Wednesday, June 15, 2016

Project #3 - Petit Gyuto Kitchen Knife

Tip: I have summarized what I have learned from this project in the "Lessons learned" Paragraph close the end of the article.

The Blade

With the relative success of grinding I decided to give a kitchen knife a try. I decided to go with a sort of 'tall petty' with size of about 170 mm and height 37 mm. Steel was O1 with thickness 2.2 mm. The design was a 'free hand' with curved rulers.

The design and steel with traced profile

Once the blank was cut out with a hack saw I have used first coarse and than a fine knife to finish the profile. I have left the blade wider at the tang area to have more mechanical stability while working o the bevels. Before I proceeded to grinding I have scribed a center line on the spine and the cutting edge so that I could keep the grind symmetrical.

This was my first try with grinding at angles this low and I was rally guessing and adjusting the grinding angle several times. Still - it turned out later that I have left the blade thicker that I should have.

Grinding the first bevel.

Once the bevels were ground I have used the cross-draw technique (see the article on Bevel grinding jig by Aaron Gough") to smoothen out the profile and to create some distal taper towards the tip. The the blade was set for HT to Achim Wirtz.

Blade after HT.

Choil shot after HT.

Once the knife came back from HT I realized that there was too much material left - meaning the blade was too thick to perform as I intended. For example - the thickness of the blade 10 mm from the cutting edge was 'whooping' 1.7 mm, but I was aiming for 1.1 - 1.2 mm. That meant the blade needed thinning of about 0.5 mm over most of the blade surface area. That may sound like a lot, but with a HRC 60 - 61 steel and no powered tool that meant hours of grinding even with the most aggressive material - a diamond plate. Indeed - I bought the Atoma 140 solely for this purpose. I have also got a digital calliper to be able to check the blade profile.

Mid-work - the blade, the Atoma plate and digital calliper

While working on the Atoma I would grind the blade at given distance from the edge and after about 100 strokes move some 1-2 cm towards the tip. This was good to reach certain consistency, but it left long traces on the blade and also the blade geometry (the grind) was not smooth, but had clear 'shoulders'. Since the blade would be wet for prolonged times it would start to rust (this rust was of course removed in subsequent steps)

The blade after the basic thinning was done

To even out the bevels I would use the following technique - I would place the blade perpendicular to the stone (so that the scratches on the blade would be perpendicular to the edge) and while grinding the blade I would slightly 'rock' the blade. This way I would not be grinding at single place, but rather move from edge to spine and back with every stroke. This allowed me to smoothen out the bevels and also get finer scratch pattern.

Part of the blade smoothen out on the Atoma with the 'rocking' technique.

From here on the task was to remove the scratches and get smoother finish. The next step was done with Bester 220 stone (aka 'the pink brick') - a large, coarse and soft stone that is ideally suited for such a task. I would use the same 'rocking' technique, but the knife was held under ca 45. deg angle so that I could see whether I have removed all the Atoma scratches. This was somewhat harder to accomplish, so the resulting finish was not quite as smooth. That was not quite as relevant, as subsequent steps would remove that.

At this stage the grind of the blade was finished.

Starting to work on the Bester 220 stone.

After finishing the blade with Bester 220.

Close-up of the finish with Bester 220.

Finishing the blade - part I

Tip (from Greg from Wabocho): Before going for a final finish you may want to quickly put an edge on the knife, use to cut it some food, to get an idea whether it performs as you wanted. If it does not - go back and work on the grind (with an Atoma in our case).

Next step was to move to wet sanding paper. I have used WD-40 as wetting agent. It turned out that the best grit to remove the scratches from the Bester in reasonable time was 120. I tried it with 180, but that seemed to take too long. Once I was done with 120 grit I moved to 180. Again - I tried to go directly to 240, but that was too slow.

To sand the blade I have cut the sanding paper in 3 long stripes, rolled one of them tightly on a piece of wood and just put some WD-40 on the section that was just going to be used. Once the sanding paper would get clogged I would move to another section (and tearing away the used one)

I have used just a 10x30x250 mm hard wood bar as my sanding tool. I will be making some DIY sanding tools/holders. There are some good ideas out there (e.g. what Nick Wheeler uses), I just need to give it a little thought and find something that will work for me. So for now it is just this simple piece of wood.

My sanding tools.

Blade finished and secured with tape and waiting for the handle.

I finished first side to 180 grit, than swapped the sides. At that point I realized 2 things. First - during the thinning I got too close to the edge towards the tip and altered the profile - something that needed fixing. Second, once I have flipped the blade over to the other side I found out that the loose grit grains from the paper (which created mud with the WD-40) got under the blade and between the blade and wooden holder and cause scratches.
Rough finish with #180 sanding paper

Before fixing the finish I have decided to take the blade back to stones to fix the profile close to the tip. I have used JNS 300 stone - it is very fast and hard stone (dishes very little) and thus allows for precision. Once this was done it was back to sanding paper.

Finishing the blade - part II

With the lesson learned about scratching the side of the blade that was facing the wooden support I have used Tesa plastering tape (strong orange, 50mm wide) that while holds reasonably well, does not leave residue once removed.

Using Tesa plastering tape to cover one side of the blade before sanding the other side.

About to start to sand the blade after the profile was adjusted on the JNS300 stone.

For the finishing I have turned to Rhynowet Redline sandpaper and used WD-40 as lubricant. I started with 180 grit under ca. 45° relative to the edge so that I could make sure that I remove all previous scratches (which were mostly parallel to the edge). Once I got the result I wanted I moved to 240 grit, changed the angle so that the new scratches would be perpendicular to the previous one and again kept sanding until the previous scratches were all gone. This was repeated with 320 and 400 grits with the little change, than with 400 grit I sanded the blade parallel to the spine.

Sanding with #180 paper at ca. 45° relative to the edge/spine. I am just starting here - you can still see the parallel scratches from the finish prior to thinning.
To put final finish on the blade (i.e. remove the light swirls that are created when you change the direction during the back-and-forth movements I only used long strokes from the handle towards the tip without stopping or changing the direction. I only started this finial finish once the blade had only 400 grit scratches on it.

Once one side was finished I did the same on the other side (and of course taping the just finished side with the Tesa). I needed around 1 hour per side.

Blade finished to #400 grit.
Blade finished to #400 grit.

Blade finished to #400 grit. Yep, the tip took a little damage.
Part of the sanding paper and towels I used to finish the blade.

Blade finishing - mistakes

I have made 3 smaller mistakes in the process.:

First mistake: The above mentioned scratches on the opposite sides caused by the steel/grit/WD40 mud getting under the blade. Solution - use some tape to protect the side of the blade which is facing the support.

Second mistake: I have used kitchen paper towels to wipe the blade (so that I can check the status). When I was already at 400 grit I wiped the blade with already used towel and as I wiped the blade perpendicular to the sanding direction, I actually managed to induce fine scratches. Solution was using clean towel and wipe in the same direction as the blade was being sanded. 

Fine scratches left by the dirty paper towel.
Third mistake: When doing the final finishing strokes I did not only start the stroke with the edge of the wooden pad (which I used as a support for the sanding paper), but with its full width (30 mm in this case) - and since I always started at the same place (the clamp was a natural stop) - this left me with a 'line' 30mm down from the clamp with light swirls. Solution was to slightly tilt the pad and start the stroke with only its edge.

The faint 'line' some 5 mm from the heel across the blade left where the front edge of the sanding bar was located during the long strokes.

The Handle

Since this is a japanese-style knife I also wanted to make a matching handle for it - a so called WA handle (these are most often octagonal, oval or D-shaped). Traditional WA handle have water buffalo horn ferule (mostly black) and ho-wood (magnolia) handle. Second most common material is burned chestnut. These handle are made in a particular way which I can not replicate in my shop. However many western knifemakers make WA handles and have shared information that I found very helpful.

After long consideration I decided to use a piece stabilized Oregon Maple for the ferrule and Carelian Birch for the body of the handle. The Maple was a left-over from some custom  handle. The Birch offered a nice contrast and was also relatively cheap - I did not want to invest too much in my very first handle as a lot could go wrong (and partially it also did)

Construction (two of them)

Once the materials were picked the question was - how should the handle be constructed. I did not want jut to glue the two material together as the joint could break while working on the handle. There are different ways to approach this, I have tried 2 here.

Approach #1

I decided to use a thin (1 mm) plate of nickel silver as a spacer. Then drill two holes 10 mm (symmetric to the center) apart with 2 mm diameter and one hole in the center of the spacer. Than drill the center holes in both the handle and the ferrule materials and finally use the spacer as a mask and drill ca 10 mm deep holes in the bolster and handle. Once that was done I would cut two, 2 mm thick pieces of round nickel silver and use them as hidden pins for more strength. Se photos below for better explanation.

Materials for the first approach. The spaced already has the center hole and 2 pin holes drilled.

Drilling the center hole in the handle block.

once the center hole was drilled I used the pin to secure the spacer in place and used it as a drilling mask.

Drilling the hole for the second pin.

Repeating the same procedure with the ferrule block.

Parts ready for further processing.

Opening for the tang in the spacer (making sure it is large enough.

Once the guide holes were drilled I would use 3mm drill bit and drill 3 holes in the body of the handle and use the drill and files to create an opening for the blade tang. This part proved a rather hard to do as the drill bit was thin and would bend easily. Finally - I managed to break the 2 mm drill bit when drilling the ferrule.

While this is definitely an approach that works, I was not happy how it was developing and decided to try something else.

Approach #2

The second attempt was to use a slotted dowel that would connect the ferrule and the bolster and this allow for stronger bond. Since the dowel has a diameter of 12 mm I have used 12 mm drill to make holes in the body of the handle and the ferule. The hole in the handle was made deep enough so that there would be enough depth of the knife tang. The ferrule was drilled up to last 3-4 mm from the front face. I have used the previously drilled 2mm hole as a guide, so that later the opening in the front face of the ferrule would be on axis with the dowel.

Note: There is an excellent thread on KKF from an experienced handle maker on this style of handles - check it out here.

Drilling the dowel hole over the already done tang slot.
The slot in the dowel was cut with wood saw, which leaves wider slit than a hack saw. This would then allow me to use the belt grinder and widen the slit further until it could accommodate the tang.

Widening the slit in the dowel with the belt sander.

3 basic parts ready for gluing.


Once all parts were finished I drew lines on the body of the handle to mark the center of the handle. Since these could get lost in the further processing, I also used a hole punch to make a small dent in the bottom of the handle to mark the position of the axis more permanently.

Before I would proceed with gluing, I would dry-test the parts. I have sanded the bottom most part of the dowel a little for easier fit. Than fitting the dowel inside the body of the handle, inserting the knife blade and checking together with the ferrule, that the dowel will sit deep enough for the tang. I would also check that the length of the dowel and the opening in the ferrule match.

The gluing was a 2 step process. First I would use a 5 minute epoxy to glue the dowel in the body of the handle and let cure for about 30 minutes. At that point the dowel could not be moved accidentally. I have also prepared the two fibre spacers and check the fit together with the ferrule. Once everything would fir I have glued the whole handle.

Important note: Use just enough epoxy, otherwise it will leak inside the handle (dowel slot) and give you a headache once you want to mount the handle on a tang.

Handle curing after final glue-up.

Rough shaping

Once the glue was cured I proceeded with sanding it to its shape. I have marked the width and height of the handle relative to center lines and first sanded the wider sides with a #60 belt. This took just a few minutes.

Handle ready for shaping.

Once the two sides were sanded I quickly flattened them on the disc grinder. Than I marked the width of the handle and repeated the step above.

Wide sides of the handle sanded and marked for the second step.
Again, I would flatten the freshly sanded sides on the disc grinder. Now the final shaping may start. At this stage the handle is a 20 x 25 x 150 mm block with no distal taper). Since the final size will be a little less (this is a handle for medium sized knife), this is the time to check whether the handle is centered. I have managed to get some left-right asymmetry so I would first correct this before proceeding.

Handle ready for final shaping.
There was one more thing to be done - the opening for the tang in the ferule. This could have been done at an earlier stage - either directly after gluing, or even before the ferrule was glued on the handle. But since I did not realize it than, I had to do it now.

First I would drill 2 more holes and then use a thin round file to connect them.

Drilling 2 more holes in the front face of the ferrule.
Once I could it a small flat file inside the opening I would keep filing until the opening was large enough for the blade. I actually made it larger as the blade is only 2.2 mm thick and my files are little thicker. But that is not a problem since the remaining space will be filled with epoxy later.

filing the opening for the tang.
When I tried to fit in the tang I realized that some of the epoxy leaked inside the handle, so I had to remove it with a file. Not a huge problem, but something to think of for the future.

Testing the fit with the blade.
Final shaping

The task was to give the handle a slight distal taper and grind the edges to get octagonal cross section. This proved to be a little delicate and not very precise.

I have first worked the distal taper. I would allow the whole side to have contact with the sanding surface, but would only apply pressure close to the ferrule. This meant that there would be more material removed and one end, and much less at the other. From here on I would often take the handle in my hand to see how it feels size-wise.

Once the size of the handle was more-less right (OK it felt still a little large as the edges were still there) I would try to grind the octagonal shape. Since I did not have any tools or holder to keep fixed angle I had to do this 'free hand' - only using the work rest as a guide. This of course resulted in not too even grinding lines and angles and needed to be done with care. I was touching-up the same place several times. For the future I  plan to make a holder that will allow me to keep a fixed angle.

The handle after final shaping.
Surface finish

Once the shape was where I found it acceptable I cut the handle to its final length (keep in mind the length of the dowel - you do not want to see it again and then hand sanded all side on #240 and #400 sand paper. 

I have used #240 sandpaper to 'bevel' the bottom edges of the handle and used the #400 sand paper to slightly round the edges on the ferrule. Quick polish with steel wool and the handle was done with sanding. It would have been beneficial to use #600 and #1200 sand paper before the wool steel, but the result was still very nicely feeling. The wool steel brought nice depth to the ferrule.

I have planned to use either a Tru-oil or a Tung oil, but once I have tested both on the little piece that was left after the handle was shortened, I have decided to go with just a board butter (mix of mineral oil and bee's wax), because I did not want the birch to darken too much. I have applied a thick layer of board butter and allowed the handle to soak over the night.

Applying first layer of board butter.

I was surprised to see that the oiling did not raise the grain of the handle. I only sanded it slightly with a micro-mesh pad (grit #2500 I think) and applied another coat. Since the handle did not get a pure oil soak I expect it will need several coats with board butter within next few weeks before the surface more-less saturates.

Gluing the handle

I have decided to use common 90 minutes UHU Epoxy. There are special epoxy glues on the market for knifemaking, but WA handles do not need to be attached with quite as much strength as scales to a full tang handle. In fact - traditional handles WA handles are only friction-fit to the tang (usually burnt-in).

Tip: It takes quite a while to get enough glue inside the handle - do NOT use 5 or 10 minute epoxy.

Let's bring these two together.
Advantage in a different glue would be lower viscosity that would make it easier to get the glue inside the handle through that tiny opening in the ferrule.

Before I would start I have covered the ferrule with a painter's tape. The tape selection is not so crucial here as the handle was oiled so that the risk that the tape would leave some residual on the handle is low. In fact - I had hard time to actually make the tape stick to the handle.

Covering the ferrule with a tape.

I have mixed the glue and since it has relatively high viscosity, so I have used a hair dryer to heat the glue up to make it a little less viscous. I have gently clamped the handle in a vise and tilted it slightly, so that the air could get out of the tang opening more easily while I was trying to get as much glue inside the handle as possible.

The best way to get the glue inside was to use the tang to push the glue deeper inside. I continued adding the glue until it would start to come out when the tang was pushed close to the final depth.

Slowly feeding the glue inside the handle.

Once I was happy with the amount of glue, I have removed the tape from the ferrule and kept wiping the glue excess until there was no more coming out and the ferule was clean. I also kept wiping the exposed part of the blade.

Once the gluing looked fine I have left the knife in the vise with blade pointing upwards until the next day.

Now make sure that there will be no glue left on the ferrule or the blade.

Once the glue hardened the knife was finished and the last step in the process was to sharpen it. Since the blade saw a lot of work (thinning) with the Atoma and hand sanding - the edge had effectively 0 thickness. Also a tiny bit of the tip got 'lost' in the process, so this also needed to be fixed during sharpening.

Once the handle was glued on the knife I have realized that it is a little on the large side for this knife size, but I did not want to risk damaging the whole knife with handle re-shaping on the disc grinder.

I have used JNS300 and Gesshin Synthetic Natural stones to put a shaving sharp edge on the knife. I would normally used 3 stones as the difference in grit between the two is large, but my medium stone (Gesshin 2000) was on loan so I had to manage without it.

About to be sharpened for the first time.
The tip needs a little repair.
Lessons learned

The little mistakes, the ideas (that sometimes came too late) are collected here:

  • When using the grinding jig you can distribute the downward force between your hands and in that manner control the grinding bevel to small extend.
  • As you are grinding the bevel with the jig and the cutting edge gets thinner - make sure not to hit it (with a file handle or attachment) as the non hardened steel is soft and easy to damage as it gets thin.
  • When free-hand-filing a grind (cross-draw with a file - see Project #5 for photos) use some sort of tip protector that will not allow you to move the file beyond the tip, as on return (you are working fast and with quite some force) you will hit and badly damage the tip.
  • Grind your blade down to 0.1 - 0.2 mm from the final profile/geometry before going for HT if you do not have any powered tool for that. Hand grinding the blade after HT will require diamond plate of some sort and may take many hours of hard work to get done even with a smaller blade.
  • If you want to use some sort of powered grinding tool (like belt or disc sander) to shape the handle be prepared for LARGE amount of very fine dust that will be getting everywhere. Using some sort of vacuum cleaner attached directly to the power tool helps a lot.
  • Once you are finishing hand sanding the blade with the final grit - make sure that you start the sanding movement such that only the edge of the sanding block/holder you use has contact with the blade, otherwise you will get starting marks on the blade.
  • 400 grit finish looks good, but it is still a bit too coarse (depth of the scratches) in the sense that dirt/gunk/fingerprints are harder to wash off. Next time I will go to around 1200.
  • If you hand finish the blade before handle is attached (WA or western/scales) you can make sure that there will be no starting marks on the exposed part of the blade.
  • Be careful when drilling narrow holes to stabilized wood - the drill bit may get stuck. That happened to me and I did not manage to free it. All my efforts led to breaking it and loosing the  ferrule.

A few photos of the finished knife

I kept the butt shaping simple - just took the edges off.

Ready to use.

Next to Carter funayuki. Yes - the handle I made is a little too large for the knife.

Choil shot - Carter funayuki on the left for comparison
Thanks for reading this long post :)


  1. Nice!!! Why did you leave the handle a bit square and not go for the full octagon?

    1. Thank you :) I guess the main reason is the fact, that it was the very first WA handle I made and I was happy that it had half-reasonable shape. I have sanded to a bit smaller size since and will probably sand it once again. It is somehow way too easy to make the handle too large :)