Japanese White Steel Kiridashi Frame Lock

[STR]

I picked this folding Kiridashi Kogatana up at the Japan Woodworker some time ago for just over $20 and some change on a special they had. Its a great blade but the folder was just too long for convenient carry in the pocket, didn't have a pocket clip or thumb stud opening device of anykind for one hand operation and simply wouldn't stay closed reliably enough for me to justify carrying it, especially with a blade this sharp! For these reasons it sat in my safe and was only used on rare occasions for some gardening work and trimming jobs for projects I had going on.

The blade is a super nice traditional hammer forged two layer steel with a hard very sharp edge at 64 Rc forge welded to a spine of softer tougher iron. The bevel on it is right hand. They also offer a left hand bevel for a few more bucks. I believe the usual cost of this knife is $30 plus shipping.

In the original form it was 9.75" OAL when open. It had a 3.75" blade and was 5.5" closed. (see far right picture of before)

In the new body I have shortened the blade to 3" and the folder is 4.5" closed and 7.5" overall. The lock side is .125 titanium and the non lock side is .125 turquoise canvas Micarta. I bead blasted the entire surface and of course I added one of my signiture low rider clips to it, which I also bead blasted.

It makes a great blade even better for me because now I can carry it conveniently as well as open, use and close it after I'm done all with one hand.

Let me know what you think. I'm really pleased with the end result.


STR

 

[jujigatame]

That is nice. It all fits and flows together like it was designed that way from the start. Great work.

 

[Cliff Stamp]

Interesting blend of traditional and modern, I think aesthetically a wood inlay in the handle would be worth considering.

-Cliff

 

[STR]

Interesting thought Cliff. I'm going to be doing two more of these. I may try something different and use a different handle material on the next ones.

STR

 

[Cliff Stamp]

I really like the bend over clip design, it seems more integral to the handle. It might make a good contrast if the clip could be finished to match the flats of the blade.

-Cliff

 

[STR]

I assume you mean with hammer marks like it was forged?

The way I make the clips on my frame locks they do double duty as a lock stabalizer also. Once the lock pushes out so far you are pushing on both the clip and the lockwhen you close the blade which adds to the pressure to keep from pushing the leaf lock back too far. The stabalizing effect is not as rock solid as the one on the Striders but it doesn't have to be because I don't cut out my relief for the lock bend as thin as they do. The relief on mine is .065 thick which is well over the .033 to .039 thickness I've measured on the relief areas for the lock bend on the Striders.

Sal said recently that in their tests the frame locks folded and failed at that relief area which has confirmed what I've been saying all along. A uniformly thick .060 liner lock is probably stronger than a .125 frame lock with a large relief area cut out to .030 plus or minus. The weakest link in the chain theory. But I realize that is side tracking so I'll save it for another thread.

STR

 

[Cliff Stamp]

I assume you mean with hammer marks like it was forged?

Something of that nature, a significant patina might do it as well.

Once the lock pushes out so far you are pushing on both the clip and the lockwhen you close the blade which adds to the pressure to keep from pushing the leaf lock back too far. The stabalizing effect is not as rock solid as the one on the Striders but it doesn't have to be because I don't cut out my relief for the lock bend as thin as they do. The relief on mine is .065 thick which is well over the .033 to .039 thickness I've measured on the relief areas for the lock bend on the Striders.

Do you have any problems with ease of opening them?

Sal said recently that in their tests the frame locks folded and failed at that relief area which has confirmed what I've been saying all along.

I have noticed the same thing by batoning them.

A uniformly thick .060 liner lock is probably stronger than a .125 frame lock with a large relief area cut out to .030 plus or minus.

Yes but the thicker look looks a lot stronger. You can test this of course without making a knife, just load a strip of steel so ground and watch where and how it buckles.

-Cliff

 

[STR]

My first couple of frame locks had some issues with the locks being a bit tougher to push sideways to release them but then I learned two things. With frame locks you can make the thumb ramp access area to the lock release bigger without necessarily compromising the lock security like it may on a liner lock so when you can get more thumb on the lock it isn't painfully pushing into your thumb, and two, the length of the long cut has a lot to do with how easy the lock is to move. Meaning, a longer piece of metal is easier to move or bend than a short stout one.

This frame lock is just as easy to release as any liner lock I've ever done so I think I'm moving in the right direction. I've seen that once the ti is over .075 thick it can be quite hard to not only make the bend in the lock without a lock relief cut out, it can be hard to move the lock sideways also without a 'weakened' spot or relief area so as a general rule I try to take the relief cutout down to a .065 or slightly less thickness on them now. That is the same thickness as the Mini Buck Strider 881 liner lock that has no relief cut out in it and it moves quite easily. They are about the same actually in both feel and the push power it takes to move them. I rate the 881 as one of the better more secure liner locks I've owned. It seems to be more secure than its bigger brother to me. (the 880) It may be the shorter length of the lock and the knife as a whole that gives it a bit more security I don't know. In my experience the bigger a liner lock knife is can make it easier to unlock. Some of my shorter gents folders with liner locks seem to be more secure than the bigger ones I've owned.

STR

 

[Cliff Stamp]

My first couple of frame locks had some issues with the locks being a bit tougher to push sideways to release them but then I learned two things. With frame locks you can make the thumb ramp access area to the lock release bigger without necessarily compromising the lock security like it may on a liner lock so when you can get more thumb on the lock it isn't painfully pushing into your thumb, and two, the length of the long cut has a lot to do with how easy the lock is to move. Meaning, a longer piece of metal is easier to move or bend than a short stout one.

Interesting note about thickness and thumb pressure. I noted this awhile back when handling two knives and one felt lighter in hand and after measuring it and doing a few calculations it should have been heavier but because the force was so well distributed it felt lighter. I can see the same thing readily happening with lock releases but never saw anyone note it directly.

Some of my shorter gents folders with liner locks seem to be more secure than the bigger ones I've owned.

I wonder if this isn't one of the reasons that Joe noted seeing really well done liner locks on small gentleman folders on occasions which were far more secure than on larger tacticals. You really should write up a commentary on liner locks in some detail complete with the pictures you have posted. Sort of a complement to Joe's FAQ about testing them.

-Cliff

 

[STR]

I wonder if this isn't one of the reasons that Joe noted seeing really well done liner locks on small gentleman folders on occasions which were far more secure than on larger tacticals.

Could very well be as I think there is something to be said about the shorter stouter knives vs the longer ones with weaker flexible locks although a couple of those like the Buck/Strider 889 I tested and the Swamp Rat Rat Trap seemed rather secure even if the locks did bend visibly under pressure.


My next frame lock will be made out of the same .125 titanium as this one only with a twist. I'm going to make the next one with a cut out or recess for an inlay of hard stainless in a .040 thickness that is screwed into place on the lock on the area where you depress with your thumb to release it so this piece of hardened stainless as well as a portion of the titanium lock will both hit the blade at the interface when the blade is opened. I've seen far too many ti frame and liner locks indent from hard use and don't see this happening with hardened stainless ones I've made so I think that would be a good fix for the indenting problem when using titanium personally. I'll find out lets put it that way. My idea is that it will provide both the gall or sticking effect titanium is famous for and the hardness and resistance to indenting that stainless is good for. Hopefully the best of both worlds in other words.

STR

 

[Cliff Stamp]

That is interesting. What steel do you normally use for the liners and how is it hardened?

-Cliff

 

[STR]

I have a sheet of 410 stainless I sent off to Paul Bos along with some blades, liners and locks and pocket clips right before his move to Idaho with Buck. Its hardened to the max you can get 410 which is right at 45 Rc. You can use a number of steels for this job. 410,416 or any number of different ones with similar properties. I've noticed 410 is used on some Kershaws as well as other production folders and it seems to be pretty resistant to indenting to me compared to ti. I've made some liner locks out of it that really took a lot of beating and one guy even told me he spine whacked one of them until the handle scale broke off and it took it and asked for more.

My idea for this inlayed piece of hard steel to strengthen the lock at the contact area is also going to make lock adjustments a lot easier to do when they are needed. If say the lock did start sliding all the way across the back of the blade to the other side it would simply be a matter of making a new inlay of hard steel to replace the old one and stick it out a few thousandths more for fresh contact of the blade interface for a like new lock.

BTW, I just sent you an email.

STR