Detent ball sizing question!

Lyon

Lyon

Joined
Jan 11, 2009
Messages
35
Hi all,

I am making a flipper and it is almost done. I am down to the detent ball and I have a couple of questions.

All measurements are in inches.

I am using a standard .0625 detent ball. I have .010 clearance between the blade and the liner(liner lock style). When doing the math with an online calculator (http://www.1728.org/circsect.htm) it looks like a 1/32 hole in the blade will give me the correct clearance I need. As it happens I have a 1/32 tip on my #0 carbide centerdrill!

I don't have the experience to know if this will have a negative effect on the preload of the flipper or what the industry standard way of solving this problem is.

Thanks!

Matt
 
What style of flipper are you making, a liner lock vs a frame lock & bolster lock work a little differently for the depth of detent ball. Most spacing is around .020" the detent is set at .0425" or so.

The detent depth vs the size of the detent hole on the blade determines the snap in your flip. Every maker does t a little differently depending on the action they want. On your blade you should use a #54 or #53 depending on detent depth. With a .0425" depth it should be #54. Your blade gap won't matter because it's a ball on a lever arm. It's the engagement of the ball to the hole.

I use #53 because I set my detent ball higher for more snap.
 
I can't post videos on here but if you go to my ig you can check out my action videos and see what I mean
 
You are trying to figure out how large of a recess you need in the blade to engage a .0625" detent with the proper tension? If I understand correctly.

I don't make folders, but I've done a fair amount of ball detents on other things, and I think a .0312" diameter recess is going to be on the small side for engagement. I could be wrong. Here it is drawn to scale:

EwO569.png
 
Kuraki, I got .005 but yeah, that is a nice drawing :D.

Pittknife, I am making a liner lock. So if I use the smaller hole in the blade it will take less resistance to over come the detent assuming the lock bar tension is the same correct? I was hoping that it wouldn't be a significant amount.....

Also, the #53 is for the hole in the liner correct? Something like a #55 is typical in the blade correct?

I want to have a standard opening resistance to overcome the detent and I only have .010 clearance between the blade and the liner. I guess I could set it up with the bolsters and scale off then head over to the surface grinder and thin out the part of the lock bar that is being held up by the detent ball. On the previous knife I did I used a #55 for the detent hole in the blade and I used the surface grinder to take a few thou off of the detent ball to get it all to fit.

At least I can try it with the smaller hole and go bigger if I want to/need to later.

Your thoughts?

Thanks for the replies!

Matt
 
Last edited:
For a liner lock you taper the outside of the lockbar for about an inch to length. Typically what your detent height is so t can flex, don't do it to the scale.

Most folders now use a #54 on the liner and a #54 or #53 on the blade. You don't have the ball in perfect alignment with the detent hole or you will get pre-flip slack which most people hate and is an indication of bad tolerances. You use a larger hole because you are setting up for the tangent of the ball to be at the closets side of the detent edge. Your detent is .0625 a #53 is .0595 which is still smaller. But because of your detent depth it will be bigger than what the ball comes into contact.
 
Pittknife,

Thanks again. Looks like I haven't been keeping up on all the changes!

So to rephrase it. You use a bigger hole in the blade to provide a longer time pushing against the detent to provide a faster opening. It also doesn't hurt to have a bit more room for error so that the blade will be held closed properly.:rolleyes:

Just to clarify on where to taper the lock bar. I should do it on the side facing the blade?

Thanks again.

Matt
 
Lyon said:
Pittknife,

Thanks again. Looks like I haven't been keeping up on all the changes!

So to rephrase it. You use a bigger hole in the blade to provide a longer time pushing against the detent to provide a faster opening. It also doesn't hurt to have a bit more room for error so that the blade will be held closed properly.:rolleyes:

Just to clarify on where to taper the lock bar. I should do it on the side facing the blade?

Thanks again.

Matt
Click to expand...


Correct on the detent.

On the lockbar you do it to the face facing the scale.
 
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