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Special Forces by KATZ KNIVES

Sergiusz Mitin

Sergiusz Mitin

Joined
Nov 25, 1999
Messages
1,499
Hello Friends!

Here you can find my new writing in French Guns-World Net on-line magazine.

Please leave your comments and ask your questions here.
Soon I'll publish some quick edge retention test for this knife putting it against two SPYDERCO's.
 
Hey Sergiusz,
As always, great review.
I especially liked your comment about blade sharpening and blade dulling being the same thing. It makes perfect sense and I never heard it put that way.
I'm surprised that Katz knives are not more Popular.
I used to have a Katz Lion King fixed blade. It was quite a large knife with the most beautiful blade shape I ever saw. However, the handle wasn't very conducive to heavy use so I sold it. I had the Kraton handle version, but I think they also make a micarta version of it. This might've been a better heavy user.
Cheers,
Lenny
 
Hello Sergiusz,
thank you for your review. I appreciate it very much. I would like to ask you how would you compare and rate this knife's strenght and its lock in relation to other lockbacks and their locks,like Spyderco Endura for example? Let me explain what I'm interested in. I own a Spyderco Endura, and during cutting when I apply even fairly moderate pressure,like cutting through thicker cardboard(not to mention wood),the blade and the locking bar move in relation to handle.The blade moves upwards and locking bar goes into handle.It's not great movement,but it's very bothering. I know I'm dealing with a folder,but this knife (spring) is ridiculously weak (soft). I'm not reffering to usual aspect of lock strenght (which is: potential closing on ones fingers aspect = negative load?) as other do.I'm interested how other folding knives,a lockback in this case, deal with positive load. I'm interested how Katz SF folder stands at this ? Does its blade also move when some fair amount of force applied due cutting.If it does, how much force it takes to move the blade? Also,in your opinion, how much force ( pressure at cutting) would it take to deform/wear off the lock and locking cam on Katz SF?
I hope I didn't put all this in too complicated way.
 
Son of Triglav,
I understand what you are asking about. Yes, Special Forces has the same blade play under positive load. More, I have tried all my lockbacks and they all have this play including SPYDERCO Delica (I do not have Endura), Calypso Jr. Ltw., Chinook, Dyad, TIMBERLINE Special Service (btw, designed by SPYDERCO) and some others. I think this is the issue of necessary tolerances. The lock catch has to be pushed (by spring) into notch at blade's tang, right? If its both working surfaces - front and rear - would be strictly parallel it would be enough even minimal obstruction (dust for ex.) to cause lock to fail completely, the catch simply would not match the notch anymore. So one of these surfaces should be very slightly slanted to cause catch pack tightly into the notch. It is impossible to slant rear surface which becomes loaded when negative load is applied - this would cause lock to be unreliable and dangerous. So it is no another choice as to slant the front surface, which is loaded when cutting. This cause very slight play (really 0,0X mm only) at this point but you are feeling it on the blade where it is multiplied according lever principle.
So the user have no another choice as to reconcile oneself to this back lock property. Alternatively to use another locking device if he or she can't reconcile...

Please drop here a note did I managed to make this matter clear or you would like me to sketch it?

As to strength issue. SPYDERCO Endura is lightweight folder with pure plastic (fiber reinforced nylon) handle. Quite naturally it should be far weaker than Special Forces with G-10 handle reinforced with double aluminum liners and full length steel backspacer and locking bar. To check how much weaker it is no another way as to break both knives measuring breaking force. So far I'm not planning such evaluations and do not have suitable equipment
smile.gif

Evaluating roughly a tactical folder with G-10 scales and double metal liners should be at least twice (?) as strong as lightweight knife with similar dimensions.
Does someone have some data or ideas for this comparison?
 
Hello Sergiusz,please excuse me I'm late with reply. I aprreciate very much you took time in order to answer on my question. Though I'm not really sure we mean on the same thing. I think I understood what you mean,however I can be wrong.Can you please sketch it I will be sure ? This blade play you mention ,only 0,0x of mm ,is barely noticeable,especially in relatively little used lockback folder. The "play" I meant on, is much greater ,a couple of mm at the tip of the blade. I meant on case when blade and lock bar move together in relation to handle when upward pressure is applied to the blade.But there is no noticeable movement between blade and lockbar. At least it seems to me in this way. I think this kinf of blade "play" is more specific for backlock which have lock position in the middle of the handle,like Endura for example,than a classic lockback(lock at the end).In my opinion,it happens because the spring is not strong enough. Anyway, thank you for your answer.
 
<a href="http://albums.photopoint.com/j/View?u=222944&a=2716881&p=41373556&Sequence=0&res=high" target="_blank"><IMG align=right SRC="http://albums.photopoint.com/j/View?u=222944&a=2716881&p=41373557&Sequence=0&res=high" border="2"></a>Here the sketch is, please click it to open enlarged image in separate window. It is not any particular knife, just a scheme to illustrate what said previously.
If we deal with tactical folder with about 100 mm long blade the pivoting radius displayed on the scheme could be about 10 mm long. If the tolerance would be about 0,05 mm (quite tight tolerance for this class of product) this is easy to calculate blade tip's wobble. It could be about 0,5 mm under positive load - not enough serious to obstruct anything but quite noticeable and maybe irritating for some persons.
I think really the tolerance and as result - tip wobble are somewhat bigger, especially on hard-used knife. Unfortunately I have not adequate equipment in my home to measure it.

I would greatly appreciate if someone could do it and publish results here.
 
Thank you for the drawing Sergiusz. Then I imagined correctly what you meant,though I did not wholy understand it . As for your explanation regarding this problem. I appreciate it ,before I wasn't really aware this could be because of tolerances between blade tang and lock bar. However I also think that (big) part of the problem lies in that particular spring-it's too soft. About my Endura,it is relatively new,also it has seen very little use so far (because of mentioned irritating behaviour). So I would say this "play" is "permitted" because of both tolerances(between blade and lockbar) and also because of soft (or weak) spring.A stiff spring wouldn't allow such movement of the lock bar thus the blade would move significantly less. It would be interesting to compare Cold Steel Voyagers vs. Endura regarding this matter.
 
Actually, the spring strength has very little to do with the effect, and it is almost completely a tolerance issue. The reason is exactly the same lever principle.

You can apply significantly greater force on the blade than virtually any spring can compensate for that you could still close. In an extreme case, I have seen the lock give and the blade continue to rotate open. It is something to check for, particularly in more inexpensive knives.

I have seen some custom makers solve this particular problem by very carefully shaping the head of the locking bar and the cut out in the knife so that after a minute amount of play, the two jam together, rather than continuing to slide. Off hand I can't really think of anyone who does it, but it is a good idea to check it when purchasing.

Now, as a side issue, I used to have a Spyderco Endura, which I also thought had a weak leaf spring in the lock. Primarily because there were a number of times where I would open the knife, begin to use it and then hear the lock engage. Essentially, unless the blade was exactly aligned open, the spring was not strong enough to engage the lock. Eventually I ended up selling the knife and moving to a higher grade product. (Kershaw Ti - 34 1040 model - the first of
their new high tech folders)
 
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