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Minor rant: 3/32" endmill to cut lockbars?
- Thread starter brandon
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Do you have an example of a knife that does NOT have this cutout? It's cut so you CAN flex it 'unlocked'.
I'm confused....
Coop
I'm confused....
Coop
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As Coop noted, you have to have that cut to allow the lockbar flex. Some makers (the Benchmade 630 Skirmish and Kershaw Ti-ZDP Mini-Cyclone are examples) camouflage this by putting it on the inside of the knife (vice the outside) but I have heard that the outside is better for geometry reasons.
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Just grab yourself a piece of titanium about .080 or thicker by a 1/4 wide and TRY to flex it and you will answer your own rant QUICKLY.
That's not what I'm talking about. I know how they work, I have owned more than my fair share of framelocks, including about 40 different TNT's. (the standard to which I compare all others) I'm talking about the gap between the lock bar and the rest of the lock side scale.....the 3/32" GAP behind the lockbar.
The lock bar should not twist when opening....move out of the way, yes, but not twist or deflect in the process.
The lock bar should not twist when opening....move out of the way, yes, but not twist or deflect in the process.
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I'm not a folder maker but I think I can shed some light here
3/32 is the smallest slot that can be cut with an arbor mounted abrasive cutoff wheel mounted in a mill. this is one of the most common methods of cutting the long slot of a folders lock.
even water jet cutting leaves a minimum of (i believe) nearly 1/16th
3/32 is the smallest slot that can be cut with an arbor mounted abrasive cutoff wheel mounted in a mill. this is one of the most common methods of cutting the long slot of a folders lock.
even water jet cutting leaves a minimum of (i believe) nearly 1/16th
I'll also point out (from a purely mechanical engineering point of view) that the only way for a smaller gap to prevent twisting/deflection of the lockbar is if the gap is so small that the lockbar rubs against the opposite side of the gap. That sounds like really bad design/engineering/usage-experience to me.
One could argue that the 1/32"-1/16" of additional material would add stiffness, but that additional material could just as well be designed onto the outside edge of the lockbar or the lockbar cutout be moved up that distance.
One could argue that the 1/32"-1/16" of additional material would add stiffness, but that additional material could just as well be designed onto the outside edge of the lockbar or the lockbar cutout be moved up that distance.
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I use a 1/32 = 0.03125 abrasive cutoff wheel. I have thinner ones that I use on smaller knives, I don't like a huge gap from the lock cutout.
Maybe too much material has been removed from the lock relief area to ease unlocking. That would allow the lockbar to twist since that is where it is connected. I would also think that the length of the lock or the width of the lockbar might allow some twisting. The wider and shorter the lock is the stiffer it will be.
Maybe too much material has been removed from the lock relief area to ease unlocking. That would allow the lockbar to twist since that is where it is connected. I would also think that the length of the lock or the width of the lockbar might allow some twisting. The wider and shorter the lock is the stiffer it will be.
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i too use a semi thin slitting type saw
the only problem i see on a framelock witha wide slot is that it might pinch a flap a skin
now if your talking about the clearance of the inside bolster/scales so that the liner lock has abit more space to "open" thats for the ball detent when it hits the blade tang (things can bind at that point)
i still think that a good folder maker should mostly take care of that problem with the proper pivot washers and or detend press fit (there are times thta a bit of room is needed to keep fit up looking right tho )
the only problem i see on a framelock witha wide slot is that it might pinch a flap a skin
now if your talking about the clearance of the inside bolster/scales so that the liner lock has abit more space to "open" thats for the ball detent when it hits the blade tang (things can bind at that point)
i still think that a good folder maker should mostly take care of that problem with the proper pivot washers and or detend press fit (there are times thta a bit of room is needed to keep fit up looking right tho )
They do it that way because they are using some sort of mechanical device to cut the frame and lockbar and that is probably the smallest endmill that will stand up to the force.
CNC or Pantograph-Entire frame and lock are done at one time.
Not sure why this would cause a problem......of course you have to plan ahead and leave plenty of material on the lock side of the handle.
CNC or Pantograph-Entire frame and lock are done at one time.
Not sure why this would cause a problem......of course you have to plan ahead and leave plenty of material on the lock side of the handle.
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Brandon, if you're talking about the width of the slit then I'd say some like them narrow, others wide. Those in my attached pics were made with a 1/32" slit saw. I personally prefer this narrower slit. However, I have a good customer who likes them wider, so I have a slit saw that's a good deal wider. I tend to chase the slit with a 1/4" ball end mill for looks only.
As for the lock bar twisting or deflecting (bending in the middle?) I don't believe it should. Frame locks are generally made with thicker stock and there shouldn't be any flex except at the pivot point where it's been thinned down. I could see it twisting, that is rotating around it's longitudinal axis, if it's way too narrow, but I've never seen any frame locks that I thought were too narrow. It might twist if that thinned down pivoting area were too thin, and I've seen some knives I thought were too thin. It makes for a light action and a great flipper, but it's also kind of flimsy.
David
As for the lock bar twisting or deflecting (bending in the middle?) I don't believe it should. Frame locks are generally made with thicker stock and there shouldn't be any flex except at the pivot point where it's been thinned down. I could see it twisting, that is rotating around it's longitudinal axis, if it's way too narrow, but I've never seen any frame locks that I thought were too narrow. It might twist if that thinned down pivoting area were too thin, and I've seen some knives I thought were too thin. It makes for a light action and a great flipper, but it's also kind of flimsy.
David
Attachments
I cut my slots with a 1/16" endmill. The problem with trying to go smaller is that framelocks are thick, and smaller endmills simply don't offer enough length to make it through the full thickness. I wish I had $85K for a wire EDM.
However, the width of this slot really has no effect on the performance of the lockbar. If the lockbar twists, or deflects vertically, or some other thing, it's because of some other geometry that's not right. It's like using a 2 x 4 when you need a 2 x 8.
A lock is a beam, and if the designer of the knife does his job, the bar will be of the proper proportions and dimensions to react the loads applied to it during use. If the geometry is right, the load from the blade will act directly along its length (and therefore will not try to deflect the locking bar upwards or downwards).
I hope this is clear and not too technical.
However, the width of this slot really has no effect on the performance of the lockbar. If the lockbar twists, or deflects vertically, or some other thing, it's because of some other geometry that's not right. It's like using a 2 x 4 when you need a 2 x 8.
A lock is a beam, and if the designer of the knife does his job, the bar will be of the proper proportions and dimensions to react the loads applied to it during use. If the geometry is right, the load from the blade will act directly along its length (and therefore will not try to deflect the locking bar upwards or downwards).
I hope this is clear and not too technical.
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^^^ Crystal.
Coop
Coop
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This was my first framelock. The titanium is .122" thick. I used a Dremel type cut off wheel on a $60 Harbor Freight drill press. The horizontal cut was done 1/32" thick and the vertical was done with a 1/64" thick wheel.
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its funnny that you bring up how the forces load and how a well done knife spreads the load over many different areasI cut my slots with a 1/16" endmill. The problem with trying to go smaller is that framelocks are thick, and smaller endmills simply don't offer enough length to make it through the full thickness. I wish I had $85K for a wire EDM.
However, the width of this slot really has no effect on the performance of the lockbar. If the lockbar twists, or deflects vertically, or some other thing, it's because of some other geometry that's not right. It's like using a 2 x 4 when you need a 2 x 8.
A lock is a beam, and if the designer of the knife does his job, the bar will be of the proper proportions and dimensions to react the loads applied to it during use. If the geometry is right, the load from the blade will act directly along its length (and therefore will not try to deflect the locking bar upwards or downwards).
I hope this is clear and not too technical.
who thought they would ever use the geometry they learned in high school to apply forces to lock faces and bars