Beiträge von kwakster

This is how i received the knife back after about a month of use in a commercial kitchen, and only after the Chef cut up several Italian artisan breads with almost rock hard crusts, which of course damaged the very hard & very thin edge.
There were both chips and rolls in the apex, but only one chip extended a hair past the polished bevels (which were starting to develop a nice blueish patina).
The undamaged parts of the apex however could still shave the hair on the back of my hand on skin level reasonably well.
(click 2 x on each pic for more detail)

The edge was restored freehand with the help of my Tormek T7 with it's SB-250 stone, refined with a Paper Wheel coated with 3.0 micron diamond compound, and deburred with a second Paper Wheel coated with 1.0 micron diamond compound, and the new apex now measures an almost exact 20 degrees inclusive.

According to the Chef this Kohetsu HAP40 is the best knife he ever owned, and from now on he will refrain from cutting those hard crusted breads with it.
He also intends to buy a nice hinoki cutting board.

The knife at this moment.
(Click 2 X on the pics for more detail)

Yesterday i continued playing / testing / finetuning the knife somewhere in the Veluwe nature reserve.
About a week ago i thinned the blade just a bit more and the new apex now fits neatly in the 25 degrees slot of my Tormek WM200, and so far the knife seems to be able to handle that angle without any problem when chopping various kinds of mainly green wood.
No rippling and no catastrophic edge failures.
The only visible damage i could see afterwards when i got home was caused by the tiny sand particles which are omnipresent in and on practically all the wood in the reserve, and which cause those telltale minute dents in the apex.
Sometimes a bit more, sometimes a bit less, depending on how close the chopped wood was located near the sand dunes.

But after about 10-15 minutes of stropping on a piece of MDF coated with 1.0 micron diamond compound & checking with my loupe all damage was gone and the apex was hairwhittling sharp again.
I intend to find out how often i can get away with just stropping the edge in this manner before i need to sharpen it again, which i do on a used sheet of 400 grit wet & dry on top of a big piece of fiber reinforced & semi-hard rubber conveyor belt.
On the wet & dry paper i use WD40 spray, which makes the silicon carbide grit cut more effectively, it keeps the swarf floating in suspension better than water, and it prohibits flash rust on the carbon steel.

Iirc the handle received 5 coats of IKEA cutting board oil, and after a long period of drying 1 more coat of Granger's wax to seal the wood.
Due to the contouring the handle now offers 3 hand positions:
- Exactly in the middle for a neutral grip (for general cutting)
- Against the integral pommel for maximum chopping power (for thick branches & smaller trees)
- Up front held loosely with your pointing finger in the cut-out for tip speed / snap cuts (for brambles, twigs, and thinner branches)

So far i have absolutely nothing to complain about this more than 50 year old knife, and it has already proven itself as an excellent chopper made in very well hardened steel.

Immobilized the guard with two narrow shards of brass sheet (one on each side), which were lightly tapped all the way to the tang using a small hammer & small section of a snap-off blade which i ground blunt & square.
The larger piece of brass sheet in the pictures is what was left after i used a pair of scissors to cut the two shards from, each one about a millimeter wide.
Also rounded the edges on the brass guard and polished it a bit.

At this point in time and after just a short period of testing i would say that the edge is quite durable.
Not so much in keeping a super high sharpness , think hairwhittling / treetopping / arm hair shaving (although i plan to experiment further with various other sharpening methods), but the material surely seems to be able to hold a good useable edge for actual kitchen use.
Although titanium at 48 HRC isn't very hard itself, in these blades it acts as the matrix to hold the diamond & ceramic particles, which are responsible for the very high wear resistance, and i think that together with the other alloying ingredients this provides for enough firmness for the edge apex so that it doesn't fold over or chips easily in actual use.
So far i haven't seen it anyway.

Now at the moment i'm experimenting with regrinding the blade as the factory grind was a bit too thick for my taste, plus i wanted to see if it was at all possible.
The factory edge measured somewhere between 25 and 30 degrees inclusive, with a thickness behind the edge of 0,54 mm.
Now the blade is a very shallow convex with something that resembles a zero edge, and the new apex fits in the 20 degrees inclusive slot of my Tormek WM 200 Angle Master.
Besides the fact that the knife now cuts in an entire different league the edge so far seems to hold up in both my kitchen use as well as in cutting quite a bit of cardboard without it folding over or chipping.

Besides being 100 % rust proof and the edges having a very high wear resistance the blade material also has active anti-bacterial properties due to silver particles in the alloys of both the Diamond Titanium & the Cera Titanium line.

Japan Food Research Laboratories http://www.jfrl.or.jp/e/ did a test where E-Coli bacteria were put on different blade materials, and then microscopic pictures were taken at various time intervals to see what happened.
I found the pic below on a German website.
The first row shows a Forever titanium blade, and the second row shows a stainless steel one.

The factory edge on the knife was only copy paper slicing sharp, and when i looked at the apex through my Victorinox loupe i could see that it was more or less micro-serrated over it's entire length (due to it being rather coarsely sharpened at the factory)
Trying to improve upon the sharpness (in my case with Paper Wheels coated with various diamond compounds) turned out to be possible, and after 15, 6, and 3 micron those micro-serrations disappeared and the apex became clean and fine enough to shave the hair from the back of my hand at an inclusive edge angle of between 25 and 30 degrees.
Even though motorized the process was very time consuming, and with each finer diamond compound things slowed down even more.

All the work turned out pretty useless in the end: after using the knife just one time on a good wooden cutting board to cut up all the ingredients for a big pasta salad (various onions, bell peppers, garlic & broccoli) the apex sustained damage in some places (seen through the loupe), and i think i saw both microchipping & rolling (not sure)
My guess is that just like it's Cera-Titan counterpart the Dia-Titan alloy & high sharpness polished edges don't go together well, and it probably does better and longer with a less refined edge.
Removing the damage and resharpening to factory sharpness however was quite easily done with a DMT Diafold Fine/Red, and afterwards i did a little cardboard cutting test.

With the new & less refined edge the knife sliced a measured 100 meters or 328 feet of double walled cardboard plus 70 meters or 229 feet of single walled cardboard without tearing, and at that point i ran out of cardboard.
Afterwards when seen through my loupe the edge showed no damage other than a very narrow line of light over it's entire length, and i'm convinced it could have sliced a whole lot more cardboard.
The edge is also still sharp enough to slice copypaper.

I will now resharpen the edge with just the DMT Diafold Fine/Red and continue to use it in our kitchen.

Besides several knives i received from Forever Japan for testing i also got this pair of ceramic scissors.
Someone i know who makes custom swim wear & ballroom clothing for a living is going to use it for a while, and any feedback i get from her will be posted in this thread.
If no massive chipping or breakage occurs during that time i might even try to resharpen it later on.
You can click 2 X on each pic for more detail.

Text from the Forever website:

" FOREVER ceramic scissors are available in 3 blade sizes – 50mm, 60mm and 80mm – and in both white and black blades.
Ceramic scissors are lightweight, handy, easy to clean and will never rust.
These scissors are suitable as kitchen/household scissors and for use in more specialist applications.

Kitchen/household scissors
Can be used to cut lettuce, herbs and meat.
Ceramic is a chemically inert material – it will not cause food to turn brown or leave a metal smell, maintaining the appearance and natural odor of food.
Also suitable for cutting food wrapping and other plastic packaging or as general household scissors.

Kevlar and other fabrics
Kevlar fabrics and other fibers soon cause steel scissors to become blunt but FOREVER ceramic scissors can cut such materials while still retaining their sharpness over a long period.
Since ceramic is non-magnetic, these scissors can be used to cut magnetic media without causing damage or contamination."

Specs:

Overall length : 8.66 inch (22,0 cm)
Sharpened edge length: 3.27 inch (8,3 cm)
Material: high density white ceramic made from zirconium oxide powder
Handle material: black plastic
Weight: 86 grams

More info: http://forever-k.com/en/ceramic/

Yesterday i received two of these Kohetsu HAP40 Santoku's from Chefknivestogo.com, a dependable US dealer for kitchen knives.
One of these will go to a Chef i know who has no experience ordering knives from abroad, and the other one will probably go on sale on the Dutch forum.​

As often with Japanese knives the factory edges need some work to get them truly sharp, and these Kohetsu's were no exception.
One was just sharp enough to slice copypaper, the other reluctantly shaved a few hairs from my hand, and both of them had a few tiny burr remnants clinging to the apex.
Now both me and the new owner have zero experience with HAP40, so it will be a bit of a learning journey to finetune the edge into what works best & longest for him.

For it's first sharpening i chose to just leave the factory edge angle of between 17.5 & 20 degrees inclusive (!) intact and just resharpen the existing narrow V-bevel with 3 micron diamond compound on a Paper Wheel (with such a small edge angle this actually provides for an ever so tiny, but just visible burr), and deburr with 1 micron diamond compound on a second Paper Wheel.
With the naked eye it looks like nothing was done to the knife, but the new edge can whittle a chest hair towards the hair point and slice a paper towel clean.
Now we have to find out if the new owner can work with it, and what's especially important; for how long exactly before it needs resharpening.
My guess is that eventually he will settle upon a bit coarser edge, but we will see.

Specs:

Overall length: 29,5 cm
Blade length: 18,0 cm
Useful edge length: 17,4 cm
Blade thickness: max 2.06 mm
Steel: Laminated HAP40
Hardness: 65 HRC
Blade: double sided convex grind with half-sided convex bevel and a narrow V-bevel on top which forms the actual edge.
Edge angle: between 17,5 and 20 degrees inclusive (measured with Tormek WM200 Angle Master)
Handle material: Pakkawood
Weight: 170 grams

For resharpening Forever recommends their own diamond sharpener.
In Europe you can get it on Amazon etc under the Victorinox name.
(Forever supplied to them and they sold it under their own name)

The performance in our home kitchen so far is quite positive i would say, and things that stand out for me are the ultra low weight and the aggressiveness of the factory cutting edge, even though that edge is only copy paper slicing sharp.
Since one of these knives is going to be tested for some time by a real Chef who is used to truly sharp steel knives (which i sharpen for him) i want to find out if i can improve upon the factory sharpness of this material.

These are the Diamond Titanium knives i received, minus one Chef knife which i already sent through to one of the admins of British knife forum Edgematters.uk, to use as he thinks best.
Soon one of the remaining new models is going to be used for a while by a professional sous-Chef in a busy restaurant kitchen, and his report will be written down later on in this thread.

One santoku is already in use in our own kitchen & i use it for sharpening practice.
The text on the blade is already fading due to handling, but to me that doesn't matter.

The still new & unused Santoku model:

Specs:

Overall length: 32,1 cm (12.64 inch)
Blade length: 18,7 cm (7.36 inch)
Blade thickness: 1,51 mm
Blade material: titanium alloy (48 HRC) with diamond particles, ceramic particles, and silver.
Handle material: Plastic
Weight: 84 grams

The still new & unused Chef knife:

Specs:

Overall length: 35,0 cm (13.78 inch)
Blade length: 21,5 cm (8.46 inch)
Blade thickness: 1,78 mm
Blade material: titanium alloy (48 HRC) with diamond particles, ceramic particles, and silver.
Handle material: Plastic
Weight: 94 grams

In the past i did 2 reviews on different Forever kitchen knives, 1 x ceramic, and 1 x titanium hybrid, both for myself and forum members to enjoy on various international knife forums.
A few weeks ago i decided to send the links to those reviews to Forever head quarters in Japan to see if i would get a reaction or not.
To my surprise i was contacted a few days later by a friendly Englishman, who told me that they had read my reviews with interest and we got to talk a bit about their products.

Well, to make a long story even longer he offered to send me several Forever knives as samples and told me that i could use any of them how i'd think best, and that he hoped this would be somehow beneficial for them as a company (Forever is still a virtual unknown in the Netherlands and no shops carry their knives.)

Just before my hodliday i received the package, and in it were several Diamond Titanium knives (as well as some ceramic cutlery items, but this thread is solely about the Diamond Titanium models)

These pics i've taken from the internet:

Since the brass guard was a bit loose, i'm experimenting to find out if shimming it with a few small pieces of brass sheet is a viable option.
While it works very well to immobilize the guard 100 % even during maximum force chopping (tested the knife again in the woods yesterday), the shims need to be a bit smaller to be totally invisible.

The 1095 Cro-Van blade steel also holds up well; after taking down several thin trees / thick saplings (think upper arm size) the edge can still shave the hair from my leg.
And this is with a 400 grit wet & dry SiC finish deburred with 1.0 micron diamond compound on MDF.

The knife as it looks at the moment.
Reground the already convex blade but now to a zero edge of about 30 degrees inclusive & contoured the handle.
Still have to work on the swedge & guard and restitch the sheath.

One of my recent finds, an early Western Bowie from around 1965:

After testing the knife a few times in the woods i modified the handle a bit more to my liking.
Next i recolored the leather, and soon a few layers of Granger's wax will follow.

The knife as it looks at this moment.
I made the guard a bit smaller, rounded the edges, then sanded & polished the brass a bit on a felt wheel with some green compound.
Glued it back in place with 2-component epoxy, then glued all the washers together on the tang and put the pommel back on with some Teflon tape on the threaded tang end.

Currently busy making the new guard from a flat piece of brass i had lying around from a previous project.
The center hole that was already there was enlarged with a file to fit this knife, the rough outer shape was cut out with a small hacksaw, the result was ovalized on a normal bench grinder, after which the outer edge was ground square on the Tormek.

More testing is needed to decide upon the final size & shape of the guard, so it's likely there will be changes in the near future.
The old guard was reshaped & reused as a cover plate on top of the new guard, but i still have to fit things a bit better.
Put the knife together temporarily for the pics.

Taking the handle apart: