CPM S90V and Sharpmaker.

nozh2002

nozh2002

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I got my CPM S90V knives done. It is accidently heat treated as CPM S30V, but I was assured that it should not make much impact on blade properties because process is similar. It is tested - 59.5 HRC with 60~61 on the edge because I grinded it to thin and it cooled off faster then other perts of the blade. I start sharpening it and testing on my thread-test-installation.

After Medium rods it shows results similar to what I had for Buck Vangard, but then after Fine Rods I found degradation - Fine Rods did not show same results as on Vangard. I try resharpen it several times and have same results all the nime - Fine rods increase reading to 30 points.

It turns out that Vanadium Carbides which CPM S90V has a lot (3 times then S30V) are harder then Aluminium Oxide, as a result CPM S90V damage Sharpmaker Ceramics and Ceramics damage blade - wearing out steel so vanadium Carbides falling out of edge.

I am wondering what Edge Pro Stones have in base - diamond and Silicon Carbides should make job done. Also what japanese wetstones made of (King and Polar Bear)?

Thanks, Vassili.
 
The finer edge pro stones are AO, as are most japanese waterstones except the really coarse ones, 220 grit. You can buy really fine SiC paper (5 micron and below) on line in several places.

-Cliff
 
I gues I don't really understand what is going on during sharpening. Does carbides (Iron, Crom or Vanadium) really are "sharpened" by abrasives? Steel matrix itself wear out by abrasive particles but does real carbids (which is what - kind of grain?) cuted let say at half when abrasive particle hit it during sharpening?

How does sharpening phisics (mechanics) work?

Thanks, Vassili.
 
If the abrasive is harder than the carbides, it will sharpen the carbides too. If not, then they will just scratch the stone and fall out when the stone wears away the metal that is holding them. Vanadium carbide is harder than chromium oxide and most types of aluminum oxide (maybe a pure sintered ruby stone would be harder, but I can't find hardness values on the same scale to compare). Cubic boron carbide, nitride and diamond are harder than Vanadium carbide so things made from them will work. Some types of silcon carbide are harder and some are softer so you'd have to try SiC stones.

Most of the finer waterstones are made with aluminum or chromium oxide. You might find some with fine silicon carbide that will work. (try it out on the side of your ice bear stone and see if the stone wears too fast).

Hand America has Black Diamond stropping compound (cubic boron nitride). Diamond will work just fine but you'll probably have to use diamond paste on a cast iron plate or strop if you want to get into the really fine stuff. Stones for sharpening tungsten carbide tools would probably work too. King makes a 1,000 grit waterstone using diamond in a ceramic matrix, but it is a bit expensive. Your best bet is diamond eze-laps. These should work too http://www.titantoolsupply.com/tbhh.html
 
yuzuha said:
Your best bet is diamond eze-laps.
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I got one today, but 1200 - super fine more corse then Sharpmaker Medium stones. I am wondering why Med works? Same aluminium Oxide as on Fine, and I able to make blade shaving sharp.

Also why it is not a problem to sharpen S30V?

Please, note also that it is not about generic sharpness - I have that sharpness testing "machine" and measuring sharpness on it. After Medium - result for S90V and S30V are the same - about 90pt. Then Final stage Fine Rods bring S30V to 65pt but S90V to 120pt. However Ultra Fine Rods brings S30V back to about 100pt.

However 90pt - shaving sharp. It is just acts different then S30V and I it is OK. I saw that bulat(wootz) for example can not be sharpen to same points as other steel, but Fine did not dull it.

Thanks, Vassili.
 
yuzuha said:
If the abrasive is harder than the carbides, it will sharpen the carbides too. If not, then they will just scratch the stone and fall out when the stone wears away the metal that is holding them. Vanadium carbide is harder than chromium oxide and most types of aluminum oxide (maybe a pure sintered ruby stone would be harder, but I can't find hardness values on the same scale to compare). Cubic boron carbide, nitride and diamond are harder than Vanadium carbide so things made from them will work. Some types of silcon carbide are harder and some are softer so you'd have to try SiC stones.

Most of the finer waterstones are made with aluminum or chromium oxide. You might find some with fine silicon carbide that will work. (try it out on the side of your ice bear stone and see if the stone wears too fast).
Click to expand...
A more common name for aluminum oxide is sapphire. Or corundum. Ruby is also a corundum, but with chromium (which makes it red). Both sapphires and rubies are 9 on the Mohs hardness scale (diamonds of course being 10). I don't know how this translates in to Rc though, or how they work with the carbides in steels.

It sounds like diamonds might be the only viable option for high-hardness S90V.
 
Vandium Carbide is roughly 2800 on a Vickers hardness scale. Aluminum oxide is 2400. The Vickers scale is a diamond micro-hardness scale. PM steels have carbides that are 2-4 microns in size. S90V has a high volume of carbide, roughly 20%. Of that nearly half is vanadium carbide. S30V has roughly 15% total carbide with about 5% of that being vanadium carbide. An abrasive bigger than 4 micron will essentially abrade the matrix of the steel and all materials will have the same essential "sharpness". When you have an abrasive harder than vanadium carbide and can get it below 4 micron in size it will cut the carbide and enhance the "sharpness". I have seen this first hand at a knife show when Bob Lum and Wayne Goddard compared high vanadium grades to non-vanadium grades. On conventional stones the sharpness was similar. When the high vanadium grades were sharpened on Bob Lum's diamond stones the sharpness of the high vanadium grades more than doubled the others. The key to utilizing the high vanadium carbide grades lies strictly in the abrasive used to sharpen them. Diamonds are the easiest way to do this.
 
nozh2002 said:
After Medium - result for S90V and S30V are the same - about 90pt. Then Final stage Fine Rods bring S30V to 65pt but S90V to 120pt. However Ultra Fine Rods brings S30V back to about 100pt.
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So even S30V is degraded on the UF stones?

I am wondering why Med works?
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If the abrasive size if larger than the steel's grain and carbides all steels will behave the same because the teeth are all the same, it is only when you go to really fine finishes, so that the teeth are smaller than the carbides and grain of the steel that they will be an influence on sharpness.

Satrang said:
When the high vanadium grades were sharpened on Bob Lum's diamond stones the sharpness of the high vanadium grades more than doubled the others.
Click to expand...
Which steels were being compared and how was the sharpness being determined?

-Cliff
 
The tests for sharpness were done using 154CM, 440C, S30V, CPM 10V and maybe one other, but it escapes me. The S30V, 154CM, and CPM 10V knives were nearly identical since they were made by Phil Wilson and nearly the same pattern. Goddard wanted them specifically for that reason. Wayne did the sharpening on all knives with both the conventional and diamond stones to keep that relatively consistent. The cuts were rope cuts. Overall, it was the most consistent test of sharpness that I have seen since many of the variables were kept as constant as possible.
 
Thanks for the info, how was the sharpness measured, what did the "more than doubled" refer to, was it thicker rope, less blade length or less force used?

-Cliff
 
FYI - This is my test "equipment".

Random-44.jpg


Thanks, Vassili.

P.S. I am really proud that I was able to catch this vanadium carbid vs. aluminium oxide situation with this equipment.
 
1 micron is 14000 grit - way more then finest 1200 diamond stone grit. even more then 2000 grip wet sandpaper (silicon carbide).

What is Spyderco stones grit? To really be in this situation Medium suppose to be about 8000 and Fine about 14000. If it is not than it may be I am doing something wrong.

For example I newer strop it on leather - it works fine for me so far. As I remember Spyderco sad it is not nessesary. May be this steel able to make wier even on Spyderco rods?

Thanks, Vassili.
 
"...medium and fine ceramics, they are estimated to be at 12.5 +/- 1.0 and 6.5 +/- 1.0 micron respectively..."

Also I have great link from daverave999's answer on my question on Spyderco forum http://208.63.68.209/SharpenGuide.htm#Grit

ExtraFine is 3 microns
Fine is 6 microns
Medium is 15 microns

This means that Fine and even ExtraFine should sharpen 2 micron carbides just fine!

It may be several conclusion on why it is happen this way:
1. Vanadium Carbides are bigger then 2 microns - bigger then 6 and less then 15.
2. Just moving blade holding it vertically not enough to utilyze what quality stones are offering. I am doing something wrong. Like - wire is developed and need to be taking off by stroping on leather?
3. May be someting wrongwith stones itself - they are like 1 year old

Wire on the edge - why it developes? It is usually not a case for Sharpmaker - at least I never do anithing special, and may be for this steel it is happen because of its properties?

Thanks, Vassili.
 
The teeth would have to be much larger than the carbides if the carbides are not cut by the abrasives. Just consider a tooth with a piece of carbide in it, unless there is a signifiant amount of steel all around it, it will quickly break out.

-Cliff
 
Cliff Stamp said:
The teeth would have to be much larger than the carbides if the carbides are not cut by the abrasives. Just consider a tooth with a piece of carbide in it, unless there is a signifiant amount of steel all around it, it will quickly break out.

-Cliff
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Please, explain bit more - I think I am geting picture but not entierly yet. You mean that vanadium carbide hardness take effect even if abrasive grain if bigger, because it is not just carbides makes surface but steel teeth with carbides on it and density of carbides are also inportant?

This mean that to successfully sharpen it I need some abrazive on 6 microns, 3 microns.

BTW, It is interestin that my reading is same as yours, even I saw it just now. 60-90-140 (after Spyderco diamonds).

I actually notice degradation or no effect on Ultra Fine for almost all steels.

Thanks, Vassili.
 
nozh2002 said:
This mean that to successfully sharpen it I need some abrazive on 6 microns, 3 microns.
Click to expand...

I sometimes strop on leather loaded with a 1 micron diamond paste when I want to have a highly polished edge. These pastes are available in 0.5 microns, 1 micron, 5 micron, 7 micron, 10 micron and so on.

Hans
 
Habeas Corpus said:
I sometimes strop on leather loaded with a 1 micron diamond paste when I want to have a highly polished edge. These pastes are available in 0.5 microns, 1 micron, 5 micron, 7 micron, 10 micron and so on.

Hans
Click to expand...

Please, tell a bit more about this. I saw this diamond paste and spray (probably better) in juwelry store (store for juwelers) but it is expensive. How many of this thing is needed and how to use it properly. And which is better to use after 15 micron Medium Spyderco stones or should I use it in sequense?

Thanks, Vassili
 
nozh2002 said:
Please, tell a bit more about this. I saw this diamond paste and spray (probably better) in juwelry store (store for juwelers) but it is expensive. How many of this thing is needed and how to use it properly. And which is better to use after 15 micron Medium Spyderco stones or should I use it in sequense?
Click to expand...

I've never seen the spray, so I can't comment on that. I use oil-based diamond pastes I bought on Ebay. Dissolve in alcohol or any other suitable solvent and use a fine paintbrush to put a thin coating on your stropping leather. Allow for an hour or so to let it dry.

I got 5 grams each of the 1 micron, 10 micron and 20 micron paste.The 20 micron is quite useful to touch up the edge of a knife from time to time. I tend to use the 10 micron most for stropping my knives. Cost ... well, over here 5 grams usually sell for something like 10 dollars on Ebay. That's not that expensive considering 5 grams will probably last for several years. I normally only put a new coating on my strops after half a year or so.

Hans
 
nozh2002 said:
P.. carbide hardness take effect even if abrasive grain if bigger, because it is not just carbides makes surface but steel teeth with carbides on it and density of carbides are also inportant?
Click to expand...
Yes, if the abrasive can't cut the carbides, then the micro-teeth would need to be singificantly bigger than the carbides for a clean edge to form, otherwise it would just be ragged with tear outs.

-Cliff
 
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