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Mechanics of DA OTF autos
- Thread starter Dijos
- Start date
- Joined
- Jun 2, 2003
- Messages
- 354
You push the button away from you to make the blade go out, push the button toward you to make the blade go in.
Www.videoknife.com is an awesome site, its got small videos of any OTF you want to see in action. Download a few and I guarantee youll get how it all works. Also there is an auto forum which has really good info in it.
Www.videoknife.com is an awesome site, its got small videos of any OTF you want to see in action. Download a few and I guarantee youll get how it all works. Also there is an auto forum which has really good info in it.
Gollnick
Musical Director
- Joined
- Mar 22, 1999
- Messages
- 29,258
From a pure physics point of view, there must be energy stored in the knife that, when released, does the work of pushing the blade out. Obviously, that energy is stored in a spring. This is not unlike most any automatic knife. The question is, how do you get the energy in?
If you've used one of Microtech (or other) conventional OTF autos, for example, you know that to close the knife, you pull out on a mechanism usually called a "recharge lever" (though it's not a lever in the physics sense). When you pull out and then push back that mechanism, you're doing work. Part of that work is to pull the blade back in. Part of it is to compress spring, to store energy, which will later be used to move the blade forward again.
With a DA auto, you do work when you move some mechanism, typically when you pull back on a sliding button. Some of that energy pulls the blade back and some of it is stored in a spring. Obviously, no mechanism can be 100% efficient. When you use one of these knives, you'll notice that pulling back on that slide is actually pretty hard. I've seen people with weaker hands, some women, elderly, etc., unable to get that slide to pull back with just one their thumb.
If you've used one of Microtech (or other) conventional OTF autos, for example, you know that to close the knife, you pull out on a mechanism usually called a "recharge lever" (though it's not a lever in the physics sense). When you pull out and then push back that mechanism, you're doing work. Part of that work is to pull the blade back in. Part of it is to compress spring, to store energy, which will later be used to move the blade forward again.
With a DA auto, you do work when you move some mechanism, typically when you pull back on a sliding button. Some of that energy pulls the blade back and some of it is stored in a spring. Obviously, no mechanism can be 100% efficient. When you use one of these knives, you'll notice that pulling back on that slide is actually pretty hard. I've seen people with weaker hands, some women, elderly, etc., unable to get that slide to pull back with just one their thumb.
- Joined
- Feb 3, 2001
- Messages
- 32,359
If someone doesn't do it first I'll take pics of a OTF and a DA Folder and post them here, forgive me for using cheap knives for the pics, OTF(EdgeCo NATO), and DA Folder Knock Off of a S&W M-16/14?).
I'll post them later.
I'll post them later.
I just bought a MT Makora Ex. at a recent comp. and asked them how it worked and what happens if the spring breaks.
The way it was explained to me is that there are two springs. One handles the "out" motion and the other spring the return. The effort required to deploy and retract the blade is the compression of the spring. It also acts as a soft safety which keeps the thing from accidentally shooting out in your pocket/pants.
When asked abt the reliability, they told me that if a spring breaks - say the "out spring"- you'll be able to flick the blade out. If the return spring breaks, the blade will shoot out, but you won't be able to get in back in unless you push the blade on something hard - kinda like an ASP baton. But who wants to do that with a $400 knife.
They told me they just had one fail recently after 10,000+ uses (return spring). A nice feature of this design is that the springs are always at rest until the lever is used. I found this out after asking them if it was best to store the knife with the blade out. Evidently with this design it don't matta
The way it was explained to me is that there are two springs. One handles the "out" motion and the other spring the return. The effort required to deploy and retract the blade is the compression of the spring. It also acts as a soft safety which keeps the thing from accidentally shooting out in your pocket/pants.
When asked abt the reliability, they told me that if a spring breaks - say the "out spring"- you'll be able to flick the blade out. If the return spring breaks, the blade will shoot out, but you won't be able to get in back in unless you push the blade on something hard - kinda like an ASP baton. But who wants to do that with a $400 knife.
They told me they just had one fail recently after 10,000+ uses (return spring). A nice feature of this design is that the springs are always at rest until the lever is used. I found this out after asking them if it was best to store the knife with the blade out. Evidently with this design it don't matta
- Joined
- Apr 29, 2008
- Messages
- 1
As far as D/A OTFs go, the Infidel is one of the most reliable. The slightly longer slide travel results by not having to put as much force behind it. As far as a spring breaking? Microtecs usually last 15,000 to 20,000 fires, while the BM was tested to 60,000+ fires, and still didn't have any failures. Just one more example why Benchmade is the #1 knife manufacturer.
i have never heard this quoted before, according to whom??
personally, i prefer microtech OTF's to BM's,
The two springs are not independant of each other. There is not an open and close one, they both work in the same direction. You put the tension on the spring when you push the slide button forward or back to open or close the knife. There is a sliding plate that releases a retention spring pin that holds the blade open or closed (one at the top and one at the bottom). Pretty simply, and invented by the Italians in the early 1960s.