Folding knife rough detent issue?

[blkspade99]

Kinda hard to explain whats going on so I'll try my best with pics. Ive successfully made a few folders that came out great, and I'm tweaking my process and builds to be more accurate and less of a headache at the end of the build of tweaking.

Just finished putting in the detent. When I leave one side of the scale off, and hold it with my finger, the knife is super smooth. I'm just simulating the lockbar being bent. I have some smaller screws, and I'm able to crank the pivot screw super tight. Everything glides on ice.

Now, when I add the scale ( its a piece of teak ) For some reason the action just loses the smoothness. Feels alittle rough/dirty. I'm sure you can imagine. Take it back off and its back to normal.

I know the blade isn't hardened yet and it will make a huge difference but I can't figure out the logically why this would happen. I really can't wrap my head around the scale just distributing pressure equality messing it up. I mean its a thicker liner so thats what's keeping everything flat and aligned.

The only thing I can think of is the length of the pivot. Without the scale its able to screw in almost all the way, whereas the liner you still prob have thread showing inside. But how would that cause the action to lose its smoothness?? I dono I just can't wrap my head around it and want to know.

Knife is in rough shape, don't judge. It will be really nice looking at the end! lol
Also, I have another one I'm making along side. Diff type of scales. Does the SAME thing.

Thanks!!!

 

[Stacy E. Apelt - Bladesmith]

If the pivot shaft isn't seating right in both liners the movement will be sloppy and may bind. You may need a longer pivot.

 

[blkspade99]

If the pivot shaft isn't seating right in both liners the movement will be sloppy and may bind. You may need a longer pivot.

Worth a try. I ordered a couple longer ones just to see. I mean I'll end up recessing the pivot heads at the end even more so hopefully it just fixes it but I'll def. give a longer one a shot.

 

[bladegrinder]

It kind of sounds like your detent ball may be standing proud of the liner on the scale side, so when you but the scale on it's pressing the backside of the detent ball into the blade. if that's what's happening you can either grind the detent ball flat with the liner or drill a shallow hole in the scale for it to recess in.

 

[blkspade99]

It kind of sounds like your detent ball may be standing proud of the liner on the scale side, so when you but the scale on it's pressing the backside of the detent ball into the blade. if that's what's happening you can either grind the detent ball flat with the liner or drill a shallow hole in the scale for it to recess in.

It might look like it in the pic but its not. Its in .018 and the liner is like .030. Its perfectly flat on the scale side

 

[gudspelr]

I may not have seen it in your pictures, but here’s something that helped me-did you relieve the inside of the scale or the scale side of the lock bar for the amount that the detent ball is proud?

If your detent ball is sticking out (towards the blade), say .020 (just using round numbers), and you’ve got a washer of .010, then at least .010 of material has to be removed from the other side of the lock bar or the inside of the scale. If you don’t, then the scale gets screwed on to the liner and pushes the detent up against the blade (unlike your finger that gives a little). This gives you more friction and drag than you want when opening/closing. When the blade is closed, the detent ball seats in the hole you’ve put in the blade-no problem. It’s when you’re opening or closing it that the excess thickness caused by the ball can cause problems. Taking .012 or so off the inside of the scale where the lock bar is let’s the blade push the bar out enough as it’s opening so it doesn’t bind.

This may absolutely not be the issue you’ve got going-just thought I’d share just in case. Hopefully the explanation makes some kind of sense . Good luck and hope you get it figured out. The fine tuning can drive a guy nuts on folders.


Jeremy

 

[blkspade99]

I may not have seen it in your pictures, but here’s something that helped me-did you relieve the inside of the scale or the scale side of the lock bar for the amount that the detent ball is proud?

If your detent ball is sticking out (towards the blade), say .020 (just using round numbers), and you’ve got a washer of .010, then at least .010 of material has to be removed from the other side of the lock bar or the inside of the scale. If you don’t, then the scale gets screwed on to the liner and pushes the detent up against the blade (unlike your finger that gives a little). This gives you more friction and drag than you want when opening/closing. When the blade is closed, the detent ball seats in the hole you’ve put in the blade-no problem. It’s when you’re opening or closing it that the excess thickness caused by the ball can cause problems. Taking .012 or so off the inside of the scale where the lock bar is let’s the blade push the bar out enough as it’s opening so it doesn’t bind.

This may absolutely not be the issue you’ve got going-just thought I’d share just in case. Hopefully the explanation makes some kind of sense . Good luck and hope you get it figured out. The fine tuning can drive a guy nuts on folders.


Jeremy

Thanks Jeremy! Actually I don't do any relief on the scales. One of my first folders I made came out amazing without the relief so i figured it was never a big deal. It actually makes sense though and I'll def try it! I don't own a mill yet, so I'll have to attempt it on the drill press with a endmill. I don't normally care for titanium scales so it shouldn't be a big deal to do it with the drill press. Mostly like wood, carbon fiber or resin scales. Should I just mill out half the lockbar? Or should it go all the way down to where the cut starts?

Thanks for the advice!!

 

[gudspelr]

Hmmm, I’m trying to remember what I do on the ones I’ve made. I think I relieve material to the lock bar cut out so there isn’t an obvious “shelf” when looking at it. If that makes any sense... When the blade is in the closed position, there’s a slight gap between the lock bar and the scale. But when I swing it open and the detent is riding on the tang, the lock bar is pushed outwards almost all the way to the scale. When the rubber hits the road, if the lock bar will open up okay, how far you take that relief cut is a matter of aesthetics. If a guy really wanted to, he could put a shim under the scale at the detent end, leaving a tapered relief all the way to the lock bar cut out. Would serve the purpose needed and look really nice without having to take off more than is needed.

I hear you on not having a mill. It was a big day for me when I got mine. With your scale material not being Ti, I would think you should be able to use an endmill like you’re talking about. Go slow and take shallow cuts and it should be a nice little relief for your lock bar.

Jeremy

 

[Daniel Fairly Knives]

Find any way possible to move that lock bar the opposite way temporarily then grind it flush. I'd use some double sided tape and a washer or anything to make it stick out... put the tape on something flat like G10, put the washer under the area where the detent hole is then press the whole thing on the tape. Grind the lockbar where it now sticks out. I hope that makes sense!

 

[REK Knives]

I may not have seen it in your pictures, but here’s something that helped me-did you relieve the inside of the scale or the scale side of the lock bar for the amount that the detent ball is proud?

If your detent ball is sticking out (towards the blade), say .020 (just using round numbers), and you’ve got a washer of .010, then at least .010 of material has to be removed from the other side of the lock bar or the inside of the scale. If you don’t, then the scale gets screwed on to the liner and pushes the detent up against the blade (unlike your finger that gives a little). This gives you more friction and drag than you want when opening/closing. When the blade is closed, the detent ball seats in the hole you’ve put in the blade-no problem. It’s when you’re opening or closing it that the excess thickness caused by the ball can cause problems. Taking .012 or so off the inside of the scale where the lock bar is let’s the blade push the bar out enough as it’s opening so it doesn’t bind.

This may absolutely not be the issue you’ve got going-just thought I’d share just in case. Hopefully the explanation makes some kind of sense . Good luck and hope you get it figured out. The fine tuning can drive a guy nuts on folders.


Jeremy

I'd put my money on this answer... Exactly what I was going to say. All you have to do to check is close the blade part way (so the detent ball is over the tang) then push the lock bar towards the scale and see if you can create a gap between the ball and the tang.

What's happening is you are getting detent drag from not enough clearance.

 

[blkspade99]

I'd put my money on this answer... Exactly what I was going to say. All you have to do to check is close the blade part way (so the detent ball is over the tang) then push the lock bar towards the scale and see if you can create a gap between the ball and the tang.

What's happening is you are getting detent drag from not enough clearance.

Just to let everyone know, this was the answer. It moves flawless now. I milled out a tiny relief around the lock to account for the detent.