Ray Rogers Handcrafted Knives
Cutting the Lock
With the blade in the proper full open position, take a scriber and mark the liner using the edge of the locking notch as a guide. As you know, the locking ramp slopes at 10 degrees so the side nearest the liner is slightly more foreward towards the blade's point. This is the side of the ramp that you want to use as a guide for the scriber.
The locking notch probably will not extend all the way to the bottom edge of the handle so use a straight edge to carefully extend your mark, like this:
Now we want to mark the length of the lock. Start at the end of the mark you just made. From there, point the straight edge down the length of the handle. Elevate the straight edge so that the narrowest part of the lock will be at least 1/4" wide (when possible, I prefer 3/8ths"). The size of the handle will obviously limit how long the lock can be. On my knife, I marked the length at 2.5" which was most of the handle length. It's difficult to give exact specifications because you can't really predict how much tension will be on the spring due to the different thicknesses and types of materials makers may choose to use. Experience will help with that. The important thing is to be sure the lock will be stiff enough so don't be afraid to make it a bit wide. We can always reduce the tension by removing metal but we can't add more once the lock is cut.
After you have the lock outline scribed on the liner put the blade back on the knife as in the picture below. Holding the blade in the position shown, scribe an arc around the end of the blade. The arc should cross both of the lines that you just drew for the lock bar. Inside the area formed with the arc is where the detent ball must go. I don't normally put detent balls in these cheesy prototypes but I will in this case in order to demonstrate the process for you.
To further illustrate what we just discussed, look at the picture below. Since my camera can not clearly capture such small detail I have drawn it on the picture. You can see the blue lines which define the lock bar and the small blue arc that defines the detent ball area. It is worth noting here that the further you are able to cut the locking notch into the blade, the larger the detent ball area will be.
The red dots indicate the location of holes to be drilled. The metal will bend easier and with less damage if these holes are drilled before the lock is cut free. For the sake of convenience, I drill these holes with the same size drill bit that is required by the detent ball. In this case, I will use a 1/16th ball so a #54 drill was used. The detent ball should be placed as far down the lock face and as possible.
Here the lock has been cut loose. The exact method used to cut the lock varies with what tools you have and there are many ways to get it done. I used a mill with a slotting saw. In the past, I have used a Dremel with a cutting disc and I've also used a jeweler's saw.
After the lock is cut loose and before you bend the spring, take a moment to press the detent ball into the hole that you drilled for it. In my case, the job was done with an arbor press. It can also be done with a nail setter and probably a few other ways as well. Push the ball in far enough that the part remaining above the lock bar surface is about the same height as your washers are in thickness. Then, go ahead and bend the bar.
I generally just do the bending with my fingers and prefer to have a smooth bend along most of the bar's length rather than a sharp bend in one spot, but either can work. Once the bar is bent, grind away that small corner indicated by the green dot. All that's necessary is to remove enough material that that portion of the bar cannot touch the locking ramp. In some knives, when that part touches, the blade may have a slight rocking motion when locked open. It ruins that 'rock solid lock' feeling we all like so much.
Now for the stop bar ....
Setting the Stop Bar
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Ray Rogers Handcrafted Knives
