Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
--Specifications --
The blade is 0.075" thick, 1.1" wide, and weighs 60 g. The edge is 0.005-0.010" thick, at 19.5 +/- 1 degrees per side. The primary grind is 0.54" wide, sabre-flat on one side, dual flat on other side (another flat grind goes from the middle up to the spine). The edge is uniformly sharpened along its length to a fine polish (< 5 micron), push cuts photocopy paper stright down, and can scrape shave a little.
--Stock testing --
The sharpness was tested by push cutting light thread, and slicing 1/4" poly under 1000 g of tension. On the thread ~135 g of force was required near the base of the blade, increasing to ~205 g near the tip. On the poly the same trend was noted, ~0.75 cm was required near the base, and ~1.4 near the tip.
On 3/8" hemp, doing a straight push cut, the ceramic blade took ~36 lbs to cut through the cord near the base of the blade , up to ~31 lbs near the tip where the edge was slightly thinner. The blade had no real aggression on a slice, the same amount of force had to be used.
I'll put these into perspective shortly.
--Edge retention in Kitchen use --
The blade was used mainly compared to a Henckels paring knife. I modified the paring knife some time ago to increase its cutting ability significantly over the NIB geometry (~2:1). The edge is now 0.011" thick by 0.051" wide which is 6.2 degrees per side . It has a slight micro-bevel of 22 degrees per side either with a fine ceramic (<5 micron) or 600 grit DMT finish. When sharpeing, the edge bends really easily, you have to go very light on the ceramic rod to avoid burring it totally to one side.
When sharpened to a fine push shaving with the ceramic rod, the Henckels easily push cuts right into photocopy paper. On the thread it took 148 +/- 13 g, and on the poly it was 0.060 +/- 0.04 cm. Thus, the ceramic was just as sharp near the base of the blade, but slightly blunter as you run out towards the tip. The cutting ability is very close between the two as well as the Henckels takes 32 - 24 lbs (base to tip), on the hemp with a push cut, and 20 +/- 1 lbs on a two ince slice.
The Henckels doesn't well represent as sharp as a knife can get . Because of the low hardness, it is difficult to push the sharpness beyond a given level as when you try to refine it, you end up just pushing it around. To illustrate the kind of sharpness which is possible with a high end steel knife I then sharpened a custom MEUK in 52100 steel heat treated by Ed Caffrey. The edge is between 0.005 - 0.010" thick and is ground at ~15 degrees per side. The edge was set with waterstones and finished with 10 passes per side with leather loaded with a 0.5 micron CrO buffing compound. The blade was now significantly sharper than the Henckels. It only took 115 +/- 11 g on the thread, and a minimal 0.50 +/- 0.07 cm on the poly.
<table cellpadding =10>
<caption>Initial Edge sharpness</cation>
<tr><th>Knife</th><th>Thread (g)</th><th>Poly (cm)</th></tr>
<tr><td>OK-45</td> <td>135-205 </td><td>0.75 - 1.4</td></tr>
<tr><td>Henckels</td><td>148 (13) </td><td> 0.60 (0.04)</td></tr>
<tr><td>MEUK</td> <td>115 (11) </td><td> 0.50 (0.07)</td></tr>
</table>
As a stock test I used the above blades to do 250 cuts through Rhubarb. All blades could cut the Rhubarb well when it was layed flat. The higher initial sharpness of the MEUK made no practical difference cutting this specific material. With each blade, a simple draw cut severed the vegetation easily. However when the rhubarb was stacked, the MEUK fell significantly behind as a lot of pressure had to be applied. Its much greater stock thickness was for this cutting more critical than the high initial sharpness. A more coarse finish is actually better here. A cheap paring knife I had on hand with a 600 grit DMT finish easily outsliced all three blades.
<table cellpadding =10>
<caption>Edge sharpness after the rhubarb cutting</cation>
<tr><th>Knife</th><th>Thread (g)</th><th>Poly (cm)</th></tr>
<tr><td>OK-45</td> <td>200 ( 5) </td><td> 0.95 (0.11)</td></tr>
<tr><td>Henckels</td><td>190 (12) </td><td> 0.75 (0.06)</td></tr>
<tr><td>MEUK</td> <td>205 ( 5) </td><td> 1.10 (0.07)</td></tr>
</table>
After the cutting the Henckels shaved the best followed by the OK-45. The MEUK could not shave at all, even scrape. All blades could still push cut photocopy paper at ~45 degree angle. The MEUK took a visible patina during the cutting (Rhubarb is acidic), which is probably what lead to its more extensive blunting, the edge had several damaged spots up to 0.002" deep, and extensive smaller ones. The Henckels only has one small damaged area about 0.001" in size, and the OK-45 is uneffected except for one spot 0.002" deep by about 0.02" cm long .
--Misc Kitchen use --
The ceramic utility knife was then used for several weeks in the kitchen cutting along side other blades to guage its abilities. The sharpness was enough to cut most materials very well, alongside the better steel blades I had (with fine polishes). Breads, meats (including trimming fat), vegetables and fruits were no problem. The sharpness of the ceramic was also retained through several sharpenings of various steel knives, so the edge retention of the ceramic blade is indeed many to one over steel knives. However it should be noted that with the use of a smooth steel (or fine ceramic or diamond rod), the sharpness of a steel knife can be maintained to a very high level with less than a minutes work at the start of the day.
There were however a few foods that the higher sharpness of some of the steel knives did induce greater performance, slicing potatoes for example. The softer the material, the more sharpness tended to come into play. There were also some foods that the ceramic knife did not cut well at all. Tomatoes, plums and basically anything with a tough skin and soft underneath. If the fruits were fresh, and thus elastic, then the knife could handle them generally ok. However if they were at all a little soft, then this bit of give would prevent any cutting and you would have to mash them. Really hard crusty breads were also a problem, the edge would tend to just skate over the crust. A steel knife with a high polish won't cut any of this well either, you want either a serrated knife, or one with a coarse finish. A 600 grit DMT rod gives enough aggression for most of these problem foods.
As a side note, after a session of heavy cutting, I noted that the OK-45 edge had rolled significantly and would in fact only shave on one side. However about eight hours later when I went to quantify the edge a little the shaving ability had returned to both sides and it was back at the factory level again. I would have tended to think it was just my imagination except I have quantified this with steel blades, this is the first time I have seen it with a ceramic. This is a well known property of straight razors, and why it is often suggested that you have at least two and use them in rotation.
--Misc commentary --
This knife has a very ergonomic and comfortable handle. I much preferred it to the squarish Henckels. It is also very light and thus generates no fatigue no matter how it is gripped. I used it for many tasks for which you would generally use a paring knife (peeling potatoes), and it did them all very well being so easy to handle. The fact that the blade could not corrode was also a nice change of pace, not having to rinse a knife after cutting acidic vegetables could be a serious advantage to some. The only real serious problem is the low durability. It can't be used for bone cutting, even light work (splitting a chicken, which the Henckels paring knife will handle with just some edge flattening). However I did not hold back on any of the vegetable cutting, even rocking through some thick turnips (better off with a chef's knife here obviously), and the blade held up fine.
--Sharpening--
The blade didn't dull significantly during the above described use, however after reading some comments on the web about touching up ceramic knives on ceramic rods I gave the blade a couple of passes the same fine ceramic used in the above. The edge got broken apart for the entire length showing chips from 0.002"- 0.004" deep. A 600 grit diamond rod improved the finish, but left it many times rougher than it would a steel blade. I think that the rods were exerting too much pressure on the edge. I then used a 1200 grit DMT pad which isgnificantly improved the level of the finish. However it is still multiple times as coarse as it would be on a steel blade.
With the 1200 DMT finish, the knife can just slice paper. It is much duller than the NIB condition, and takes 600+ g to cut the thread. You might be curious if the slicing ability has been improved with the more coarse finish, I was. I tried it out on some tomatoes. It didn't cut them as well as it did when new. The edge doesn't seem to take micro teeth like steel blades do when left with a rough finish. I am going to get some fine diamond paste and see if that improves the edge further.
--Suggestions--
Considering that this is a light use knife, it might be worthwhile to try acute edge geometry, maybe even japanese style to increase the cutting ability.
--Overview --
NIB sharpness : good
cutting ability : very good
Handle ergonomics / comfort: very good
Handle security : good
Corrosion resistance : excellent
Edge retention : excellent
Durability : dismal
Ease of sharpening : N/A*
*I'll wait until I get the diamond paste to rank it.
Grading system :
Excellent - sets a standard
Very good - may be enough to make you want to buy the knife on its own
Good - makes you take note
Average - expected
Fair - doesn't effect performance too badly
Poor - could be enough to make you want to not buy the knife
Dismal - the performance is basically scuttled if it depends at all on this attribute.
The blade is 0.075" thick, 1.1" wide, and weighs 60 g. The edge is 0.005-0.010" thick, at 19.5 +/- 1 degrees per side. The primary grind is 0.54" wide, sabre-flat on one side, dual flat on other side (another flat grind goes from the middle up to the spine). The edge is uniformly sharpened along its length to a fine polish (< 5 micron), push cuts photocopy paper stright down, and can scrape shave a little.
--Stock testing --
The sharpness was tested by push cutting light thread, and slicing 1/4" poly under 1000 g of tension. On the thread ~135 g of force was required near the base of the blade, increasing to ~205 g near the tip. On the poly the same trend was noted, ~0.75 cm was required near the base, and ~1.4 near the tip.
On 3/8" hemp, doing a straight push cut, the ceramic blade took ~36 lbs to cut through the cord near the base of the blade , up to ~31 lbs near the tip where the edge was slightly thinner. The blade had no real aggression on a slice, the same amount of force had to be used.
I'll put these into perspective shortly.
--Edge retention in Kitchen use --
The blade was used mainly compared to a Henckels paring knife. I modified the paring knife some time ago to increase its cutting ability significantly over the NIB geometry (~2:1). The edge is now 0.011" thick by 0.051" wide which is 6.2 degrees per side . It has a slight micro-bevel of 22 degrees per side either with a fine ceramic (<5 micron) or 600 grit DMT finish. When sharpeing, the edge bends really easily, you have to go very light on the ceramic rod to avoid burring it totally to one side.
When sharpened to a fine push shaving with the ceramic rod, the Henckels easily push cuts right into photocopy paper. On the thread it took 148 +/- 13 g, and on the poly it was 0.060 +/- 0.04 cm. Thus, the ceramic was just as sharp near the base of the blade, but slightly blunter as you run out towards the tip. The cutting ability is very close between the two as well as the Henckels takes 32 - 24 lbs (base to tip), on the hemp with a push cut, and 20 +/- 1 lbs on a two ince slice.
The Henckels doesn't well represent as sharp as a knife can get . Because of the low hardness, it is difficult to push the sharpness beyond a given level as when you try to refine it, you end up just pushing it around. To illustrate the kind of sharpness which is possible with a high end steel knife I then sharpened a custom MEUK in 52100 steel heat treated by Ed Caffrey. The edge is between 0.005 - 0.010" thick and is ground at ~15 degrees per side. The edge was set with waterstones and finished with 10 passes per side with leather loaded with a 0.5 micron CrO buffing compound. The blade was now significantly sharper than the Henckels. It only took 115 +/- 11 g on the thread, and a minimal 0.50 +/- 0.07 cm on the poly.
<table cellpadding =10>
<caption>Initial Edge sharpness</cation>
<tr><th>Knife</th><th>Thread (g)</th><th>Poly (cm)</th></tr>
<tr><td>OK-45</td> <td>135-205 </td><td>0.75 - 1.4</td></tr>
<tr><td>Henckels</td><td>148 (13) </td><td> 0.60 (0.04)</td></tr>
<tr><td>MEUK</td> <td>115 (11) </td><td> 0.50 (0.07)</td></tr>
</table>
As a stock test I used the above blades to do 250 cuts through Rhubarb. All blades could cut the Rhubarb well when it was layed flat. The higher initial sharpness of the MEUK made no practical difference cutting this specific material. With each blade, a simple draw cut severed the vegetation easily. However when the rhubarb was stacked, the MEUK fell significantly behind as a lot of pressure had to be applied. Its much greater stock thickness was for this cutting more critical than the high initial sharpness. A more coarse finish is actually better here. A cheap paring knife I had on hand with a 600 grit DMT finish easily outsliced all three blades.
<table cellpadding =10>
<caption>Edge sharpness after the rhubarb cutting</cation>
<tr><th>Knife</th><th>Thread (g)</th><th>Poly (cm)</th></tr>
<tr><td>OK-45</td> <td>200 ( 5) </td><td> 0.95 (0.11)</td></tr>
<tr><td>Henckels</td><td>190 (12) </td><td> 0.75 (0.06)</td></tr>
<tr><td>MEUK</td> <td>205 ( 5) </td><td> 1.10 (0.07)</td></tr>
</table>
After the cutting the Henckels shaved the best followed by the OK-45. The MEUK could not shave at all, even scrape. All blades could still push cut photocopy paper at ~45 degree angle. The MEUK took a visible patina during the cutting (Rhubarb is acidic), which is probably what lead to its more extensive blunting, the edge had several damaged spots up to 0.002" deep, and extensive smaller ones. The Henckels only has one small damaged area about 0.001" in size, and the OK-45 is uneffected except for one spot 0.002" deep by about 0.02" cm long .
--Misc Kitchen use --
The ceramic utility knife was then used for several weeks in the kitchen cutting along side other blades to guage its abilities. The sharpness was enough to cut most materials very well, alongside the better steel blades I had (with fine polishes). Breads, meats (including trimming fat), vegetables and fruits were no problem. The sharpness of the ceramic was also retained through several sharpenings of various steel knives, so the edge retention of the ceramic blade is indeed many to one over steel knives. However it should be noted that with the use of a smooth steel (or fine ceramic or diamond rod), the sharpness of a steel knife can be maintained to a very high level with less than a minutes work at the start of the day.
There were however a few foods that the higher sharpness of some of the steel knives did induce greater performance, slicing potatoes for example. The softer the material, the more sharpness tended to come into play. There were also some foods that the ceramic knife did not cut well at all. Tomatoes, plums and basically anything with a tough skin and soft underneath. If the fruits were fresh, and thus elastic, then the knife could handle them generally ok. However if they were at all a little soft, then this bit of give would prevent any cutting and you would have to mash them. Really hard crusty breads were also a problem, the edge would tend to just skate over the crust. A steel knife with a high polish won't cut any of this well either, you want either a serrated knife, or one with a coarse finish. A 600 grit DMT rod gives enough aggression for most of these problem foods.
As a side note, after a session of heavy cutting, I noted that the OK-45 edge had rolled significantly and would in fact only shave on one side. However about eight hours later when I went to quantify the edge a little the shaving ability had returned to both sides and it was back at the factory level again. I would have tended to think it was just my imagination except I have quantified this with steel blades, this is the first time I have seen it with a ceramic. This is a well known property of straight razors, and why it is often suggested that you have at least two and use them in rotation.
--Misc commentary --
This knife has a very ergonomic and comfortable handle. I much preferred it to the squarish Henckels. It is also very light and thus generates no fatigue no matter how it is gripped. I used it for many tasks for which you would generally use a paring knife (peeling potatoes), and it did them all very well being so easy to handle. The fact that the blade could not corrode was also a nice change of pace, not having to rinse a knife after cutting acidic vegetables could be a serious advantage to some. The only real serious problem is the low durability. It can't be used for bone cutting, even light work (splitting a chicken, which the Henckels paring knife will handle with just some edge flattening). However I did not hold back on any of the vegetable cutting, even rocking through some thick turnips (better off with a chef's knife here obviously), and the blade held up fine.
--Sharpening--
The blade didn't dull significantly during the above described use, however after reading some comments on the web about touching up ceramic knives on ceramic rods I gave the blade a couple of passes the same fine ceramic used in the above. The edge got broken apart for the entire length showing chips from 0.002"- 0.004" deep. A 600 grit diamond rod improved the finish, but left it many times rougher than it would a steel blade. I think that the rods were exerting too much pressure on the edge. I then used a 1200 grit DMT pad which isgnificantly improved the level of the finish. However it is still multiple times as coarse as it would be on a steel blade.
With the 1200 DMT finish, the knife can just slice paper. It is much duller than the NIB condition, and takes 600+ g to cut the thread. You might be curious if the slicing ability has been improved with the more coarse finish, I was. I tried it out on some tomatoes. It didn't cut them as well as it did when new. The edge doesn't seem to take micro teeth like steel blades do when left with a rough finish. I am going to get some fine diamond paste and see if that improves the edge further.
--Suggestions--
Considering that this is a light use knife, it might be worthwhile to try acute edge geometry, maybe even japanese style to increase the cutting ability.
--Overview --
NIB sharpness : good
cutting ability : very good
Handle ergonomics / comfort: very good
Handle security : good
Corrosion resistance : excellent
Edge retention : excellent
Durability : dismal
Ease of sharpening : N/A*
*I'll wait until I get the diamond paste to rank it.
Grading system :
Excellent - sets a standard
Very good - may be enough to make you want to buy the knife on its own
Good - makes you take note
Average - expected
Fair - doesn't effect performance too badly
Poor - could be enough to make you want to not buy the knife
Dismal - the performance is basically scuttled if it depends at all on this attribute.
).
