How to install a detent ball for liner lock?

F

flame boy

Joined
May 31, 2008
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Can anyone direct me to a tutorial on-line on how to install a detent ball on a liner lock knife? Any help on this subject would be appreciated. Thanks.
 
Use a number 53 drill size for a 1/16" ball and what I do is use a flat end punch with a small ball peen hammer to tap it. I use the .015 washer I plan to use in the pivot for the detent placement. What this does is allow the ball to sink so the ball stands up (read sticks out) the same height as the washer is thick. I use a pair of the little tweezers made of titanium sold by Dave at Great Lakes Waterjet and these work well to grab me a ball out of my bin since they are non magnetic tweezers. I place the washer over the hole in my lock and simply drop the ball in the hole using those convenient little tweezers. After that, tap with the punch over the ball using the ball peen to tap it and the phosphorus bronze washer acts as my spacer to keep from tapping the ball in too far.

STR
 
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Its a matter of using the proper sized drill bit. For a 1/16" ball the # 53 drill makes the hole just undersized requiring that the ball be forced into it. The tight fit of the whole size actually does hold the ball permanently in place in the lock. In the times when I've removed a ball for a new one, which is only possible if you can come in from the outside (meaning the detent hole goes clear through the lock and not just part way) based on my experience, it has taken a pretty good tap or push to get the thing out of there. The simplest way I've found to remove one is to simply take that same number 53 drill bit and turn it upside down in my chuck in the drill press and lay the lock ball down on a board with a small hole in it for the ball to fall into when I force it out using the upside down drill bit. I insert the drill shank end in the hole on the outside of the lock and fit it down by hand to contact the ball. Once done I simply lower my chuck down to my board and force the ball out. This doesn't require running your drill press. It usually does take some ummmph to get it out though.

I've seen and installed detent balls using other methods over the years of working on folders. Imagine how you see a diamond mounted in an engagement ring for a second. So, lets say you drilled a 1/16" hole in the lock for a 1/16" ball and now you have a situation where the ball just drops in and sinks in the hole. Depending on the thickness of your lock it may just fall out the other side since the hole is too big. What do you do? Well you simply peen using a small flat head screwdriver north, south, east and west all around the hole drilled in the lock and then insert the ball the same way as if the hole was drilled with a #53 drill bit. Basically friction holds the ball in place either way.

I've seen other knives done uniquely for how to make a detent. I own two with detents done without using ball bearings. One of my favorite little knives, one I have two of actually that I call my PJ knife since I have it clipped to my pajama pants for after I shower and am just relaxing around the house is from Dick Atkinson who is now retired from knife making. This knife has a small 1-70 size button head screw placed in the lock where a detent ball would normally go. It is done with a polished and rounded off screw head.

Dick simply threaded the hole after drilling for it and then inserted one of the same screws used in the construction of the folder itself. I bought the second one just because of this unique detent Dick used and to be perfectly honest with you it works as well as any I've owned using steel or ceramic balls. If one wanted to one could thread and insert a screw leaving just a tiny bit of the stem out and cut the head off the thing rounding off the stem that protrudes and probably even make it function as well as look like it was a ball bearing. Its more work but I figure it would work fine if someone took the time to do it.

STR
 
You are quite welcome. I need to make one correction in that last post. I don't know what I was thinking regarding the screw size Dick Atkinson used because I re-read it and realized what I did. Its .080 button head hex drive screws Dick used not 1-70. Actually it would be 1-72 to be precise if that were correct but the point is its .080 which is a smaller screw. Its so small actually that the things look like the socket to fit the hex driver in there would just strip out if you hiccuped while turning one to tighten it but somehow Dick managed to get them all installed and super tight. I personally don't use a screw this small and instead use a 2-56 for all my folders but thats way big for a detent so if you were going to do that using a button head screw it would have to be small. These really add a fine jewelers look to the knife in this particular folder because they are so tiny that the it gives the whole knife a bit of a mini-version look as if this one was modeled after a bigger folder and made in miniature.

Anyway, other than this the information above is valid and will work if you do it as I describe. I've done hundreds over the last 15 or so years.

STR
 
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