Noob question: What makes a knife open smoothly?

F

foofie

Joined
Sep 25, 2011
Messages
958
Just wondering - have some knives I love because they open smoothly and easily (skyline, 940)
Others seem to take much more effort. Loosening the pivot screw just makes them wobble.

Is it the washers (too simple, right)? The design (my blur opens well, the leek not so much, but the design is pretty close I think)? Quality control?
Or do some people like gritty/tight openers? :barf:


If you want to sell me a knife, just tell me it opens smooth as butter.
 
Although washers are important, once you start talking about knives with high quality, well machined washers they become less important over all.

In my experience the smoothness of a knife depends more on how the lock system engages the blade as the knife opens. Liner locks and frame locks, for example, push against the side of the blade while opening and closing the knife. The smoothness of the knife is going to depend on how smooth the path that the detent ball takes across the blade is--newer knives that have yet to break in may be gritty, as the finish on the blade itself will be gritty until the path wears smooth.

Just be aware that there is a difference between a lack of resistance, and consistent resistance.
 
Washers are definitely important--phosphor bronze, or IKBS, or something else with a ball bearing built into the washer (or the lock, for that matter) will open more easily.

Spyderco Manix 2 opens really well, because it uses a ball bearing in the lock. HK14650 flies open as if it's assisted as well. There are a bunch out there.
 
The IKBS is very smooth, too. I don't know how well it works after accumulating some dust, though.

I can't remember having a problem with a "stiff" deployment that could not be remedied by adjusting the pivot. At least on a locking liner type knife. I don't think I've ever encountered a slipjoint or lockback that was gritty. Some require more effort to lock and unlock, but I think that's a good thing.

Kershaw does good work. Maybe try contacting them and explaining the problem?
 
Is the Leek not opening smoothly, or is it just the A/O not getting the job done? The torsion bars do wear out over time.
 
Thanks for the info. I wasn't complaining about the leek in particular - but I may have used it just a little bit over time... may look into a new torsion bar.
I was just curious why some knives open so smoothly, and others seem to take more effort - regardless of price/manufacturer.
 
A lot of it comes down to machining tolerances and the finish of the parts that contact each other. Well-polished contact surfaces + parallel, tight holes = pivot can be run looser without bladeplay = smoother operation.
 
As some have mentioned, it usually comes down to pivot tightness, lube, and mostly (I believe) the type of spring the lock uses, or even the spring on a slip-joint. -And cleanliness of the pivot in general.
 
1-Blade finish: if you have a coated blade, it needs to break in so part of the coating wears and the detent glides better over the surface. Stonewashed will open smoothly. When broken in I believe any blade should open the same independently of finish
2-Washers: different kinds might have more or less drag
3- tolerances
4- weight of the blade: I think this is huge. It took me 3 days of opening/closing my Strider SnG to feel ubber smooth (3.5 -inch blade) while my SMF (4-inch blade) was smooth from the 1st thumb flick. I attribute this to the heaviest blade (tanto 3/4 gring Vs spearpoint 3/4 grind)
5-lock bar tension. The more tension on the blade, the more force you need to overcome to open.
My smoothest knives are the Hinderer XM18 3.5 and the Strider SMF if you want to check them out... pure butta'!!!!!!
 
You must log in or register to reply here.
Back
Top