This is a quick guide that explains the basic functionality and types of OTF Knives (Out The Front Knives).

Question: What is an OTF knife?

Answer: An OTF, or Out The Front knife, is a knife which opens by propelling the blade out of the front of the handle. The blade is generally housed inside the handle (often under tension) and released by pressing a button, lever, of other mechanism. Once released the blade is pushed out the front of the knife handle by a compressed spring or other similar tension device or allowed to deploy through gravity or or by manual manipulation.

Question: Are there other names for OTF knives?

Answer: Yes, sort of. “Out the Front” is the most accurately descriptive name for a knives where the blade deploys out the front (as opposed to opening from the side). Many people still refer to these knives generically as “Angel Blades,” or “Stilettos.”

Question: Are there different kinds of OTF knives?

Answer: There are actually many different versions of OTF knives. Some are automatic, some spring assisted, other depend on gravity and a few must be manually opened. Let’s take a look at some of the more interesting models and discuss their operation!

Automatic Single Action OTF

The automatic single action OTF knife is one of the more basic OTF designs. When the blade is retracted it is under constant pressure from a compressed spring in the handle. Once the button is pushed the blade is pushed out and locks into place. To retract the blade the user must press a release button (usually the same as the firing button) and manually retract the blade into the handle where it will lock back into place. Single action OTF knives often have a safety, recessed firing button or sheath to prevent accidental firing.

Many people have the mistaken impression that these knives eject with deadly force. The spring in these knives is designed to open the blade and lock it into place, no more. If you were to accidentally open the knife into your hand you would get cut, but serious injury is actually unlikely.

Some popular models of single action automatic OTF knives: Microtech Halo, Paragon Para-X and the Protech Dark Angel

Have a look at the video below to see a single action automatic knife demo.

Automatic Double Action OTF

The automatic double action OTF knife is an impressive example of engineering. When the blade is retracted it is not under any tension. Instead spring tension is created by sliding a firing button (usually on the front or side of the knife) upward (thus creating tension on an internal spring). Once a certain threshold is achieved the blade is released and the spring tension propels the outward and it locks into place. In the open position the internal spring is also at rest. To close the knife the user slides the firing button downward (again creating spring tension on the internal spring in the opposite direction). Once a certain threshold is achieved the blade is released and the the spring tension pulls the blade inward and it locks into place. No safety is needed on a double action knife because there is no possibility of the blade accidentally deploying.

Many people have the mistaken impression that these knives eject with deadly force. The spring in these knives is designed to open the blade and lock it into place, no more. If you were to accidentally open the knife into your hand you would get cut, but serious injury is actually unlikely. Double action automatic knives open with less force than their singl action counterparts.

Some popular models of double action automatic OTF knives: Microtech Ultratech, Benchmade Infidel, Piranha Excalibur.

Have a look at the video below to see a double action automatic knife demo.

Spring Assisted Single Action OTF

The spring assisted single action OTF knife is a new innovation on an older design. When the blade is retracted it is under constant pressure from a compressed spring in the handle. Once the button attached to the blade is pushed part of the way out  the spring pushes the blade the rest of the way out and it locks into place. To retract the blade the user must press a release button (usually the same as the firing button) and manually retract the blade into the handle where it will lock back into place. Single action OTF knives – even spring assisted models- often have a safety, or sheath to prevent accidental firing. The key difference between an assisted OTF knife and an automatic OTF knife is that the assisted knives must be manually started and the button or lever is part of the blade, not the handle.

As with the other OTF knife designs,  people have the mistaken impression that these knives eject with deadly force. The spring in these knives is designed to open the blade and lock it into place, no more. If you were to accidentally open the knife into your hand you would get cut, but serious injury is actually unlikely.

Some popular models of single action spring assisted OTF knives: Schrade OTF & Smith & Wesson OTF

Have a look at the video below to see a single action spring assisted knife demo.

Gravity Single Action OTF

There is no spring in the gravity OTF knife. The blade is locked into the handle by a lever which creates tension against the blade to hold it in place. When the lever is released and the knife is turned upside down the blade simply falls open. The same lever created tension against the blade to hold it open. This design is very simple and was employs in serveral knives by the Germans.

Some popular models of single action gravity OTF: German Paratrooper Knife.

Manual Single Action OTF

There is no spring in a manual OTF knife. Geneally there is a sliding lever than can be used to push the blade out into place (this system is commonly found on utility knives). Other manual OTF systems push the blade up and out when the handle is opened or acted upon in some mechanical way (this system is commonly found on “paratrooper knives”).

Some popular models of single action spring assisted OTF knives: Paratrooper Knife, Smith & Wesson Powerglide.

 

Other unique OTF models:

There are several OTF models which feature a blade that automatically retracts (as opposed to opening). They operate similarly to the spring assisted single action knives, but in reverse.

Some popular models of automatic retracting OTF knives: Boker Bokermaitc, X-5 Switchback.

 

Question: Who makes the best OTF knives?

Answer: Many companies make exceptional OTF knives including Microtech Knives, Benchmade Knives, Protech Knives, and more. We’ll be compiling a list of manufacturers of OTF knives and popular models in near future. Stay tuned!

Question: How strong are OTF knives?

Answer: The strength of an OTF knife will vary by it’s build quality. More expensive brand name OTF knives have proven their reliability in extreme conditions and are incredibly durable. Because OTF knives have moving parts they are more susceptible to wear than fixed blades (which are universally regarded as the most rugged).

Question: Who invented OTF knives?

Answer: Good question! We’ll do some research and write up an OTF History article!

Question: What kind of care is required for OTF knives?

Answer: The same care of would be required for any knife with moving parts. Periodic cleaning, lubrication, etc. Also, you have to take special care no to exert too much force on the blade via prying. OTF knives are susceptible to breakage if too much force is leveraged against the blade. We’ll be creating  “Care and Maintenance” article in the near future. Stay tuned!

Question: Can I buy an OTF knife?

Answer: Many OTF knives are automatic and therefore have federal laws and possibly state laws that apply to them. We suggest doing more research on owning an automatic knife, as not everyone is eligable. While no federal regulations apply to assisted or manual OTF knives many states still have laws pertaining to these types of knives. Once again, we suggest careful research before you purchase any of these knives. We cannot provide any legal advice regarding the purchase or use of any OTF knife, we are simply an information resource.