre-HT steps were 'standard' ones, so here just shortly:
  • cut out the blank from 2.7 mm thick stock with a hack saw (yes, I leave the tip flat until after HT)
  • finish the profile with a #40 belt
  • clean up to #220 belt
  • paint the edges blue with a permanent marker
  • scribe the center line on both edge and spine (including tang)
  • grind the bevels and distal taper - I went down to about 1 mm on edge to minimize the risk of warping during the HT - I have not worked with this steel before.
  • Finish the profile of the heel (much harder to do after HT)
  • Sent the blade off to HT to Achim Wirtz to be hardened to HRC63

Blade after HT.

After HT I would first thin the the grind down to last 10% (leaving about 0.3 mm edge thickness) with the #40 belt.

Grinding after HT with #40 belt
Distal taper - the tang will be worked on a little later.

Close to final geometry

At this stage I would go briefly to 300 water stone from JNS to check and clean up the bevel grind to make sure that there are no defects like over-grinds and low spots. I was not trying to get the final bevel grind - really just checking the consistency. It all looked pretty good, just at usually the heel was a little thinner last 2-3 millimetres.  I was not trying to get 'perfect' bevels at this stage or even shinogi line.

After that I would proceed with shaping the tip and tang of the blade.

Shaping the profile of the tip (after working the bevel on 300 stone)

Once all the coarse grinding was done (blade geometry, tip shape, tang shape) the next step was scratch removal. During this step I would not worry too much about that bevel I did on stones as I was not trying to get as little as possible material removed. I would proceed with #60 and #120 ceramic belts and then proceeded to 3M Trizact 'gator' A100 belt. The A100 would be around #200 grit and frankly I would have been preferable to have the coarser A160, but it appears not available in 1x30" size. 

Grinding with #60 belt under different angle to remove all #40 scratches.
After the A100 I went  to A65 - always slightly changing directions. At this point I realized, that I forgot to round the choil and spine (ideal point to do that would have been after #120 belt), so I first coarsely rounded the spine with a belt and finished to #1000 grit by hand. The choil was rounded entirely by hand and then also polished to #1000. Once these parts were done I continued with #65 and #45 Trizact belts.

Rounding the choil with #240 grit. The light accentuated the scratches,
they were far less scary :)

At this stage of finish I would normally switch to hand sanding going to whatever grit would look nice (I am normally by semi-matte finish). But I was under a time pressure as I wanted to present the knife to my friend (who did not expect to see it anytime soon). So I took a shortcut. I decided to make  an experimental finish. I had a second session on the stones - this time a progression of 300, 1000 and 4000 and ground the bevel down to is final edge thickness (not more than 0.1 mm before sharpening).

I followed by finishing the blade with A30 belt making sure all scratches are gone. I tried to avoid the bevel as I did not intend to remove any larger amount of material there, just final finishing before sharpening once the knife was completed.

In the process of last scratch removal with A30 belt.

The last step on the belt grinder was made with a fine (blue) Scotchbrite belt. There I just wanted to get the finish a little smoother (the belt is nearly too sharp for that). I knowingly also toughed the the bevels so that I had an even finish on the 'shinogi' line.

Finish after fine Scotchbrite belt. Again - the direct light makes the scratches
to stand out more than they would appear under softer light.
The same Scotchbrite belt finish under different angle

The blade would not be finished without a logo ;) On this blade I only did deep etching with DC without using AC afterward to blacken the logo - as was wished by my friend. I have to admit I like this less obtrusive and will probably stick to it with most of my future knives.

About to etch the logo.
As always until now I have used the Electrolyte 94 as electrolyte, 12V setting on the etcher and etched for 6x3 seconds (e.i. lifting the etching head every 3 seconds so that the gas that is produced in the process can escape and does not cause uneven etching

The handle

While waiting for the blade to come back from the HT, I would start to work on the handle. The design was again a 'standard' one using buffalo horn for the ferrule and stabilized & dyed Australian wood (curly spalted Boxelder) with a beech dowel inside. Since this handle was a rather subtle one, I decided that apart from cutting the ferrule and handle block to rough shape with a band saw, I will do all the shaping & sanding by hand on a stone sanding block.

Handle materials

The basic process of the handle making:
  • cut the & square up a piece of buffalo horn and handle block
  • drill the ferrule and handle block
  • check that the handle block axis (defined by the drilled hole)aligns with the ferrule & glue them (using my own gluing press that allows using a piece of dowel material for initial alignment)
  • Once the glue cured clean & square up the future handle

Handle components cuts and squared-up

Gluing the handle using a jig. The dowel is
removed once the handle is clamped down.

Normally I would glue in the devel before I would glue the handle parts together, but this time it took longer to get the blade back from the HT and I did not want to loose too much time, so I glued-in the dowel at a later stage (when the blade was back and I could test the fit).

Handle squared-up after gluing and ready for shaping

Normally I do the rough shaping (= final height and width including distal taper) with a coarse belt, but I decided to do this completely by hand. I would do this on a #80 grind sandpaper taped flat on a stone (old table-top)

Handle after coarse shaping
Once the desired height and width (with about 1 mm in every direction left for further sanding) was achieved, I continued through 180, 320 and 600 grits.

Coarse shaped handle refined to about #600 grit.

In the next step I have sanded the handle to octagonal shape. Again - this is something I usually do with the little disc sander that is part of my belt sander, but I simply wanted to do it by hand. This is an interesting experience and allows to get the feel of how important is even pressure distribution.

Once the handle was shaped and finished to #600 grit the blade finally arrived from the HT and so I could make the fitting dowel for it.

Handle shaped and finished up to about #600

I have to admit that since I got the little Record Power BS250 band saw, the cutting of dowels got so much easier. Once the slit was cut it gets widened on a belt sander (#80 or #120 belt seems to work the best) until I get a nice, easy with with the tang and the handle

Dowel cut, now the slit will be widened with a belt sander.
As you may see in the photo below - I tend to make the dowel some 5 mm longer that the drilled opening in the handle - the reason is, that the front side of the dowel might have suffered uneven grinding with the belt sander, or it might get sanded by a rasp after gluing. So I rather make it a little longer and then sand to length after gluing.

Checking the fir.

Once the dowel fits nicely I glue it inside the handle with epoxy. I tend to create small 'pockets' (dips) on the side of the dowel with a round file so that if there is a bit too much epoxy it can go there instead inside the slit itself. You really only want to use just a little epoxy at this stage, because if too much of it leaks inside the handle you will spend a lot of time with needle files and rasps trying to get it out.

As always I use a piece of scrap steel shaped like a very thin edge to push the dowel open while the glue cures, so there will be no gaps between the dowel and the ferrule.

Gluing the dowel

Once the handle was finished this far I tested a little more to see how it feels in hand (with the blade inserted) and got the impression that while I like the overall size and shape, it would feel more nimble if it were a little narrower in the front. I have have covered most of the handle with tape (remember, it was already sanded to #600) and used #180 sandpaper to give a bit of horizontal distal taper to the ferrule.

About to start sanding the distal taper.
Thanks to the fact that the handle already had a #600 finish, it was very easy to observe where the material was being removed. I started by tilting the end of the handle upwards very slightly and applying pressure only on the very front of the handle. I would stop after every few passes and check the progress. Once I have established a new bevel I would continue until it reached the end of the ferrule. I would constantly check and if necessary compensate any unwanted tilts.

After first few passes - looking good so far.

The horizontal distal taper sanded in.

Once the taper was sanded the whole handle was finished up to #1000 grit and the front and rear edges were chamfered. I also used steel wool when finishing the handle, but it was not a particularly good idea with this wood which has a somewhat coarse and not homogeneous structure and the steel wool would tear little pieces out. 

Front side of the handle sanded to #1000 and the opening lightly filed
so that the shoulders of the blade would fit nicely.

Because of the slight tear-out I have the handle once coat of Birchwood Sealer & Filler, sanded it lightly afterward and followed with 2 or 3 coats of Tru-Oil for a good measure. As always, I would apply the Tru-Oil and while & polish the handle with a paper towel immediately after the application.

Tru-Oil curing after application.

At this stage both the handle and the blade were finished (the blade will still get slight refinishing of the bevels on stones) and thus ready for gluing.

Well, let's do the last step.
As with the last few handles I would heat up the G/flex epoxy to make it easier to get it inside the narrow tang slot, then heat up the tang of the blade and insert it carefully. Once the epoxy started to come out I wold let the blade to sink in the handle slowly while wiping the excess epoxy. Since I use G/flex which has 45 minutes pot time I did not have to hurry and even had time to take some photos :) Once the blade was in place I would heat the top of handle gently with the hot air gun to allow most of the bubbles to escape.

I have used small pieces of paper towel wound round ice stick and dipped in Toluene to clean up the blade and ferrule from epoxy rests.

The handle is in place, the last bit of epoxy is still to be cleaned off.
Gluing the handle this way also means, than more often then not the epoxy will shrink a little while cooling down (some air bubbles always remain trapped inside) and thus a shallow void between the dowel and the blade would appear. This is is filled with epoxy (Blade Bond Ultra that has pot time 15 minutes) the next day in a similar manner - the mixed epoxy is heated up and just very little of it is applied to the contact area between the blade and the dowel. Heating the applied epoxy with the hot air gut would allow it to fill the narrow void and the bubbles to escape. This time however I would wait until the glue starts to set it (get thicker) and only then I would use clean the rests off (paper towel, ice stick and Toluene). If I were to do it too soon, I would risk 'sucking' out the epoxy from the freshly filled void. The reason to use different epoxy is that I do not want to wait for an hour for the epoxy to start to set it :)

Gap filled with the epoxy, the excess was already removed.
After last clean-up of the bevels on the stones the knife was officially finished.

Finished knife

Lessons learned

Not so much went (thankfully) wrong this time
  • 1.2442 steel was nice to work with (in comparison to Niolox every steel feels nice to work with though) 
  • The "narrow wide bevel" grind appears to work very well (feedback from my friend)
  • The gentle horizontal distal taper improved the feel in hand considerably
  • I am very happy how the belt finish turned out, but I have a lot of room for improvement (the finish and the efficiency) there. I will need to experiment with different belts to get the most out of it. I plan to make this simpler but very functional finish in the future more often (not only on Niolox)
  • I may be doing more knives like this one in the future. In general I will probably start to make small batches of knives once I get a knife that I (and in particular my test users) like.
  • Again - I was in a hurry to finish this knife and so I did not make proper photos or a video. I need to improve on that.

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.