New lock mechanism for folder knive

[Natlek]

Just saw this. It's a great idea. Got it from the first scribble. Essentially mimicking a keylock with pins. Only tinkering would be how to achieve flawless ball drop when released. Either with a spring or geometrical form in the blade to force them down when unlocked and turned. Three point contact for strength while the stop pin is a safety just in case. Another issue would be securing the button not to engage when working. A small lever would do just fine. When I get some free time I'll CAD it to see possibilities, curiosity sake.

Thanks
I improvised a little today to try this with two balls , the balls are 3 millimeters Dia. . When I *remove* piston that shim /blade/ push them inside *pivot * I just need to turn it . It will work flawlessly I'm sure . Even with one ball, it locked perfectly without any play .
About the button , it can be a little deeper into the frame . The forces acting on the pivot through the blade and rollers are vertical, they can't *move* piston on side so the rollers can be very close to the transition where the thinner part of *piston* begins ....that mean short movement of button ? If I explained well what I mean

I think that rollers /say 4mm Dia. / need to be IN blade just 1 - 1.5 mm. no need for more . That way blade would push them down when button was pressed .
Tomorrow I will try with four balls, I can easy try that in my shop. If it works properly, I will visit a friend to do it properly on Lathe and mill......................

 

[JoeBusic]

My take, a quicky. I like the idea very much.

 

[Natlek]

My take, a quicky. I like the idea very much.View attachment 2217957
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I like it But little complicated to do ?
I think with rollers it is easier to make one for try . The more I think about this, the more I think that this will work almost in the same way as one-way bearings.
We have piston with say 8mm Dia . and rollers are 3mm Dia and they are 2mm In pivot and 1 mm IN blade . Blade cannot be turned under any circumstances , something /pivot/will break before that..............
In essence, when we push the rollers into the blade, we create a *No WAY* bearing ??

 

[JoeBusic]

I like it But little complicated to do ?
I think with rollers it is easier to make one for try . The more I think about this, the more I think that this will work almost in the same way as one-way bearings.
We have piston with say 8mm Dia . and rollers are 3mm Dia and they are 2mm In pivot and 1 mm IN blade . Blade cannot be turned under any circumstances , something /pivot/will break before that..............

Complex doesn't freighten me.
But the original idea with balls is the simplest and easiest to make. It should work just fine. Easy to add more balls for strength. 10 or more.

 

[Natlek]

Complex doesn't freighten me.
But the original idea with balls is the simplest and easiest to make. It should work just fine. Easy to add more balls for strength. 10 or more.

More balls would will weaken pivot . nhobo is right about the forces acting on the pivot . I would make with 4 balls this days one knife .Next one will be with rollers with help of my friend machines of course , I can t do that in my shop . The contact point on Rollers with pin and blade will be much larger, less chance of wear.
Now ............... sit down before you read this
For some project /long story/ we made a very miniature electromagnet with a friend. I think it would fit in this. the first electric knife .On/off

 

[JoeBusic]

More balls would will weaken pivot . nhobo is right about the forces acting on the pivot . I would make with 4 balls this days one knife .Next one will be with rollers with help of my friend machines of course , I can t do that in my shop . The contact point on Rollers with pin and blade will be much larger, less chance of wear.
Now ............... sit down before you read this
For some project /long story/ we made a very miniature electromagnet with a friend. I think it would fit in this. the first electric knife .On/off

Everything can be stronger with correct material choice. Premium steels with high compression strength and high strength balls make things better.

 

[Natlek]

The balls/rollers must be an even number like 2 - 4 or 6 so that the knife could remain locked in the closed position. Balls must have same or smaller Dia. of blade thickness .
Also bronze/teflon or whatever is used as shims will cover that part and dust can't get inside..
And I can t do this in my shop . I will use the right.. *Call a friend*

Just one more thing , if someone, anyone, thinks this is a good solution, feel free to try it. Or if someone has an idea to further improve this.......do that

 

[Diemaker]

While this is an interesting design I think it has a couple of problems in the real world. The issue of lock play is quite valid. You will need some clearance in the sleeve so the balls move freely. I think .001" is a minimum as there would be too much drag with any less for the balls to release smoothly. Then you will have manufacturing tolerances so say +/-.0003" on size with positional being +/-.0005". Both of these are tighter than most shops will be comfortable with in annealed steel, in hardend you will have fewer shops and a much higher price. Yes, good carbide tools will cut it fine but since this isn't a one-off deal you will have to worry about wear and deflection, both of which will be a significant problem past 10-50 parts due to the tight tolerances in hardened steel. You will have to finish them once hardened due to the tight tolerances. This is all using balls, which would make it much easier to make. All said I don't see how you can make this work, at least not well.

Cylinders will require more travel of the plunger to disengage so that is a major concern. The other major issue with cylinders is you will need rectangular windows in the sleeve for them to fit into, which is much harder to maintain your size tolerance than holes. You may also need square corners so the ends of the windows hold the cylinders in place, oops, deal killer. Now you will have to EDM them which isn't viable for many reasons, better stick to balls. There are other problems with cylinders but no need to go further.

 

[Natlek]

While this is an interesting design I think it has a couple of problems in the real world. The issue of lock play is quite valid. You will need some clearance in the sleeve so the balls move freely. I think .001" is a minimum as there would be too much drag with any less for the balls to release smoothly. Then you will have manufacturing tolerances so say +/-.0003" on size with positional being +/-.0005". Both of these are tighter than most shops will be comfortable with in annealed steel, in hardend you will have fewer shops and a much higher price. Yes, good carbide tools will cut it fine but since this isn't a one-off deal you will have to worry about wear and deflection, both of which will be a significant problem past 10-50 parts due to the tight tolerances in hardened steel. You will have to finish them once hardened due to the tight tolerances. This is all using balls, which would make it much easier to make. All said I don't see how you can make this work, at least not well.

Cylinders will require more travel of the plunger to disengage so that is a major concern. The other major issue with cylinders is you will need rectangular windows in the sleeve for them to fit into, which is much harder to maintain your size tolerance than holes. You may also need square corners so the ends of the windows hold the cylinders in place, oops, deal killer. Now you will have to EDM them which isn't viable for many reasons, better stick to balls. There are other problems with cylinders but no need to go further.

Lock play was not issue , of center stop pin will solve that . I'm thinking about how to do one copy . . I think that three balls and six cuts in the blade are best for now .......