Seeking advice

21 is a fantastic design and I love my 21s. All my 21s are special graphic 21s, but if that was all they offered, I would have no qualms about carrying one. Talk to Lone Wolfe or bhyde about getting you added to the facebook group if you're interested. Also if you can find a dealer near you, sec let me check

Maryland

Elkridge, Accurate Pawn & Tackle

Frederick, Edgeworks Knife & Supply

St. Leonard, Ye Ole Cutlery & Gift Shop

(These are listed on the CRK webpage under find a dealer.)

Highly recommend going and putting your hands on a few. Fear not though, nobody stops at just one.
 
Amoo said:
Quick and dirty even though it's a bit more complex:

21 Smaller pivot with bushing no loctite needed, no handle grooves, and smaller washers. 25 larger pivotwith smaller washers, requires loctite, handle grooves. Inkosi larger pivot, larger washers, , handle grooves, angled pocket clip wider backspacer requires locktite.

If I'm incorrect about this evolution somebody please correct me as I do not own a 25. But essentially the 25 was considered an update to the 21 and the Inkosi was considered the update to the 25. Basically if they named it the Sebenza "insert random name or numbers" there wouldn't be as much discussion about it as there is IMO.
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The "pivots" are actually the same size. I'll go search for the thread but kidcongo showed awhile ago that the holes in the blade are or the same size, it is just your interpretation of whether the bushing is part of the pivot. Either way, the fail point comes down to the screw which are the same size I think. I'll look for the thread... It's interesting. For the record, I don't own an inkosi or 21 so no dog in this fight, just love this thread and post. One of my all time favorites by kid...

Edit... Link... http://http://www.bladeforums.com/forums/showthread.php/1152566-A-tale-of-three-pivots-Dispelling-some-myths-about-CRK-folders-(maybe)?highlight=Pivot+size
 
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Nrthfce said:
The "pivots" are actually the same size. I'll go search for the thread but kidcongo showed awhile ago that the holes in the blade are or the same size, it is just your interpretation of whether the bushing is part of the pivot. Either way, the fail point comes down to the screw which are the same size I think. I'll look for the thread... It's interesting. For the record, I don't own an inkosi or 21 so no dog in this fight, just love this thread and post. One of my all time favorites by kid...

Edit... Link... http://http://www.bladeforums.com/forums/showthread.php/1152566-A-tale-of-three-pivots-Dispelling-some-myths-about-CRK-folders-(maybe)?highlight=Pivot+size
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If you read that thread and my post, you would see that is not really true.
 
bhyde said:
If you read that thread and my post, you would see that is not really true.
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Interpretations vary, plus, screw sizes, as I mis-stated, are not the same size. In other words there's a couple things I got incorrect in my post but it's still a great thread topic to bring up on pivot "size". In the 21 the bushing does not move so technically is that part of the pivot? It is for sure what the blade and tang pivot around.
 
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Nrthfce said:
Interpretations vary, plus, screw sizes, as I mis-stated, are not the same size. In other words there's a couple things I got incorrect in my post but it's still a great thread topic to bring up on pivot "size". In the 21 pushing does not move so technically is that part of the pivot? It is for sure what the blade and tang pivot around.
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It is a great topic, but that one particular subject is just not quite correct. I would say it would be correct if you could put the pivot from an Umnumzaan or Inkosi into the large sebenza. That would take a pretty big hammer to accomplish.
Yes, the hole in the blades is the same size and if you didn't have to worry about the scales, it would still only be somewhat true. The pivot barrel on the 21 is a smaller threaded barrel than the Umnumzaan or the other variants that use it.
Does it make a difference in strength? Sure, but by the time you overcome the pivot barrel that is in the 21, you have bigger problems like, why would it need to be stronger and what are you doing to that poor knife?
 
Not an expert, but since the 21's barrel bushing is firmly held between the scales, IMHO the 21's system would likely be stronger in as much as the threaded fasteners are merely squeezing the scales together vertically with no (or at least less) "torque" being transferred laterally to said threaded fastener directly. On the non-barrel setups the blade directly works the threaded fastener with only the "walls" of the holes in the scales reinforcing the threaded fasteners. Oh boy this theoretical thinking is fun...

:)
 
Officer's Match said:
Not an expert, but since the 21's barrel bushing is firmly held between the scales, IMHO the 21's system would likely be stronger in as much as the threaded fasteners are merely squeezing the scales together vertically with no (or at least less) "torque" being transferred laterally to said threaded fastener directly. On the non-barrel setups the blade directly works the threaded fastener with only the "walls" of the holes in the scales reinforcing the threaded fasteners. Oh boy this theoretical thinking is fun...

:)
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Never thought of it that way, makes sense.
 
The barrel of the pivot for the 21 is 3/16 (.1875in) outside diameter with a .109in inner diameter (tap drill size for 6-32). This is a .0392 per side wall thickness before threads.
The barrel of the pivot for the Umnumzaan is ~5/16 (measured .317in) with a .159 inner diameter (tap drill size for 10-32). This is a .079 per side wall thickness before threads. Double the thickness of the 21.
The failure point is at the plane below the scale if you could exert enough force on the blade on the 21 as that is where the diameter of the pivot barrel changes diameter with the pivot bushing.
The failure point for the umnumzaan pivot doesn't exist in the same plain as the 21 because there is no reduction in diameter through both scales.

And yes, theoretical thinking is fun :D
 
bhyde said:
The barrel of the pivot for the 21 is 3/16 (.1875in) outside diameter with a .109in inner diameter (tap drill size for 6-32). This is a .0392 per side wall thickness before threads.
The barrel of the pivot for the Umnumzaan is ~5/16 (measured .317in) with a .159 inner diameter (tap drill size for 10-32). This is a .079 per side wall thickness before threads. Double the thickness of the 21.
The failure point is at the plane below the scale if you could exert enough force on the blade on the 21 as that is where the diameter of the pivot barrel changes diameter with the pivot bushing.
The failure point for the umnumzaan pivot doesn't exist in the same plain as the 21 because there is no reduction in diameter through both scales.

And yes, theoretical thinking is fun :D
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Of course I easily could be wrong, but my theory is that the threaded part on a 21 would be primarily (and perhaps exclusively) effected in a vertical "jacking" manner while the barrel bushing bears the lateral "torquing" force, transferring the stress in the vertical manner to the threaded parts. It that were true, essentially the threads and cap of the fastener would be the failure part rather than the "body" of the threaded fastener. Ok, I think I need an Advil now...

:D
 
Force applied to the blade through the scales

Familiar with FEA? (finite element analysis)
I have only done it a handful of times in my career. Definitely need to learn more about it. Kindof cool to look at.
I have a CAD model of the Umnumzaan I applied force to. If I only had CAD for the venerable Sebenza to compare ;)
It would take ALOT to beat the Umnumzaan. This is 5000lbs of force applied where the pink arrows are pointing with the scales being fixed at the bottom where the green arrows are.

 
Hot dayyum, that is some cool stuff!!

I guess the force I was thinking about is the dreaded prying force. Never even considered forces in the normal "proper" cutting direction (unless I'm interpreting the diagram wrong of course). I guess I'm a bad boy, thinking in this abusive way. :eek:
 
^^^ Bitchin'! Is there any difference in pivot size between the old pivot and new pivot on the umnum?
 
Officer's Match said:
Hot dayyum, that is some cool stuff!!

I guess the force I was thinking about is the dreaded prying force. Never even considered forces in the normal "proper" cutting direction (unless I'm interpreting the diagram wrong of course). I guess I'm a bad boy, thinking in this abusive way. :eek:
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I probably missed the point of direction where you were thinking. The direction I have always just thought about is a lateral force that is perpendicular to the axis of the pivot.
You are not interpreting it the graphic wrong. I can probably open the blade in CAD and put force around the pivot but I don't think it's going to change much if any around a circular object. This was just a quick example that it would take alot to break this arrangement the way they are designed.
It's really too bad that there isn't any inflection in text..these conversations are fun to have but my opinion is just that. It's not the end all, be all. My thoughts are based on some limited experience with what may be faulty data provided from somewhat unreliable sources...but I do have some cool tools to work with!! :D

Nrthfce said:
^^^ Bitchin'! Is there any difference in pivot size between the old pivot and new pivot on the umnum?
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Not that I am aware of. Can't imagine changing the diameter of the hole in the blade and the pivot diameter when they transitioned to the newer pivot.
 
I received my 21 today! So impressed by the whole presentation: the packaging and the cloth and everything...

Oh, and the knife!
After making my decision I was reeeeeally nervous that I should have gone with a large. However, I'm pleased to report that the size of the small is absolutely perfect for me. Handle length and blade length it's very comparable to the other knives that I tend to carry, all while being in a much sleeker package.

I am so, so, so thrilled to start carrying this and using the snot out of it. I'm already thinking about what I can sell to fund my next CRK.

Thank you everyone so much for the recommendations! I am beyond thrilled to finally own a Sebenza! Woohoo!
 
VermontEdge said:
I received my 21 today! So impressed by the whole presentation: the packaging and the cloth and everything...

Oh, and the knife!
After making my decision I was reeeeeally nervous that I should have gone with a large. However, I'm pleased to report that the size of the small is absolutely perfect for me. Handle length and blade length it's very comparable to the other knives that I tend to carry, all while being in a much sleeker package.

I am so, so, so thrilled to start carrying this and using the snot out of it. I'm already thinking about what I can sell to fund my next CRK.

Thank you everyone so much for the recommendations! I am beyond thrilled to finally own a Sebenza! Woohoo!
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^^^So much win in that - enjoy and CONGRATS!
 
I too went with a 21, a large, after reading this thread and everyone's help. Pics when it arrives.

Sent from my LGMS428 using Tapatalk
 
Heirphoto said:
I too went with a 21, a large, after reading this thread and everyone's help. Pics when it arrives.

Sent from my LGMS428 using Tapatalk
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Right on! Glad this thread was helpful to someone else as well. Let me know what you think when you get it. I'd love to hear your thoughts on the large. I'm loving the small bit of course I have that "what if..." feeling about the large.
 
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