Flaring the Tang to Ease Over the Detent Ball

[Mad Mac]

Maybe I'm the only one who notices, but after years of smooth operating back locks, the "two-stage" liner lock feels like hitting a curb stop in a Cadillac. Here is what I mean by "two-stage".

When a liner lock knife is open, to close it the spring is pushed back to clear the tang. Once the knife begins to close, the tang then engages the ball on the spring (the one that will hold the knife closed by means of a detent in the tang). Force can be applied to the blade to override the ball or the spring can be pushed again to allow the tang to clear the ball or the spring can be held down from the beginning until the tang clears the ball. Here is my solution.

A tiny flare or partial chamfer the height of the detent ball, should be machined into the edge of the tang so that the tang can effortlessly ride over the ball on closing. This would not interfere with the lock because the spring engages the lower part of the tang to lock it and the detent ball interference involves the upper part of the tang.

Am I being ridiculous? Would anyone pay an extra few dollars for this feature? Should I apply for a patent?

[bearfacedkiller]

The Para2 has this feature.

[Evil D]

Yep this has been done on several models and wouldn't be hard at all to do with a Dremel. You could even grind the tang into a smooth ramp that the ball could slide up on and you wouldn't feel the impact at all.

[Sharp Guy]

I use the ball/curb stop to help close the knife. I push the liner over with my thumb to unlock the knife, then I use my index finger on the back of the blade to slowly move it the until I feel it stop against the ball, then I give the back of the blade a light tap with my index finger and the blade flies closed. Just make sure your fingers are out of the way! I do this with my Sage 1, Sage 2, and Persistence. Yes, if there was a smoother transition over the ball maybe I wouldn't have to do the first step and move the blade until it stops against the ball but I think that pressure against the ball is what helps to close the knife so easily.

[Mad Mac]

To the best of my knowledge, the Para 2 and other Military models are compression locks with which I am not familiar. A little Googling, however, indicates that there seem to be issues with the detent ball and tang interference for that model as well.

The Mad Mac Flare might help with compression locks but my original intent was aimed at conventional liner locks. Can anyone provide a citation or image for a solution like I described? Googling is unable to provide one for me.

Yes, this is a modification that individuals could do. However, great care should be exercised so as not to inadvertently chamfer the locking portion of the tang as serious injury could result from the liner overriding the tang and the lock failing suddenly. Make the modification at your own risk.

To help visualize the Mad Mac Flare, below is a photo of a lowered and flared ejection port on a pistol. The flare is the scooped out portion on the left of the port. The Mad Mac Flare would be tiny, a tenth of an inch or less, and would be on the edge of the tang that engages the detent ball.

[bearfacedkiller]

The Para2 did not have the ramp originally and it was added later to address the issue. I believe people were actually damaging, wearing or losing the ball. I cannot remember what exactly was the problem but it was more than just the feel of the lock that caused the change.

It would be the same on a Comp lock or a liner lock but just be in a different spot.

Here is a pic I stole that shows the Para2 ramp. Your Mad Mac flare has been done already unless I am misunderstanding you. If you don't have one on a knife and want to add it it should be easy enough with a brown sharpmaker rod's corner. The ball should leave a mark showing right where to put the notch. It should be an easy mod. It would just depend on where the detent ball is in relation to the lock interface on a liner lock. It may work better on some than on others.

[bearfacedkiller]

Here is a thread with a few more pics of the ramp that I found with a quick google search.

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[Mad Mac]

This was my first attempt at disassembling and reassembling a Spyder and my first mod. For the project, I selected two Tenacious Value Folders I have, providing a folder inexpensive enough to risk ruining and a "control" knife for comparison. My full SE I need for work cutting netting off round bales so the CE became my expendable "test mule".

As suggested by the bearfacedkiller, I used the Tri-Angle Sharpmaker medium stone to shape the flare, basically an elongated, rounded notch. The fine stone and ultra-fine stones I used to smooth it up more.

Positioning the tang with the center of the pivot hole over the edge of a block (a large paperback book) and the edge of the tang that engages the detent ball also on the edge, I held the Tri-Angle stone perpendicular to the block edge so as to engage the arc of the detent ball track at a tangent.

After several trials, I stopped. The verdict is that it made a difference. The hard stop is now much softer, still noticeable to me because I was feeling for it, but much softer. A longer flare would provide an even more gradual transition but I'm satisfied that the idea will work.

Will I do the flare mod to my other knives? Probably not, but then I am famous for having a very low energy level. It was fun, though, to see if the idea would work. Your mileage may vary.

[Mad Mac]

Thank you, bearfacedkiller.