Tuesday 12 August 2014

What does Full Tang actually mean?

What exactly does full tang mean when it comes to knives?

IS it important and does it make a knife stronger?/Better? and Compared to what???

And what is the meaning of "Stronger"?

Let's quickly look at the word "stronger" This means different things to different people and what those people do with the knife. Unfortunately these days as it appears on YT and elsewhere, "strong" means being able to use the knife in all sorts of applications that a knife was never meant to be used in. For example: levering/prying, bashing the daylights out of metal objects, cutting through steel pipes and the like. Smashing down brick walls. Breaking rocks apart with blade or pommel etc etc. Maybe you are laughing right now but let's face it there is a plethora of videos showing this kind of treatment to knives. It's all kind of funny as I grew up thinking that the main job of a knife was to be able to cut effectively, either during hunting, fishing or camping etc. I don't remember having to slice my way through car doors, refrigerator doors, cut down steel piping and stab away at bricks and rocks, I guess I was missing something. AND for military usage I can't remember the last time some military buddies told me they were slicing through car doors, beating the shit out of brick walls or trying to cut through steel cables! Smashing windows, ok, piercing fuel tanks ok, stabbing vehicle tyres ok, cutting ropes and some levering.



In fact I've had manufacturers contact me and ask me just to check I'm not going to bash the sh*t out of their knife have it fail and then slag off the knife and say that it wasn't strong!

If I want a lever I go get a pry bar or destroy a screwdriver/chisel/lump of steel, not my knife!

 I reassure them I'm not doing the above. That's a job for tools from the hardware/demolition  center, if you happen to be near one not counting improvised tools.

All knives no matter how good the manufacturer says they are, will break or become damaged at some point with the above kind of treatment. Look at what EXTREMA RATIO say about their products. I've even had an infamous STRIDER get damaged when I was using it to remove a stuck axel bushing (because I never had the correct tool with me at the time), and I broke a small part of the tip off. If I never did this then the original tip would still be there 13 years later LOL (i did remove that bush replaced it and got mobile!) . Just read the fine print of the good manufacturers and see what they warranty their knives against, you'll find none of them warranty them against abuse even if it's a military end use.



Let's get back to "Full Tang"

So I figured I'd give it a definition: A full tang knife is a knife blade where the tang is pretty much the full width of the knife at the ricasso ie the full width of the ricasso. This piece of metal then will extend along the full length of the handle of the knife. The tang in this case should not be machined out or have material forged from the tang. It will possess holes for fixing of the handle scales (if not a moulded handle) I would call this type of tang a "machined" tang or a tang which has undergone stock removal.

NOW the important point to note is there is NO substance in saying that the full tang knife as I have defined it above is more stronger/rigid/less flexible than a tang which has been "machined out", in other words has undergone some sort of "stock removal" whether by forging, water jet cutting, CNC machining, drilling or hand grinding. A solid piece of metal may not necessarily be as strong as a carefully designed tang which has had metal removed

However, a poorly designed  or heat treated stock removal tang will definitely not be as strong as an equivalent solid tang. I wonder how many Japanese Samurai's Katana's were busting off at the handle???

Why do manufacturers remove material from knife tangs? There are many answers but here are just a several: 

Overall weight savings, Why?

to: reduce shipping costs believe it or not.

reduce/recover material consumed (excess material can be recycled)

increased strength with reduced weight ( imagine an RSJ girder, now image the same piece of steel as a solid chunk, right, it's not going to work is it.)

Reduced overal weight of the end product- obvious handling advantages.

Added flexibility of the tang to prevent accidental tang breakage- for example in tangs which have been narrowed down (I don't mean a "rats tail" tang here BTW).

Finite Element Method (analysis) says they (manufacturers) can!

If this type of engineering/mathematical analyses are used, it can tell the engineer exactly where material can be removed without affecting or compromising the overall safe strength of the knife.
Material can not simply be randomly removed from the tang without some serious consideration to the resulting mechanical integrity in terms of safety. At the least destruction testing should be conducted under controlled conditions.


From a marketing standpoint and practical design standpoint.

There is a certain kind of confidence that comes from those words "full tang" and this marketing strategy is a very powerful one. No one likes to hear about hollow handles with almost no tang, half tangs, rats tailed tangs, stock removal tangs, stick tangs etc. But the fact remains that a well made knife is a well made knife regardless of the tang. The only knives I've busted were ones that were poorly heat treated  and they will always break with a brittle type fracture, usually quite suddenly without warning and with almost no force applied to the blade. The results of this could be serious injury to user or bystanders!


 Design requirement will necessitate a "full tang" and at other times a stock removal type tang. For example knives where the tang is kept the same but the blade shape varies may help to aid in bulk heat treating as the same mass of metal will always be present in the tang.



Product liking on FACEBOOK only shows false impressions 


If  Knife manufacturers encourage people to "like" a product just to reduce the selling price for whatever reason, call it a promotion etc" it can only devalue what could be a useful function of FACEBOOK.  You can see how biased the data (number of likes) as the number of likes in this example bears no reference to whether the actual person really ended up liking the product (ie really like using it vs being disappointed), only that they were influenced to like it in order to possibly get a price reduction. What it does reveal is what the wholesale product price is or what it is close to and how much you could be being ripped off as a consumer.

So if you want to participate, then do so knowing that you may end up just realising how much profit the manufacturers are making from you. Once seen you can't un see it!



Monday 11 August 2014

TRC Knives K1 Field Assessment













TRC KNIVES K1


Click image to see full size
Hi this is a quick preview review of TRC Knives K1
Andrius Tricius the name behind TRC Knives, kindly sent me the K1. Right now I'm in the field, well after I finish typing here LOL! doing a field test of the K1.

Click to enlarge

I was very impressed as soon as I had the K1 in my hands. 
The K1 is a very well manufactured HAND GROUND KNIFE, and it has the finish and style that clearly says this. This image below shows the new Lithuanian  factory setup.


Click on image to see an enlarged view of TRC Knives factory setup










The blade design is a classic drop point too, big on function and practicality. 




 For example, the rounded finish to the tang which ever so slightly protrudes from the scales adding a nice touch not only to the overall look of the knife but also the feel in an un-gloved hand.



The thumb/ finger gimping is simply not roughly ground as an afterthought but delivered with smooth effective radiuses to each notch.



The Micarta scales are blasted to produce a roughened surface texture and they are held in place by tamper proof stainless steel Tri-hole spanner bolts. 




Even the finish here is neat with the bolt heads ever so slightly recessed from the micarta scales, no clumsy bolt head protrusions found on many knives.


TRC knives are hand ground knives, water jet cutters are used for blanks.


The Guts of the K1

The K1 is manufactured from Uddeholm's ELMAX powder metallurgical steel. 
click to enlarge


ELMAX is getting a lot of rave reviews from knifemakers world round and here's why:


ELMAX is a powder metallurgy product. This basically means that all the chemical elements constituting this alloy are very very carefully blended together to produce a homogeneous starting product. Powder metallurgy technology prevents the segregation of alloying elements normally occurring during normal steel production. The steel prior to final products is actually atomized in the process to produce very small particles that solidify very rapidly preventing (almost negligible levels-according to Uddeholm) segregation. This lack of segregation prevents brittle carbide "networks"  from forming in the steel. The result is that bend and fatigue strength are improved.

HRC is 59-60 Heat treatment and temper cycle includes  cryogenic treatment at -196C! That's the temperature of Liquid Nitrogen. This would be very rapid in terms of attaining the temperature of liquid nitrogen (LN), as LN boils with a 14C degree temperature difference and so such small objects and flat in profile such as the K1 will come to -196C fairly quickly.
The purpose of the cryo treatment is to achieve maximum dimensional stability in the finished piece. The cryo treatment is done directly after the hardening treatment preceding any tempering. According to Uddeholm, "1-3 hours treatment" can result in an increase of approximately 1-3 HRC. (see ELMAX PDF)

Here's a schematic of Uddeholm's steel making process (by the way using recycled materials too!)


Diagram courtesy of Uddeholms AB














The K1 is perfect for general camp tasks along with food gathering. I used it a lot for mushroom foraging. 
















Yes it's not a mushroom knife, no super thin blade but it will easily cut mushrooms without making a mess and the same blade can work wood and support light batoning.


























Cutting up fish and game is not a problem either










To round off this product his design of the Kydex sheath 



has a nice touch of an added thumb release area moulded very carefully between the two Kydex plates. 




Pushing your thumb into this region you can easily remove the K1 without a struggle and silently too I might add, if this is what you are looking for. On top of all of that, the sheath really grips the K1 perfectly, there is no need for a secondary retaining strap or like. There is NO chance of the knife coming loose accidently. This is a big feature I like in my sheath designs and will suit a lot of serious bow hunters who actively stalk game. The last thing you want is for your knife to rattle or come loose during crawling or running after game on the move. Because the belt loop 



is made from a piece of flexible seat belt webbing, which is not only tough and abrasion resistant but very strong; the whole scabbard can be placed in a comfortable position during a ground stalk. The last thing you want is a scabbard digging you in the side while you are trying to keep perfectly still for minutes on end! Well done here too! Also this loop is of course as you now no doubt not be surprised can be simply reversed (mine was set up for right handed carrying) for left handers.

Dimensions at a glance of the TRC K1 are:


4.8mm thick
Of course there is a generous lanyard hole.
23.5cm overall length
11.5cm long blade as measured from handle to tip


A Stone washed (this example) or satin blade finish is currently available.
TRC sell for K1 for 239 Euro at the time of writing.

Stay tuned to Bushcampingtools YouTube channel for the upcoming field  video review!

Wednesday 6 August 2014











Lionsteel M7 and Sleipner steel





Ok here are my views from using the Lionsteel M7 for 2 weeks solid in the field. Just to set the picture of the testing grounds. The river is flooding and broken it's banks only 200m from where I'm sitting in this small village with dirt roads and where the locals still use horse and carts-ok get the picture. It's wet and wild.

I've got to say that I think Uddeholm Sleipner is not as good for knives as D2. It's use for outdoor knives is a secondary function in terms of it's original applications, ie in the tooling industry. For a start my Kizlyar Supreme Maximus made from D2 does not suffer from the rusting like the Sleipner. Yes, I know Sleipner has even less Chromium (Cr) than D2, quite a lot less. My D2 blade has never chipped but my Sleipner alloy blade of the M7 has multiple chips from some rather light work, in fact more chips than my Cudeman 299B made from Bohler's N695, ie 440C steel!.Sleipner is supposed to be better at resisting chipping than D2 under equivalent conditions.
The blade of the M7 I have was pitted within minutes of use. I crossed a river on foot which took about 2 minutes to travel about 20m or 60ft (it was almost waist deep and flowing very fast). I did some lightweight chopping and some food gathering (cutting).

The tip of the blade was submerged for about 2 minutes during the river crossing. 

By the way the liquid you see on the blade is NOT water but sunflower oil.

What did Uddeholm say? No reply so far or acknowledgment of my email.

Now a cold fast flowing river in flood is going to contain lots of dissolved oxygen and dissolved salts as well. if the metal is susceptible to pitting it's possible to happen. ie corrosive pitting-IF there are sub-surface, surface defects, and/or impurities within the steel close to the surface. BTW I didn't make this up Google corrosive pitting read the relevant papers, I did.

Is this acceptable for such a knife? Is this a fault of knife manufacture or is this a raw product fault? ie the starting product from Uddeholm was at fault to begin with? Is it a fault at all??

Well if I was in the business of making tools from the Sleipner alloy for it's intended purpose, I might also PVD them, in which case this ceramic nitride coating will help protect the surface from corrosion. BUT I may not PVD them and so would be disappointed if I saw this happening to my tools.

Certainly observation of blade surface by an unaided eye, it was smooth and clean- LionSteel's satin finish! But of course things can change during heat treatment if not done correctly. One side of the blade is not so badly affected. Corrosive pitting effect can be a problem if left unchecked. Small holes can enlarge in all directions, into and away from the initial site weakening a structure.

Here are some macro images of the corrosion. What we see here is a classic example of pitting corrosion where the corrosion is localized, forming pits on the surface. Unlike the type corrosion seen, for example on a basic carbon steel, where the corrosion would be more evenly distributed.

















Click on image to enlarge
















Corrosive pitting is a real problem when it occurs on the blade as it can significantly weaken it's structure if left unattended or unnoticed. You may not see the pit as the brown stain from iron oxides can obscure the actual pits and corrosive forces will continue.

Protecting from oxygen is one way to deal with this but corrosion need not occur only via  oxygen exposure.

In an earlier blog I said the M7 IS NOT for coastal camping and I stick by this unless you have plenty of fresh water to wash it off immediately then you will have lots of rusting.

Any outdoor use knife is exactly what the name implies, it should be good for outdoor use and that means occasional subjection to liquid water, water vapour, dirt, blood and guts and other animal products, potentially corrosive plant saps (there are many, did you know this?), sweat (contains salt NaCl!), salted meats, and plant acids (fruits).

Since this M7 blade did not corrode all over I'm going to suggest that this pitting seen is a defect in the overall homogeneity of the alloy.


Again I want to know what Uddeholm has to say, ie is this normal or abnormal.

If you have read this far then you will now know that a link to this blog has been posted on Blade forums as well in the LionSteel manufacturers area.

Of course once the steel leaves Uddeholm then the heat treatment is not there responsibility, it's the responsibility of the (in this case) the knife manufacturer.

Camping or working around rivers can be tough on a knife, almost everything you cut near water level or material that has been previously submerged will be abrasive (containing mineral particles from silts etc) if the river is prone to flooding. That means collecting herbs for tea making, chopping wood or carving woods that were previously submerged can be abrasive on a blade cutting edge and general faces of the blade. So the last thing I want is to see corrosion like this occurring on or near the cutting edge.



Remember the Lionsteel M7 is NOT guaranteed against anything except cutting tasks and manufacturing defects.


More to come stay tuned!


Ok here is what Uddeholm had to say re the images:




"Looking at the photos I do not see the corrosion as something unexpected. Neither Sleipner or D2 are corrosion resistant steel grades and are considered to have a similar behavior in contact with water. The lower Cr content of Sleipner compared with D2 does not affect the corrosion resistance in any significant way since it is the Cr content in solution in the base steel that determines that. You cannot just look at the Cr content of a steel to determine how corrosion resistant it will be. You have to take into account also the carbon (C) content and other alloying elements. In both D2 and Sleipner almost all the Cr is tied up in the carbides that give the steel its wear resistance. In D2 you have both a larger Cr and C content, ~12% and 1,5% respectively, which result in more carbides in D2 than in Sleipner with ~8 % Cr and 0,9 % C. But both have approximately the same amount of Cr remaining in solution. However, what is left in solution in both grades is much less than the minimum of 12 % Cr in solution required for a corrosion resistant steel. Compare with our Elmax which has 18 % Cr + (3 % V and 1 % Mo) to react with the 1,7% C to achieve more than 12 % Cr left in the base steel and become corrosion resistant.

The extent of corrosion here is perhaps a little worse than I would expect after only a few minutes in water but the extent of attack is also affected by other factors like for example the surface finish and how the steel has been heat treated. In this case it seemed like the surface finish of the knife in the photo was a little rough aside from the grinding which could have contributed to the fast attack. It could also be due to the heat treatment since that will affect both Cr content in solution and also how the carbides are distributed which can in turn affect the speed of the corrosion attack."

Ok Ok I forgot the Cr in solution-pretty dumb of me and careless but........
Let's clean up the blade now with metal polish and see what happens over the coming weeks use. Stay tuned!