Sods : Uddo, Temperance, Surefire, AK-47

I had intended this to be a different sort of experiment and I didn't get to examine what I wanted to because the effects were more random than I thought. In general soil usually isn't that random but this lawn was heavy infill and thus it was contaminated by all sorts of odd objects :

-chisels
-glass
-nails

and even the rock content was very uneven and so I didn't get the sample size I wanted to. Still though there were some interesting conclusions, and what I am going to talk about here is only the first part as I am only about half way done.

Each knife was used to cut three sections of sod, so a total of 12 were cut (for walk-way stones), they were all sharpened on the fine section of a cheap benchstone. The second part repeats this and uses the coarse side to sharpen.

Uddo Puukko :



-reground to FF, edge is less than 0.005"/10 dps
-total passes to resharpen (fine benchstone), was 660 (117) for three sections cut




-little damage, no chipping, just flattening, wear



That is the edge under 50X magnification, again just really flat/worn.


-not a great functional choice
-too small, especially in the grip
-little prying ability, blade is too narrow and would break the sod

The chisel was actually under the sod, I later cleaned it up and will post about it. It is perfectly fine and will make a nice shop chisel for a friend.

Surefire Delta :



-edge is regound, 0.018"/11-12 dps



-damage was visible
-lots of chipping and rolling
-consistent with wood and cardboard work
-seemed to improve a little with each sharpening

-600 (43) pps to resharpen on the fine benchstone (total of three runs)

-very functional for the work
-wide blade, rigid for prying
-nice belly for skinning off the sods
-handle is decent, a bit uncomfortable as it is all open, but well rounded

Temperance 2 :



-edge is 0.020"/13-14 dps



-1350 (43) pps to regrind the edge (total of all three sections)



-the edge took little damage, just flattening and wear

-it was however not a practical choice
-the handle is too heavy and very slick
-the blade is too long
-not enough belly
-the tip is too narrow and will easily break the sods in prying

AK-47 :



-edge is 0.022"/10-11 dps

-600 (115) pps to resharpen (all three runs)

-edge just flattens, no significant damage

-easily the most functional blade
-handle is comfortable (has had a lot of work done on it)
-blade is wide and very rigid for excellent prying



-large belly works very well in skinning off the sod

I was curious if there would be a significant difference in ease of sharpening considering the difference in the steels, but only the Temperance was significantly different :



Note however the Vector is clearly defective, it has the same ease of damage no matter what is cut - nice knife though if you ignore the spastic steel.

The Cold Steel easily is the knife to use, the others are not even competitive with it aside from the Vector which is still behind in the edge damage greatly and the open handle will get to you after awhile.

I have all this being repeated with the other side of the stone and it will be interesting to see if the Temperance still shows the large difference in ease of grinding and if the Surefire eventually gets to decent steel.

Excellent test Cliff! I'd really like to see more sod tests in the future.


Chumgeyser on Youtube
E-nep throwing Brotherhood. Charter Member

Yeah this is an interesting test. And as a follow up you could try sharpening them with the 24 grit nubatama stone, I think you would see some interesting results.

We use Olfa cutters on farmed sod... they make about 3 cuts, then ripping starts, then pieces of Olfa are everywhere. I wear safety glasses.

Our "special" serrated sod knives are way too short and failed to make any push cuts... they rip about 10 cuts then become resistance training devices.

I am afraid to use my personal knives for this task... my jungle knife did not do very well on rockwool.

What stone did you use to resharpen? Cheap one huh? That is a lot of passes to do.



Edited 1 time(s). Last edit at 07/06/2013 07:26PM by Old Spice.

Quote
Mark a
And as a follow up you could try sharpening them with the 24 grit nubatama stone, I think you would see some interesting results.

That stone would actually do more damage to the edge than the cutting, it is really coarse. It can be used to sharpen but you have to use a lot of water and press fairly light. I normally use that just to grind edges flat, reshape points, adjust the belly, work old machetes and similar.

Quote
Chum
I'd really like to see more sod tests in the future.

I was just informed the walk-way is to be twice as wide as originally planned so I have to repeat it all again once I get the next run done. That will likely be next week. I might add a few more knives to the mix, the M2 Benchmade is an interesting one.

Quote
Old Spice
What stone did you use to resharpen? Cheap one huh? That is a lot of passes to do.

That is the combined total for all three cuts, so for most of the knives it was 200 pps per sharpening, and this is to restore all damage and get the edge back to shaving. Between 50-75% of the passes were on the first inch of the blade under the tip as that area gets heavily impacted when it hits the rock. With a decent stone it would be cut in half, drop the grit down and you could easily cut it in half.

The other side of that stone cuts even worse, I am expecting the pps to rise dramatically and be 50-100% greater.

Quote
wnease

I am afraid to use my personal knives for this task.

Ha, I was hoping I would get the Modulator on Friday.



Edited 1 time(s). Last edit at 07/06/2013 08:30PM by CliffStamp.

M4 is interesting, and I've very much like to see how it performs in this type of test. I've read discussion Cliff and whatfor5 have had on it, as well as individual assessment of the steel. Cliff, am I correct in saying that M4 appears to perform better than its chemistry would suggest? I believe that was what whatfor5 was suggesting.

One more thing... Aus8 gets a lot of flak on the internets for being a shitty steel. The common complaint is that it doesn't hold an edge very well. Of course people aren't basing this on anything except what they have heard. Aus8 seems like a good compromise steel to me, and the more I read Cliff's testing data the more I believe that to be true. Good edge holding, good stain resistance, good toughness, good edge stability. It may not be the best at any of those markers but it is good at all of them.

Perhaps CS knew what they were doing when they chose Aus8


Chumgeyser on Youtube
E-nep throwing Brotherhood. Charter Member

Give it some time Chum, I don't think it will be long before Cliff sees a major failure with the CS Aus8.

Quote
Old Spice
Give it some time Chum, I don't think it will be long before Cliff sees a major failure with the CS Aus8.

I know you have had issues, or at least one major issue, with the Rajah but perhaps you just got a lemon.

A lot of major cutlery companies use Aus8. In part that is probably due to cost. However, given that Cold Steel, SOG and others have used Aus8 for a long time, would you say it has a track record of failure? It is hard to say, but this forum in particular is a watchdog of knife failures. Given the quantity of Aus8 knives in the market it has seemed to hold up well to public scrutiny, at least as far as failures go.


Chumgeyser on Youtube
E-nep throwing Brotherhood. Charter Member

I have seen enough failures to be skeptical of CS Aus8 under hard use.

Quote
Old Spice
I have seen enough failures to be skeptical of CS Aus8 under hard use.

You've seen a lot of failures from 1095 as well haven't you? Is it the steel or the heat treat that is the issue?


Chumgeyser on Youtube
E-nep throwing Brotherhood. Charter Member

I'm not arguing that Aus8 is a bad steel(its not), I'm arguing that Cliffs AK will fail in a not so suprising manner.

Quote
Chum
...am I correct in saying that M4 appears to perform better than its chemistry would suggest?

No, you can't defy the laws of physics.

Myself and a number of others were advocating HSS to various knifemakers on the forums in the late 1990's. Benchmade started using M2 and openly admitted that it performed better than ATS-34 in all areas aside from corrosion, however they would not switch to using it because of the marketing cost necessary to inform the public.

In regards to M4, it is a high wear HSS, specifically it is M2 with a higher vanadium content (which gives the increased wear) and a very small increase in carbon content (hence the slightly increased hardness at similar cycles - 1/2 HRC points). Of course directly corresponding to this is the decrease in toughness.

For more information : [www.erasteel.com]

In general the reason that there is so much variation in what is reported is because of the massive difference in how it is being used. In the BladeSports competitions it gets severely underhardened because if it doesn't it has far too high of a tendency to explode (gross fracture) and even with the underhardening it still does not last very long before it is damaged so it is a very poor choice for an impact tool.

This of course is not unexpected as it is a high hardness, high wear HSS steel, using it for impact tools is like using L6 for salt water fillet blades. It should be immediately obvious that you are going to have problems with corrosion.

The other thing is that HSS are actually cutting steels and thus there is tremendous amounts of research on them to make them perform better in cutting tools, steels like ATS-34 are not hence the lack of study on it. It is trivial to find data on HSS because of this, for example :

Have you ever wondered why HSS benefit so much from undersoaking : [www.kau.se] .

Note the clear description how a larger primary carbide with larger gaps between them leads to an increase in fracture toughness because of the necessary plastic deformation needed to drive the cracks through these distances through the carbides.

Were you ever interested in the details comparing convention, spray form and PM HSS if the steel was exactly the same just formed in different ways : [www.kau.se] .

Try to find this data on ATS-34 vs PM 154CM.

Quote

Aus8 gets a lot of flak on the internets for being a shitty steel.

It gets used in cheap knives and thus gets cheap processing. It is the same class of steel as MBS-26, 19C27, CTS-BD1 . You are looking at a steel which has a maximum hardness of 62-64 HRC, a far higher wear resistance than O1, AEB-L and still will respond well to cheaper stones.

If you want a different perspective on it, try looking at some of the older Benchmades or the Spyderco MBS-26 knives.

Quote
CliffStamp

Quote
Chum
...am I correct in saying that M4 appears to perform better than its chemistry would suggest?

No, you can't defy the laws of physics.

I was suggesting that while we know the chemical makeup of M4, perhaps it wasn't performing as one would expect based purely on that chemical makeup, not that it was defying the laws of physics

Just because we know what something it made of that doesn't mean we know everything about it, how it will behave in certain environments, how it will interact when tested etc.


Chumgeyser on Youtube
E-nep throwing Brotherhood. Charter Member

HSS is a curious steel because some parts of it are a little contradictory, but it isn't in general surprising to see it perform as it does. In general :

a) HSS has very low chromium carbide while many high wear steels have a lot. Chromium carbide is not only softer than the HSS carbides it tends to be much larger and thus in very thin edges it breaks out and thus the edge retention and especially edge durability isn't nearly as high as the gross wear resistance or impact toughness would imply.

b) HSS has a very fine aus-grain which increases strength and toughness

c) HSS will have very low retained austenite and non-martensite phases due to the ability of high tempers to transform the steel to martensite. This is much more effective (in general) than even low temperature quenching

d) HSS in general are fairly flexible in response and it is possible to get a fairly wide range of properties through altering the hardening hence the use in Bladesports and in folders. This however is abused by some makers/manufacturers and even users who imply the toughness of the BladeSports choppers is in the small folders - this is not true, they are hardened very differently.

Now if you read all of this you would wonder why the hell would you use anything other than HSS. Well there are a few reasons :

a) HSS are fairly expensive compared to cold work steels

b) It is only very recently that makers would even reach the temperatures for HSS soaking. Even a short time ago makers like Phil Wilson could not because of low temperature restrictions of the foil and the furnace itself. Now there is high temp foil, positive pressure furnaces, etc. .

c) Low corrosion resistance.

d) Some makers like the very coarse edges of low grit stones and if you are using them then you lose most of the benefits of HSS and you might as well use the coarse chromium based steels (D2, ATS-34, etc.)

e) Not to sound elitist, but you need a decent level of sharpening skills to see any difference. If you struggle getting a knife to slice a piece of photocopy paper then HSS is wasted.

So if you can get a good edge and don't mind some maintenance then M4 is the ultimate knife steel?

I have been very happy with my gayle Bradley. I am amazed at the length of time between sharpenings. I am tempted to put it in my shaving testing but, it may take years to dull it enough to have to resharpen it.



Edited 1 time(s). Last edit at 07/08/2013 03:01PM by Mark a.

I would not go that far, it is simply a decent HSS. The main reason it compares well is because it gets compared to steels such as ATS-34 it would not for example dominate steels like Super Blue. Roman has maintained that the HSS are inferior to the cold work tungsten steels however I have not see the data to support that claim directly but you also have to consider Roman's perspective on :

-very high sharpness
-extreme quality of heat treatment

The cold work steels in general are not as forgiving as the HSS. This doesn't concern Roman as he does his own hardening and can put in the effort, but when you have people using 5160 (Buck and Bark River) and it is more brittle than D2 then this is a real practical concern.

Are there temperature standards for HSS (hot) and cold work steel in use? I have read that HSS can get bright red (?) in use and that room temperature could mean as hot as 500* F. So, the cold in cold work could be only relative in use (perhaps, below the tempering temp?)

Yes, HSS generally refers to red hardness which is the ability to sustain hardness even at such elevated temperatures.

Yes, even cold work steels will take 500F without significant loss of hardness, in fact that is very close to the common hardening temperatures (350-450 F).

I did some work with the 710-Axis :



+



It did almost nothing to the blade. Here is 5X magnification :



Here is 50X :



For reference this is the bottom section I was tooling around on fibreglass insulation :



Now before anyone gets too excited this one has a much higher angle than the other knives :

-edge is 0.019" thick, 18.5 (5) dps

And I am getting to be a ninja-sod cutter so the knives are doing less work. There is a sweet spot in skinning off sods, you need to cut deep enough to get to the weak point of the roots. If you cut too deep the sods are very heavy and difficult to pull up and move around, if you cut too shallow then they can rip and you do a lot of work to cut.



-200 pps, to restore

I would want to do more (specifically 7 runs) before making a judgment but it is easy to see how people have such dramatic opinions on steels because this run was very different than the others and thus if someone just did a 1:1 comparison this knife would look insanely higher in performance.

It is easily the best sod cutter out of all of them aside from the fact it isn't great to pry with because the blade is narrow, however as my sod-skinning skills increase I am finding that I am doing this less and less anyway.

After a few more runs the performance evened out as expected :



+



Note the larger rocks and glass, again the damage is really random. It takes awhile to average out. A few edge shots of different runs :



+



+



Over all it behaved much like the Temperance 2 in regards to speed of sharpening, again basically showing that high carbide steels don't tend to help in really "hard use" because the edge will get damaged and just takes longer to regrind.

It is really nice to use for it though, aside from the fact that the pivot screw constantly backs out and if you tighen it completely to stop it the knife binds completely. It looks like it needs thread locker.

As I still have some left :



-S125V
-13/14 dps

The interesting thing is that while the edge does chip :



it also rolls :



Now this edge had an extremely harsh acid soak so I am not going to place much on this until I sharpen it a bunch of times. This is one of the reasons I wanted to use this knife for this work.



It actually grinds fairly easy, considering the steel :

-375 pps

and takes a decent edge :



It can easily shave, but that edge is really coarse, it is like shaving with a saw. It takes hair off easily but it isn't comfortable.

For years I've avoided recurves after a bad experience with one of the original 710's in the late 90's. I may have to look at it again, as I keep my work knives in the 15-20 dps range for scraping and such.

What was the problem with your 710?

---------------------------------------------------------------------
Artificial intelligence is no match for natural stupidity.
zujostix (Youtube)

This one has a much less pronounced recurve now because the wear was mainly in that area and I didn't both to keep grinding out the hollow section to match the amount of steel removed from the outsweep in sharpening.

In reflection the upwards sweep next to the handle does very little due to its curvature, you have to be doing some fairly odd cuts to make that have a positive effect. That would be much better in general if it was flat in that area.

After more work with the 710-Axis in the above I am getting less impressed with it because the pivot needs thread locker at a very particular setting to allow the blade to rotate freely and keep the lock secure.

If it is over tightened then the blade binds, if it is too loose then the lock is instable.

Do you think that is the problem that all 710 would have, that all Axis lock knives would have or that it could be integral in the McHenry-Williams designs such as the 707?

---------------------------------------------------------------------
Artificial intelligence is no match for natural stupidity.
zujostix (Youtube)

No idea : [benchmadeforum.com] .

That link to the BM forum is me asking if this is the expected behavior. The response, while scattered, is one of the least shill based responses I have seen. If the entire forum is like that then it is a valuable place to discuss the knives.

I just confirmed that the RSK doesn't act like this at all. I have to get it back from my brother to try to figure out what is happening between it and the 710 that is so different.

Cliff, how do you think the Piranta would perform on the sod using the large, stiffer, 60A blades? I know you don't have those blades but best guess.


Chumgeyser on Youtube
E-nep throwing Brotherhood. Charter Member

There would be a significant chance of them breaking how it is cut. The edge would likely get significantly dented/rolled, assuming you had the control not to break it.