Beiträge von kwakster

My workplace is in the back of our small cellar, which we also use to store our bikes and other stuff we don't use on a daily basis.
So nothing fancy as you can see

Overview:

My Tormek T7 wetsharpener fitted with an SB-250 Black Silicon stone:

My red Creusen DS7500TS benchgrinder with Paper Wheel coated with 220 grit SiC on the left, and my still experimental Rubber Wheel coated with 230 grit diamond powder on the right:

My collection of different Paper Wheels & Rubber Wheels:

Most edges are indeed freehanded on the Tormek and the various Paper Wheels/Rubber Wheels, but for certain types of edges like tanto's (as well as scissors and chisels) i use the Tormek with jigs, like on this Strider GB:

As you can see i didn't refine the scratch pattern on purpose (as i think it looks good on a knife like this), only removed the burr on the Tormek leather honing wheel, followed by some stropping on a leather handstrop coated with 6 micron diamond paste to create a slightly convex microbevel.
The straight part of the edge now measures around 25 degrees inclusive while the slanted part is about 30 degrees inclusive.

The (semi-polished) mirror edges i put on knives are best maintained on hard leather or MDF strops coated with some diamond compound, but on many working knives i don't put a mirror edge.
Most Chef knives for instance i do for restaurants only get sharpened on the Tormek with the silicon carbide stone graded to about a 1000 grit, as based on feedback that finish seems to work both the best & the longest.

Here's an example of how i use the diamond powder from Yuriy.

The knife is made by Ewout vd Gronden (E.A.G. Knives), a Dutch part-time knife maker who spends a lot of thought, time and effort into making about two knives a month.
For steels he likes to use D2 and N690Co which he hardens himself with very good results (i've tested a few of them in the field and provided him with feedback)
After he finishes a knife he sends it to me to give it the final edge.
He also lets me know his wishes regarding edge angle & edge finish, and i go to work.

This is one of his larger field grade knives i did recently, and the picture was taken by the maker before i put on the edge.
Steel is N690Co, blade is 18 cm long, and the handle is canvas Micarta.

These are pics taken by me with it's new edge, in this case of a pre-specified and almost exact 35 degrees inclusive.
Bevels were ground with the Rubber Wheel coated with 230 grit diamond powder, after which i only removed the tiny burr with a Paper Wheel coated with 1 micron diamond compound.
This provides for a strong edge that is literally treetopping sharp along it's entire length, yet still has a lot of bite.
(pics can be clicked 2 x to get a better view of the scratch pattern the 230 grit diamond powder creates)

Since i'm a fan of using diamond products for sharpening & polishing knife edges i'm always looking for good sources.
A few months ago i found this small US company: http://techdiamondtools.com, and they also have a Facebook page: https://www.facebook.com/lapidarypaste

Owner: Yuriy Ma
Address: 10511 Glencoe Drive
Cupertino, California
95014 USA

I exchanged a few e-mails with Yuriy and bought 100 carat (about 20 grams) of 230 grit diamond powder from him, paid with Paypal and received my order in about a week from the US, neatly packaged in a double plastic pouch inside a small bubble envelope.
I'm currently using the powder glued to the surface of a Rubber Wheel for sharpening ceramic knives and various high carbide steels, and i must say with very good results so far.
When my stock of various diamond compounds runs out i'm also going to order some from here.

Now i'm not sure if i put this in the right place on the forum, i just wanted to share this useful information with my fellow knife afi's here.
If it's not allowed please move it elsewhere or remove.

For the last month and a half i've used the Forever Titanium Hybrid knife in our kitchen almost exclusively (coupled with a reground Spyderco paring knife), and i must say i'm quite pleased with it.
The model & size are very handy for what i use a kitchen knife for, it cuts very well because of the thin blade geometry & 25 degrees inclusive edge, and the blade material keeps a slicing edge for a long time.
Today i resharpened it for testing purposes, even though the old edge was still sharp enough to cut tomatoes.
As far as i could see through my Victorinox loupe the blunting mechanism seems to be microchipping, but this happens only very slowly and on a very small scale.
The chips aren't visible with my naked eye and are actually helping to prolong the aggressive slicing edge this material naturally seems to like.

Since i wanted to find out how silicon carbide would do with this blade material i took it to my trusted Tormek T7 fitted with the SB-250 Black Silicon stone, and to keep it short: the stone ate the Cera-Titan for breakfast.
My stone is graded to about a 1000 grit, and in only a few slow passes per side i had a nice burr.
Removing that burr took noticeably more time (the titanium matrix is very resilient), but with some 1 micron diamond compound on the leather wheel i managed to slowly abrade it away.
The resulting edge could just shave the hair on the back of my hand on skin level, which differs from the same sharpening procedure done on a good VG10 kitchen knife, as that almost always produces a treetopping sharpness.
Now i haven't tested this edge in our kitchen, just cut some triple, double, and single layer toilet paper, which it all did just fine.

I then proceeded to refine the edge with 15, 6, 3, and 1 micron diamond compound, all on dedicated Paper Wheels, and the edge can now whittle one of my chest hairs in the direction of the root, not towards the hair point.
It also slices single layer toilet paper very well.
Maybe the material can get even sharper with more refinement and/or different methods, i don't know, but i'm also not sure if that would even be useful, knowing how this material tends to behave.
My guess is that the current sharpness will also vanish quickly again to settle for a long lasting working edge, but i want to find out if the extra refinement steps make any difference in that degrading process.
My plan is to use the knife with this edge until i can no longer slice a tomato well, which to me is a good test method for a kitchen knife.
Later i also plan to lend the knife for a while to a professional Chef to see what he thinks of it, with a fresh edge of course.

Yesterday one of the Chefs i sharpen kitchen knives for on a regular basis decided to treat himself to a brand new Sebenza 25 from a well known Dutch knife shop.
As many here know the Sebenza is a beautifully designed & manufactured knife, and the model 25 may very well be considered the current king of the hill in the series.
Sadly the factory edge on the first example the Chef got to handle was just plain blunt, and upon inspection it turned out that the other 4 or 5 Sebenza's 25 that the shop had in stock suffered from a comparable bluntness.
To cut a long story short: in the end the Chef liked the knife so much that he just bought the least blunt one, while the shop assistant promised to contact CRK to see if the other knives could be sent back.

Anyway, today the Chef contacted me to ask if i could do something about the edge on his knife.
The first thing i noticed about the blade on his model 25 is that it seems to be ground a hair thinner behind the edge compared to previous Sebenza's 25 that i've handled and sharpened, and that as a result the edge bevels were quite narrow, even with a measured inclusive edge angle of 35 degrees.
The second thing i noticed (with my Victorinox loupe) was that the edge reflected light almost along it's entire length, and i couldn't even cut a piece of copy paper with it.
Now i think that the edge wasn't completely apexed, but with only my loupe to judge by i'm not 100 % sure.

In a conversation with the owner and also because the knife is brand new we came to the conclusion to give it a new edge that would resemble the factory edge as much as possible, and to make it seem as best as i could that nothing was done to the knife.
First i removed the blunt apex of the factory edge by cutting several times into a silicon carbide stone, after which i gave it a completely new edge with an experimental Rubber Wheel with 230 grit diamond powder.
Finally i removed the tiny burr with a Paper Wheel with 1 micron diamond compound.
The new edge again measures 35 degrees inclusive from heel to tip, survives a few cuts into my laminated test block without visible damage, and can still easily treetop the hair on the back of my hand.
I think the owner will be happy when he comes to collect his knife tomorrow morning.

Before sharpening:

After sharpening:

Yesterday evening i used the knife once more in the kitchen to cut a few ingrediënts (2 onions, a small box of mushrooms and 6 garlic cloves), and after this the edge was again reflecting light.
The line was again only visible through my loupe, but it was there.
The edge could no longer shave arm hair, but it still sliced a few cherry tomatoes just fine.

Now i'm not 100 % sure yet, but at this moment i no longer think the edge suffered from burr remnants, just as it didn't a few days ago.
Forever Cera-Titan seems specifically designed to have it's titanium matrix wear away relatively quickly, thereby exposing the hard particles in the apex and have them form a row of semi-sharp "microteeth".
In other words: immediately after sharpening the edge can be armhair shaving sharp, but that sharpness disappears quite fast into something you could call a toothy working edge.

Before i sharpen the knife again (this time just a little more coarse) and just because it's fun i did another cutting test, this time on cardboard.
As we all know this material comes in many forms, varying from very clean to heavily filled with clay and sometimes even metal shavings.
The box i cut up was something of an intermediate example: no Chinese firecracker cardboard, but still more than able to blunt edges on knives made from quality steel.
I cut the whole box into thin strips and then measured the total distance cut, which turned out to be 58 meters.

Now this was done with an edge that already reflected some light, but it kept neatly slicing to the end without tearing.
Under a bright light the light reflection on the edge is now just visible with the naked eye (but still very minimal), and seen through my loupe the bevels are riddled with small diagonal scratches on top of the sharpening scratches.
Yet the knife is still able to slice those same cherry tomatoes, not as neatly as for instance a freshly sharpened VG10 Tojiro DP Gyuto, but good enough.

BTW: earlier i found this description below on a Japanese website that sells these Forever Cera-Titan knives.
If the statement about the CBN and Vanadium Carbide particles holds any truth then i understand why refining the edge is so difficult,

SUPERIOR CUTTING EDGE RETENTION
The Cera-Titan stays sharper for a longer period than stainless or carbon steel knives.
CBN and VC particles in the blade provide the cutting edge and provide the Cera-Titan with superior resistance to wear.
LIGHTWEIGHT
The idea that a knife must be heavy to cut properly has been turned on its head by the Cera-Titan.
Weighs just half that of a steel knife of the same size.
RUST RESISTANT
Aggressive substances such as fruit acids and salt water that cause carbon and stainless steel knife to rust will never corrode the Cera-Titan.
NON-ALLERGENIC
Titanium is the safest of all metals and won''t cause allergic reactions.
ANTIBACTERIAL
The Cera Titan contains silver, which has been used for centuries in cutlery to prevent the spread of bacteria.

Just before putting on a whole new edge i wondered if the blunting of the edge could be the result of a tenacious burr remnant which i hadn't removed completely, also because the light reflection caused by the damage was only visible through my Victorinox loupe.
To find that out (and to save myself some work) i first tried if i could get the edge sharp again with just a Paper Wheel with 1 micron diamond compound.

And this worked: the light reflection is completely gone, the edge is again able to shave the hair on my leg in two directions & it can slice single-ply toiletpaper.
I also tested this edge by cutting several times into the edge of a piece of wood underlayment (deeper than the bevel width), and the sharpness remained unchanged.
Normally i do this test with every steel knife i sharpen, but i hadn't done it with this knife earlier for fear of fracturing the ceramic particles in the edge, which would have taken me back to square one.

The entire edge still measures 25 degrees inclusive, and one of these days i'm going to try the knife again in our kitchen to find out how this edge will fare.

Just used this Forever knife for the first time for cutting a few ingredients for a pasta meal on a well oiled endgrain beechwood board:

1 chorizo sausage in thin slices
2 onions
6 garlic cloves
1 lime

Plus: the knife cuts very nicely due to it's very low weight & the quite thin blade geometry.
Minus: the sharpness of the edge has already decreased to a point where it will no longer shave arm hair.
It now reflects light along almost the entire length, but this can only be seen through my Victorinox loupe, not with the naked eye.
I must say that during cutting those few ingredients mentioned i did not notice this decrease in sharpness.

Now i had reprofiled the factory edge to 25 degrees inclusive and refined it up to 6 micron diamond compound, while the manufacturer recommends on the box that the knife came in to sharpen the edge when necessary to 30 degrees inclusive, first on a grit 1000 stone and then on a grit 3000 stone (= just a bit finer than 6 micron)
(since the Forever knives are manufactured in Japan i assume that the JIS rating applies)

Sadly i can't read the rest of the Japanese text on the box, but my guess is that those stones would have to contain CBN or diamond, since the commonly used aluminum oxide isn't hard enough to cut the ceramic material in knives like this.

Anyway: i have to go back to my sharpening cave.
To be continued.

Today i tried my hand at sharpening the knife, and that did take me some time as the material is both hard & very wear resistant.

First i removed the "factory edge" by cutting a few times in the side of my Tormek Black Silicon stone, after which i ground a completely new edge on an experimental rubber wheel coated with 230 grit diamond powder.
Afterwards i refined it with 2 Paper Wheels, one with 15 micron diamond compound and one with 6 micron diamond compound, and then i removed the tiny (but extremely stubborn) burr with a third Paper Wheel with 1 micron diamond compound.

On every kind of steel i know of this procedure would have resulted in a semi-polished edge in which text can be read, but on this metal the edge at best just took somewhat of a satin finish:

The darker line in the edge on picture 2 is just the light playing tricks, as the whole edge looks like the wider grey area in real life.
Sharpness wise the edge can now shave the hair on the back of my hand in two directions, as well as slice single-ply toilet paper, also because the edge is still quite toothy.
Soon to be used in our kitchen.

When writing my review of the Forever SC-16WB ceramic knife (also in this forum) i found that the same company also produces titanium hybrid knives.
According to their website these blades consist of sintered titanium mixed with ceramic particles for increased wear resistance, as well as some silver for it's anti-bacteriologic properties.
Of course i had to buy one, in this case also from a Japan based E-Bay dealer for 49.99 US dollars including shipping from Japan to the Netherlands.
For testing purposes i chose one with the same dimensions as the ceramic knife i already have.

Now about 10 years ago the German manufacturer Böker seems to have used the same material in knives, only then it was called Cera-Titan, and it was sold in Europe under their own name.
Here is a picture of the Böker version with ziricote wood handle and & blade that looks very much the same like my Forever Titanium Hybrid knife:

I remember that back in the day i could not improve on the factory sharpness of the Cera-Titan material.
Never did it become sharp enough to shave armhair; slicing standard copy paper was about the best i could do with a Tormek 2000 fitted with an SG-250 stone as well as a belt sharpener with probably aluminum oxide belts (can't remember for sure).

Now the Forever website claims that their Titanium Hybrid / Cera-Titan knife performed 5 x better than a 63 HRC carbon steel knife and 42 x better than a 57 HRC stainless steel knife, and the testing to prove this was done according to international standard BN EN ISO 8442-5 (better known as the Catra test), where synthetic cards containing 5 % quartz are cut with a special machine, like in this YouTube clip:

http://www.youtube.com/watch?x…cl=84503534&v=WpIRLMdWsiE

While good Catra results are certainly nice to know, in real day-to-day use of a knife however many other variables play a significant role in how well and how long an edge performs, so i intend to find out how this titanium hybrid material will do in my own use.

The first problem encountered is the factory edge on my knife, which just as the earlier mentioned Böker example is only able to slice copy paper.
In no way is it able to shave my arm hair.
Since i don't feel like using the knife with this edge i will first try to sharpen it with my current sharpening equipment.
I will post my findings in this topic and put the knife to use in my kitchen, and my experiences there will also be posted here.

Specs:

Titanium Hybrid knife for right hand use (non-logo side is flat, while the logo side has 4 recessed area's, a wide saber grind and a 70/30 edge)
Overall length: 27,6 cm
Blade length: 15,7 cm
Blade material: Titanium Hybrid (Cera-Titan)
Blade thickness: max. 1.52 mm
Thickness behind the edge: 0.5 mm
Factory edge angle: 25/26 degrees inclusive
Edge finish: rather coarse
Sharpness: can slice copy paper
Edge irregularities can be felt on a finger nail and seen through a loupe.
Handle material: black polypropylene (heat resistant up to 120 degrees Celcius)
Weight: 71 grams

After a nice long vacation & a subsequent nasty flu it was time to go back to work, so i just finished refining the edge of this ceramic knife a bit further with 3 micron diamond compound on a Paper Wheel.

With my Victorinox loupe & strong floodlight the scratch pattern in the bevels is now very difficult to see, and the keenness of the edge has progressed just a little bit more.
For testing i sacrificed a few more chest hairs, and the edge is now able to whittle some of them in the direction of the hairpoint, while others are just cut completely through while the cut end jumps away.

One of the coming days i'm going to find out if a Paper Wheel with 1 micron diamond compound can improve the edge further.

A Strider SMF with S110V blade from a Dutch forum member.
According to my Tormek angle gauge the old edge measured +/- 40 degrees inclusive from the heel to half an inch before the tip where it changed into 45 degrees inclusive.
The owner uses this knife mostly to cut various kinds of green wood & twigs in horticulture, and he had already tried his hand at reprofiling the edge himself with a DMT Diafold.
Together we came to the conclusion that the edge could do with a full reprofiling, as well as with a finer edge finish to better suit his specific purposes.
BTW: the owner also contacted Duane Dwyer by mail, among other things to ask him about the hardness of this S110V blade, and according to Duane it measures 61 HRC.

This was the knife before sharpening:

After reprofiling & sharpening.
The new edge angle came out at +/- 32 degrees inclusive along the entire edge, and it can treetop armhair and slice single ply toilet paper.
Probably due to having the flu at the moment my hands didn't do exactly what i wanted them to do, and as a result i didn't manage to get both bevels completely symmetrical.
Grit progression: a Paper Wheel with 220 grit SiC for reprofiling, a second Paper Wheel with 15 micron diamond compound for refining, and a third Paper Wheel with 0.25 micron diamond compound for removing the tiny burr.

I do indeed

The edge has now been refined with 6 micron diamond compound on a Paper Wheel and is starting to resemble milk glass.
Although the scratch pattern can still be seen with my Victorinox loupe, it's getting difficult for my cheap camera to do the same.
Pictures were taken on the exact same spot with the same floodlight, and you can click them 2 x.

The edge can now slice single layer toilet paper cleanly, treetop the hair on the back of my hand, and whittle a chest hair towards the root.

Reprofiling the edge on the Tormek silicon carbide stone turned out to be rather easy, as the ceramic material in this knife has good grindability.
I thinned the edge just a hair to an almost exact 25 degrees inclusive, en the time needed to remove the miniscule chips was about 10-15 minutes.
Afterwards i did a first refining step with 15 micron diamond compound on a Paper Wheel, and now the edge looks like this.
I took the pic using a bit of floodlight to showcase the scratch pattern a little better (if you click 2 x):

The now ever so slight convex edge can currently shave armhair in 2 directions.
Next step will be refining it further with another Paper Wheel with 6 micron diamond compound.

The knife has been used the last couple of weeks for cutting all kinds of food, and was checked each time afterwards for edge damage as well as the ability to shave some hair from my leg.
Last night with my Victorinox magnifying glass i saw for the first time multiple microchips in the edge, and it's hairshaving ability had also noticeably decreased.
These microchips aren't visible with the naked eye, and the knife still cuts vegetables, fruit, and various meats just fine.

However, since i don't like to continue working with a ceramic knife with a microchipped edge i will give it a new & somewhat finer polished edge in the coming week to see how that will hold up.
While microchips also act a bit like microserrations improving slicing ability, they are also stressrisers in a material that can't handle that aspect too well.

The last few days i used the ceramic knife in our kitchen for cutting various types of food: a lot of onions, tomatoes, smoked ham, Dutch cheese, mozarella cheese, mushrooms, paprika's, all for use in pasta salads which we eat a lot during summer.

I noticed a few things:

- Cutting up 5 to 6 large onions with the ceramic knife didn't induce teary eyes like it would have done had i used a steel knife.
Instead i could only feel a very slight stinginess.
- Slices of mozarella cheese stick noticeably less to the ceramic knife than they do to a steel knife, and also leave much less cheese residue there.

Both with the naked eye and using my Victorinox magnifying glass i could not see any change to the factory edge afterwards, and the knife can still shave the hair from my calf.

For people who like to read more about ceramic knives: http://www.myceramicknives.com/
(imo there are bits & pieces of info not entirely correct, but overall the site makes nice reading material about the subject)

On that same site there are also tests on cutting various foods and how it affects them: http://www.myceramicknives.com/my-30-day-test

On another forum i got this question:

"Looks like a nice knife. But would you expect the knife to become dull after cutting up a ciabatta and a box of cherry tomatoes?
I have no experience with ceramic knives, so I am sorry if this sounds ignorant, but it would seem most or all kitchen knives with a decent edge would survive the ordeal?"

This was my answer:

"Crusted bread is known to be able to chip hard & thin knife edges made from quality knife steels quite easily, and for much harder but toughness lacking thin ceramic knife edges it is even more difficult.
The fact that this Forever ceramic knife suffered just one extremely minor chip and was able to slice those cherry tomatoes the way it did tells me quite a lot already."

Cutting a large Ciabatta bread with a semi-hard crust into 4 sections on a good wooden cutting board provided the edge with 1 tiny microchip just in front of the heel.
That chip is only visible through my Victorinox magnifying glass (not with my naked eye), and the rest of the edge still looks and feels unharmed in any way.
I've already made a few cheap ceramic knives lose their entire sharp edge by doing this test, and i wanted to see how this rather coarse edge would do right from the start.

After this i proceeded with cutting a whole box of cherry tomatoes.
Even with it's light weight of only 83 grams i could pinch the end of the handle between thumb and forefinger, put the tip of the knife on the cherry tomato, and slice it completely through on the wooden cutting board just before i ran out of edge length.
The last tomato was cut as easily as the first.