New testing session.

Vassili, I have some steels I plan to compare for edge retention (I plan to do ZDP189 and 8Cr13MoV first) but in general I find it very time consuming to do. How quickly does manilla rope dull an edge compared to cardboard?
 
Eventually, I will test all steels in my collection, which is pretty good. I may not have YXR7 and CPM S125V, but otherwise I have a lot of steels - even exotic bulat/wootz made by Ivan Kirpichev.

Currently I am waiting for CPM S110V - Shallot, but USPS flying with it like an eagle somewhere second week already...

Thanks, Vassili.
 
Nozh2002 - Perhaps edge realignment or carbide loss could explain it, but you could test for this by doing more frequent measurements on those steels that seem to vary significantly from one set of measurements to the next. If this is in fact what's happening then you'd catch it as it occurs. Yes, much more work. If sharpening shows a predictable trend then that would tend to eliminate the thread variable, but not the manilla rope variable.

Even so, what I said before still stands. Comparable blade performance and relative ranking would change from one cutting and measurement session to the next. However, the significant differences between Dozier D2 and say the Benchmade D2 are so obvious that any error in your test methodology can be disregarded. It is only when two steels are very close in performance that things might change around within the variables.
 
Vivi said:
Vassili, I have some steels I plan to compare for edge retention (I plan to do ZDP189 and 8Cr13MoV first) but in general I find it very time consuming to do. How quickly does manilla rope dull an edge compared to cardboard?
Click to expand...

I never try cardboard. Rope allows me to focus more or less even load on certain part of the blade and does not resist to cutting too much.

I strongly believe that most what dull the edge is wooden base if someone cutting on wooden base. This is why I made special thing to cut only rope and end cut in the air.

I manage to do one test in full day - like Sunday, or two evenings.

But my skin already adjusted to thread - became rough and thick in right places. My arms get used to this operation, so it may take some time and some pain to get to it.

Most important is to avoid damage to arm - I use very tight gloves when I cut which prevent stretching, Also I limit cuts to 200 - blades do not get completely dool and may be used for a whyle after this, but it probably cover what blade can get during normal casual use. And prevent injuries for tester. I had to wait quite a bit after my previous testing while my hand got fixed.

Thanks, Vassili.
 
Steelhed said:
Nozh2002 - Perhaps edge realignment or carbide loss could explain it, but you could test for this by doing more frequent measurements on those steels that seem to vary significantly from one set of measurements to the next. If this is in fact what's happening then you'd catch it as it occurs. Yes, much more work. If sharpening shows a predictable trend then that would tend to eliminate the thread variable, but not the manilla rope variable.

Even so, what I said before still stands. Comparable blade performance and relative ranking would change from one cutting and measurement session to the next. However, the significant differences between Dozier D2 and say the Benchmade D2 are so obvious that any error in your test methodology can be disregarded. It is only when two steels are very close in performance that things might change around within the variables.
Click to expand...

Yes of course! This list as I sad is pretty rough. This is why I honestly provide all results first, but it is much hard to consume, then simple ranking.

On the full array of results however you may see what dominates and what is most likely random variation which jump out of line.

However volatility of results also may be meaningful as well - natural property of certain steel and may indicate poor HT or something.

Thanks, Vassili.

P.S. I showed this results to my other Russian friends who have more specialization in probability theory and experimental physics - those results look pretty much same as any other test results they worked before. This is normal scientific process and volatility if natural for it.
 
Excellent work!

By the way, It would be very nice to see the results for old good steels in comparison with today's high-tec (I mean 154CM, 440C, ATS-34, VG10...)

I know, Vassili, that you owns the Buck-Strider made from ATS34, treated by Paul Bos...
 
Bad Dog said:
Who uses dD2 for blades? Pretty awesome results.
Click to expand...

This is regular D2 on Dozier knife. Dozier very well known knifemaker - king of D2, his heat treatment is legendary and you may see why. I call it dD2 meaning that this is Dozier D2.

Thanks, Vassili.
 
About why I think it tests edge retention and does not depend on size, grind an geometry...

...I sharpen blades under same angle to same sharpness level - hair whittling sharpness. And then after cutting manila rope certain times measure sharpness o very edge by thin thread. Thread is affected by very edge because it it very thin - so only angle of the edge really matter, blade grind, blade length does not matter, as well as edge thickness.

I eliminates all knife features but edge angle, which I sharpen same for all knives. So this is why I think it is only steel condition (composition purity and HT) - edge retention affect results.

Manila rope consists from many small threads which also need small part of the edge to by cut out and fall away (I cut 1/4"-1/3" from the end - cutten pieces of fiber jumps away)...

Thanks, Vassili.
 
nozh2002 - I understand the edge testing methodology, and I think you have isolated edge sharpness pretty well with it, but what about blade grind type?

All of my Doziers are hollow ground, and I would bet the one you're using is also hollow ground. Are any other knives in your test group hollow ground? If so which ones?

It could be that a hollow grind simply works better when cutting manilla rope compared to flat grinds, convex grinds and saber grinds. A hollow grind may slip through the rope easier putting less stress on the edge which results in higher retained sharpness. On the other end a convex grind might require a bit more pressure to work through the rope which could induce greater wear on the edge.

It would be interesting to test Dozier's D2 in a flat or convex grind to see if you get different results.
 
Steelhed said:
nozh2002 - I understand the edge testing methodology, and I think you have isolated edge sharpness pretty well with it, but what about blade grind type?

All of my Doziers are hollow ground, and I would bet the one you're using is also hollow ground. Are any other knives in your test group hollow ground? If so which ones?

It could be that a hollow grind simply works better when cutting manilla rope compared to flat grinds, convex grinds and saber grinds. A hollow grind may slip through the rope easier putting less stress on the edge which results in higher retained sharpness. On the other end a convex grind might require a bit more pressure to work through the rope which could induce greater wear on the edge.

It would be interesting to test Dozier's D2 in a flat or convex grind to see if you get different results.
Click to expand...

Yes Hollow Grind and thinner edge works better - I need less force to apply to cut rope, even it formed with fibers, but still some friction between edge and even blade and remaining part of the rope body exists. But I am not measuring this force as Phill Willson and other.

I let it affect very edge and then measure what force needed to cut thread. Thread is very thin and it cuts by only fraction of very edge itself. There is not friction between thread body and blade - there is no too much penetration into thread body, this is why use thread. Putting force needed to cut rope out of equasion I eliminate dependency of results on grind etc.

So I am measuring how the very edge affected not how pleasant rope cut is. And yes force needed to do cut rope vary from knoife to knife even edge produces same result on thread.

Thanks, Vassili.
 
wow, that Swamp Rat looks so out of place, considering the advertised hardnesses and alloy content of the steels immediately in front of and behind it.
 
nozh2002 - It is that very pressure while cutting that I'm talking about. If greater cutting pressure results in greater edge wear then blade geometry could be having as great or greater influence on edge retention than steel composition. The only way to know for sure would be to eliminate blade geometry as a variable by comparing only flat grinds or hollow grinds, etc.
 
Steelhed said:
nozh2002 - It is that very pressure while cutting that I'm talking about. If greater cutting pressure results in greater edge wear then blade geometry could be having as great or greater influence on edge retention than steel composition. The only way to know for sure would be to eliminate blade geometry as a variable by comparing only flat grinds or hollow grinds, etc.
Click to expand...

This greater pressure spreded on bigger edge surface, the very edge has same pressure - one what needed to do cut, actually. It is only hand of the tester affected.

However you may prove it - test it by doing same test I do for same steel with same heat treatment and different grid. If results will be different - than you are correct.

Thanks, Vassili.
 
nozh2002 - Ah, I'm a manager. I don't do any actual work. I get others to do that for me. ;)

I was thinking about this. I could never match your testing methodology exactly so I will have to come up with something of my own. I have some ideas about how I would change it around a little. For one thing I would use 3 inch hawser instead of small diameter manilla rope. Are you doing push cuts only, or do you use a slicing or toggling motion of any kind? I won't be able to set anything up until I get back home in January. Then I'll see what I can do. Meantime, you might try it too. Thanks
 
Steelhed said:
nozh2002 - Ah, I'm a manager. I don't do any actual work. I get others to do that for me. ;)

I was thinking about this. I could never match your testing methodology exactly so I will have to come up with something of my own. I have some ideas about how I would change it around a little. For one thing I would use 3 inch hawser instead of small diameter manilla rope. Are you doing push cuts only, or do you use a slicing or toggling motion of any kind? I won't be able to set anything up until I get back home in January. Then I'll see what I can do. Meantime, you might try it too. Thanks
Click to expand...

This is just excellent! More independent result - better and different procedure may highlight different qualities of blades.

Be careful with media you are choosing to cut - this is not casual cutting - I do 200 cuts each blade 3640 total up ti this time. Think if your arm can handle it without injury.

I cut it notrmal way - push and slice combination - slightly moving it forward, but not moving away from testing point. It affect about 1" wide area on the blade.

When I cutting thread - no moution alloved and no waiting, I allow about 2-3 sec on each mark on the scale and then proceed to next. This is important. Sliding edge you may get way better result because it slide on all dull part to the sharp and you will have sharpness only on sharpest spots - this is what happen I suspect with my previous testing year ago. Also If you wait long enogh it may cut thread with very small pressure. So Again - no endless wait, blade should move down with same speed, may be step by step and no sliding to the sharp spots.

Thanks, Vassili.
 
Look at Buck 420HC results! Pretty impressive. I was very impressed first time I did testing with Teiwan 420HC on Cold Steel ODA. Buck is doing it even better!

Finally I got CPM S110V Shallot and going to resharpen it - straight edge and then test.

Initial sharpness out of the box was 5.5 oz, no whittling hair.

Thanks, Vassili.
 
Shallot resharpened and I am testing it right now. Interesting - I was not able to whittle hair. I resharpen it and still was not able to whittle hair. May be it is nature of this high on vanadium carbides steel? It has same 2oz. but not whittling hair. I was bit surprised that removing S-curve was not really too hard, as I expected from this supersteel.

Well, we'll see how tests will go.

First cut require noticible more pressure then othe knives with same sharpness - may be because of hig abrasive sides of the edge? Like it sand paper because of all this carbides?

Thanks, Vassili.

P.S. I think my trouble with cutting rope is not about steel, but because of uncomfortable for this kind of cutting handle - too thin, too metal... I have less problem with glove.
 
Last edited:
Did some research on CPM S110V:

http://www.crucibleservice.com/datash/Datasheet CPM S110V Rev 1.pdf
http://en.wikipedia.org/wiki/Niobium

From regular CPM steels it differs by huge amount of Nb (Niobium - 3.5% when usual contents of this alloy in steel 0.1%) and Co (Cobalt).

Quote from CDS:

"CPM S110V features the same high vanadium content as CPM S90V, plus the added contribution of 3.5% niobium, resulting in 25% greater volume of wearresistant carbides, including 50% more of the wear resistant MC type."

I may suspect that it does have quite an abrasive property. So this is sandpaper-like steel.

Typical Application Hardness: 58/61 HRC - this is why I did not have too much problem reprofiling blade.

I am wondering if Niobium Carbides as well as Cobalt Carbides have greater hardness then Chromium Oxides in Green rouge and so I was not able to make it whittling hair? I should try 0.3 microns diamond powder.

All this make me understand why it was bit behind ZDP at the beginning but then stays better. I guess it may stay this good way after 200 cuts...

Thanks, Vassili.
 
David Martin said:
Its interesting Dozier knives stayes on top even though he does NOT use a cryogenic soak in his heat treating.!! DM
Click to expand...

I sharpened both of my Doziers just recently and I see bulat/wootz pattern on the sides of the blade in light reflecting from surface. I am wondering if he on purpose or accidently fount HT which make bulat out of D2. It has same composition as bulat and repetitive thermicycling beyond vanadium carbide dissolving level may create carbides micro structures inside blade body. However in theory this need to be forged to benefit all those carbide threads inside. But from bulat I have did not really perform as good as Dozier.

I am wondering if Bob Dozier thermo-cycle and forge his blades?
I am wondering did somebody try to etch Dozier blades to see bulat pattern?

Thanks, Vassili.
 
Last edited:
You must log in or register to reply here.
Back
Top