Category Archives: Advice

STEEL K390 BÖHLER’S MICROCLEAN – UNCANNY BLADE MATERIAL.

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I have seen a video where someone is stabbing concrete with its Spyderco Police 4 to show how K390 is strong ! The blade of that famous knife is thin and this thinness is here for a purpose: Sal Glesser has decided to use the Police 4 plateforme according to his own desire but toughness and impact resistance may have weighed in on the decision. For once the Police is not especially aimed at the LEO but those ELU who use their thin knives hard !

“We make quite a few designs for the Law Enforcement market at this time, so the design for Police use is necessarily the case anymore, like it was in 1984. I designed the Police 4 to include what I would like in a knife, more than what a LEO might like. It’s still a kissing cousin, and large for most people. I widened the blade, enlarged the hole and selected a steel that I like to use. The design’s success in the marketplace is unknown at this time. But I get to have one. ” Sal Glesser.

K390 is not stainless. It’s a cold work tool steel which uses Bohler proprietary Microclean technology.  K390 has close to the same edge holding as A11 but is much tougher. Bohler’s third generation particle metallurgy contributes to the toughness of the steel.This steel will be hard to grind, finish and sharpen. Once it is sharp it will stay sharp for a long long long time. It’s CPM M4 on steroids which means K390 has more strength, durability, stability and wear resistance than M4 ! And I do love CPM M4.

Here is a video which confronts CPM M4 and K390:
https://youtu.be/TI53ziibeiQ

From Bohler’s commercial:

“K390 is quite simply the powder metallurgical cold work tool steel with the best properties for cold work applications available from BÖHLER at the moment. K390 MICROCLEAN was developed to meet the demanding wear resistance and compressive strength requirements of cutting, blanking and punching applications, for cold forming applications and for parts which are subjected to abrasive wear in plastics processing. Tool life can be increased by several hundred percent due to the outstanding wear resistance, high compressive strength and good toughness of BÖHLER K390 MICROCLEAN. These material properties enable our customers to make their production processes more efficient and consequently to reduce the price per part produced. Too hard to be machinable? Quite the opposite. The task of the tool steel manufacturer is to produce a steel which is, on the one hand, easy and economic to machine (with a hardness of around 280HB) and simple and unproblematic to heat treat, but which, on the other hand, has a very high hardness (up to 64HRc) and optimum performance in use. The secret lies in the powder metallurgy process. A very fine, homogeneous microstructure guarantees optimal machinability.

K390 owes its superior properties above all to the powder-metallurgical production process. The main advantages of BÖHLER MICROCLEAN steels over conventional steels are: • uniform carbide distribution • small carbide size • uniform chemical composition over the entire cross-section and length • virtually isotropic behaviour due to improved homogeneity and the absence of segregations.”

From Phil Wilson on the Spyderco Forums.:
“I have been using K390 from the start ever since it was introduced by Bohler and I got some small samples to try. A bit of history is that it is the European version of CPM 10V but not the exact chemistry (about 1% less V plus small addition of a few others). That is because the CPM 10V chemistry was protected by patent at the time. If you check the K390 data sheet it claims that the bit less V gives K 390 a little boost in impact toughness. It also can be heat treated at a lower temp. than 10v. So it is pretty much the same as the A11 grade but different in a few small details. It is hard to tell the difference between CPM 10v and BU K390 in the real world in my experience. I like both grades and they are the base line (along with Vanadius 10 and K294) from which I measure wear resistance. The 5 chrome is there to make them all air hardening among other things and does not contribute much to corrosion resistance. It is going to make a killer knife in the new offering and be another classic. Phil”

On my Urban, K390 has proven to be very tough. It is my main travelling folder. And it is a real wolf under sheep’skin. One of the little home test I got is by removing the metal around a bottle of wine’s cork. Most of the time, the knife edge is bent and shows some shining due to miss alignement but not with K390. The steel feels like plastic. On my three knives, the Pingo got the most stout blade and less pointy. This little knife is simply used very hard with zero damage to the edge: digging in wood, cut into staples, scrapping various paints and plastic. So far, even if the steel is not stainless, a mild patina has protected it from real rust.

So what do we got ? A tough blade which keeps its sharpness for a very long time. A forgiving edge which can be used by clumsy hands with no after thoughts.
The side effects are: the need of diamonds and ceramics to keep it razor.
Once convexed to me taste, I use white ceramic and some stropping just to get it mirror.

We definitively needs more knives in K390 !

 

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A Spydiechef in Tuscany – Spyderco’s Polish Folding Office Knife

In the ease of maintenance department few knives are easy to live with, the Spydiechef is part of that very small club. You can pocket it while it is still wet. For a travelling knife this is a must and the reason I have taken it for that Xmas Journey.

 

Reuniting with an old friend: the 110V CF Native.

 

When used in the kitchen or on the dining table, knives get dirty and the food is dried and hard to detached. Avoid the use of the green back of sponges or you could scratch the blade’s finish badly.

Hot cheese from that Napolitan Pizza is part of that dirty equation but the plate is also not the edge best friend as ceramic is harder than knives and will ruin any razor sharp knife. You should cut with an angle of 45° on the plate to avoid any real damage.

The Spydiechef is a actually whittling friendly. LC200N is not losing its edge as fast as H1 and I was able to work on wooden rods with ease.

Of course mine has been enhanced with some gentle convexed edge.

But really that knife is really happy in the wood. It has not the most ergonomic handle for hard wood cutting but the gentle belly helps a lot in push cuts.

LC200N is really easy to keep fresh on ceramic. no need of diamonds like on other Hyper Steels.

 

 

 

 

Yojimbo2: swapping the blades back and forth.

My project when I had ordered the Jade Yojimbo2 was to swap the blades with my Carbon Fiber / S90V Yojimbo2, to make a vinegar patina and enjoy a unique CPM M4/ Carbon fiber Yojimbo2.
Yeah well…
I have done it but the patina.

Here is the result. But you know what… As great as the CF handle is… this Jade version got something really special. I love the smoothness I have obtained by sanding the natural G10 and the action is smoother than butter.

So I have swapped it again. It was very easy.
What I can notice about this “sterile” experience is how well adjusted those Golden spawns can be. In both configurations the action was smooth as glass and the blade perfectly centered. It’s a joy to dismount and put back together.
So it’s just me, in the end, seeing the deep carry clip going esthetically much better on Jade natural scales and the heft of the BladeHQ special edition being more appealing to me. Also these transparent slaps help a lot for a non threatening aspect of a very pointy knife. I have already used twice in public place without being noticed…
So back to the start after some nano oiling and putting some fresh blue loctite on strategic screws: pivot and clip. Great knives easy to maintain clean even in the inside.

Cruwear and Patina, the Lemon Edition.

 

Back to trying to get a patina on cruwear after my first attempt.
Because lemon juice is not smelly and we use it a lot in the house, I have tried to let the blade all night in a tissue imbibed.

Tissue seems to be some kind of catalyst as it help to keep a contact between the citric acid and the surface of the blade.

 

In the morning the tissue was dark!

And you can notice rust starting to form in between strokes of the patina.

Rust is removed with some polishing which keeps the patina.

So here we are now with a kind of camouflage results.

It looks forced but should “mild” with uses but yes you can get a Patina from Cruwear with lemon juice and a night…

Which means if you forget your knife in the sink after making some salad, you can get rust on your Cruwear blade and a very swaggy patina.

Patina on Cruwear ? Not that easy !

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Forcing a Patina on Cruwear!
Why?
Because I’m going to the sea and I just need to be certain it won’t pit.
Now Cruwear seems tricky compared to 52100 or Maxamet.
Let see how it will get…

 

45 minutes later… No patina yet some stains…
“It’s not as rusty as 1095 usually, so it’s easy to get complacent. It can go 3-4 days easier than O-1 or 1095 but 3-4 months is a different story. It’s easy to get fooled by steels with this level of chrome ( 8%) as to corrosion resistance. It will appear as a tiny spot of rust. Easy to overlook as it does not make it apparent that spot is deepening, not getting wider. The surface layer of rust covers up the hole. ”
The Mastiff

And he was right…

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Trying to mix oxygen and vinegar using tissues and apple vinegar ?… Nope.

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Apple vinegar and apple sugar under the sun….. Nope.

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Aceto di Modena…. nope.

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Even in the wind…

Naaah forget it. This steel won’t stain beautifully… Just a bit but not enough in my taste.
It will perhaps pit if let unclean some weeks but in my daily uses it should not.

Putting the blade back in the handle the tolerances on that knife are so great you can tight the screws with locktite and pur a drop of nano oil… the pivot is smooth as butter.
Also ten passes on white ceramic and it is back to jumping hairs harvest again.
So cruwear seems to be a very “friendly” steel which doesn’t smell anything when confronted to apple, apple vinegar, various vinegar including aceto … nothing seems to harm it surface.
It is like CPM 3V and will be kept oiled and shiny. My Ed Schempp’s Tuff never needed or develop a patina as my grey Military in Cruwear.
At least I got less worry. 🙂

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Convexing Cruwear!

This time I have decided since the blade of this Paramillie is thin, to protect it with some gaffer tape.

Same process as usual: diamonds, then ceramic and stropping on leather.
The DC4 of Fallkniven and the Spyderco Double Stuff 2 were used.
I got also an old barber leather I use with some polish.

I use the diamonds to remove the shoulder of the edge to round it a little, this is where you can scratch the blade as the angle used is very shallow.
Once you see the edge is widen, you can switch to tsone and ceramics mainly to smooth the scratches made by the diamonds.
It is very simple and just ask for time and patience.

Cruwear is stropping friendly much less than 52100 though.

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Edit of the 24th of September:

More convexing after failing to Patina

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About Locks — How to choose ?

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Nowadays rendering of three iconic 90’s lock: Liner Lock, Back Lock and Integral Lock.

They are plethora of locks since the 90’s when the Tactical Folders trend started.
“Tactical” , a term which has been mainly used in a marketing way, means you can get access to your knife easily — A clip or a well thought pouch — and more important: to be able to open it and close it with one hand.
The blade needs to be locked in open position and also to stay closed while in the pocket.
Let’s have a look on the locks I prefer and use.

20180410_134558-01.jpegMaxamet Para3 Compression Lock.

The Compression Lock.
Described as:
“A lock mechanism that uses a leaf-like spring from a split liner in the handle to wedge laterally between a ramp on the blade tang and the stop pin (or anvil pin).”
What I like about that Spyderco in-house engineered system is how smooth the action is.
Spyderco is now developing and proposing flippers with the CL because the breaking action on the pivot is minimal. On my different CL folders I can open the blade in different ways: using the index, pushing the paddle to unlock the blade…
It’s fun. It depends on a detent ball to keep the blade closed.
It’s a lock easy to clean and check as the handle are all open framed. It also asked for some nested liners which, when they are skeletonized, need more attention for cleaning, especially when you use you knife in the kitchen like I do. I rinse them under hot tap water , wipe the blade and make them dry inside the pocket with body heat.
Also the compression lock can be hurting the palm of your hand when cutting hard matters.

20171208_120329-011500186881.jpegNative 5 Back Lock.

The Back Lock.
Described on the Spyderco” Edge-U-Cation pages as: “A locking system positioned on the back of the handle that uses a rocker arm that pivots in the center. A lug on one end of the arm engages a notch in the blade’s tang to lock the blade open.”

The Manly Peak and the Native 5.
This lock has been infamous since the Buck110 and all its copycats. Spyderco has developed mainly mid-locking system which can be unlock without changing your grip lick on a Buck110. It was demonstrated with the first Native how safe it was it unlock their knife and let the choil of the blade get in touch with your finger before to close it.
This is still the way I do it, even on my Delica and Endura which got no proper choil: unlocking the blade by pushing the lock free and let the blade falling half way on your finger. The Back Lock got a spring which is strong enough to avoid a detent ball. Old timers used to pu a match inside their closed Buck110 to pass the stronger spring tension and get it open faster. On Spyderco’s, it’s also easy to avoid any locking noise just by pression the paddle before it get completely opened. Unless the blade is very heavy like on XL Cold Steel Voyager, it’s not a lock for gravity opening. But it’s one of the most solid lock. In fact because of the way it’s engaged, it can be much more solid than all the other locks. Spyderco were testing their strong back found on the Chinooks and Manix with amazing results.

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It’s not the easiest lock to clean as there is no open framed handle. It’s hard to see if debris can be jammed in. Also it’s not the funniest lock to use as the spring tension is felt during all the opening and closing motion. The Spydies with relatively heavy handles can be spyderdropped for quick opening. I do that on my Knifecenter stainless steel spacered Delica for example. It’s also easy on your palm during hard cuts because of their closed handle spine. Some Compression Lock haters are Back Lock lovers because of that confortable handles.
Also I have noticed on many of my Back Locks knives some vertical play when cutting on board which brings us to…


The TriAd Lock
Featured on Cold Steel’s folders it is essentially a Back Lock with a stop pin. There is no more vertical play when cutting. It doesn’t change anything toward the negative force used to close the lock blade.
You can also find inside the Chaparral an hidden stop pin invisible as it’s hidden near the pivot.

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The Liner Lock.
“A locking system developed by custom knifemaker Michael Walker that uses a leaf-like spring split from the liner to wedge laterally against a ramped surface on the tang of the blade.”
This lock was the king of Tactical frenzyness back in the 90’s. The Benchmade CQC7 and AFCK promoted them in titanium and Spyderco developped their Military with a stainless steel liner lock. If I remember well Sal Glesser and Les de Asis were together private students of Bob Terzuola which is a master in liner locks making before to start their own production. Depending on a detent ball, the liner lock was bringing that smoothness the Back Lock could not provide but it was not the strongest lock available.

wp-image-1554915927Ed Schempp Euroedge strong liner lock.

To test it many people tried the infamous and stupid spine whack and many time with shock the liner was unlocked and damaged by that treatment.
It’s a very easy to lock to get open and close fast just be careful to put your finger out of the way when closing.
Titanium liner locks are wearing more than stainless steel liners.
It should not be difficult to clean depending of the handle conception. On that matter the last version of the C36 Military got rid of they spacer and got now a full open handle for easy check.

The RIL
Then Chris Reeve came with his Sebenza and used a lock bar that is integral to one of the handle scales. It was giving you the sentiment, you hand’s grasp was also enhancing the locking mechanism. It’s also a very easy mechanism to clean and check hence the Spydiechef, or the K2 which are easy to use in the kitchen even after being defiled by grease and meat…
20171130_113248312135934.jpgRIL of the Advocate and the ZT550.

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The PPT is a mix of both RIL and liner designs with the possibility to grasp it and hold it in opening position.


BALL BEARING LOCK
“A patented compressive lock that wedges a ball bearing between a fixed anvil and the blade tang. The mechanism also serves as a detent to hold the blade in the closed position.” I was developed by Eric Glesser for his Dodo and can be found on the Manix 2 folders with a caged ball version. Some people found a lot of similitude with the Axis Lock from Benchmade but here, instead of two omega springs, it is a coil spring pushing a ball bearing made of ceramic of stainless steel. It’s smooth but not as easy to clean as other locks. Actually I prefer it on the Lightweight version of the Manix which is my main travelling knife with its CPM110V blade. It’s engineering makes it one of the strongest as you can not squeeze a ball bearing easily and it is also self adjusting.

The cage ball can be exchange with a custom titanium cage in case of breaking after years of using. It happen to my cousin who has modeled his own resin ball.

The Balisong Lock.
This could be the most fun system to use and also the strongest. Easy maintenance, no spring… It’s a very old design. The first trace was found in 1780 in France with a knife called “Le Pied Du Roy” (The King’s Foot) and circa 1800, butterfly knives were uncommon. They were made in Paris and Thier. There is a beautiful collection of the old Butterfly Knives in the Thiers Museum.  French Army troops were provided with Butterfly Knives, but after WW2 there is no more trace of Butterflies made by this brand.
(More to come in the re-edition of the Fred Perrin’s balisong review soon.)

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Locking a folding blade has been a puzzle for engineers for centuries. The roman folders were not locking and 2000 years ago a folding knife’s handle was considered as an attached sheath which means it was hold like a razor: by the blade.

So how to choose a lock ? Recently I have been surprised on how well the Bulgarian Manly Peak was operating: no vertical or lateral play on its very strong Back Lock. I have been playing with the Sliverax Compression Lock flipping options. My old Sebenza RIL lock is still in great shape and my Ed Schempp Bowie flies in opening position…

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Lock is just a matter of taste and use, selling a design just by its lock won’t work. Some designs are made for compression lock like the Sliverax wasp shape flipper design could not go easily with another lock.

But always remember a folder cannot be as strong as a fixed blade. Marketing can be your enemy but the main enemy of locks are shocks because its weakest element will give in, bend or broke. Now when you choose a knife made by reknown makers and manufacturers you can trust their locks but it’s not the case with all the copycats and cheap knives which often got very bad quality elements ready to break or bend at the first use. I’m not saying the best locks are the most expensive but looking for quality in the making should be mandatory in your choice.