Lavan said:
I'll take disk as it being mounted on the top of the blade gives the largest radius from the pivot and therefore, easiest open.
Well, depending one where on the blade the disc is mounted, it might not be any more radius than a stud. What you *do* get, though, is maximum clearance between the opener and the handle, which is a great boon to those with large thumbs or limited mobility.
OK, so, MHO...
All three (stud, disc, hole) can be implemented well, or poorly. Done right, all three are effective. Done poorly, well... nail nicks start to look good!
My top choice: I'm actually a big fan of the
disc, despite not owning many knives that use 'em; the only one in my EDC rotation is a CRKT Crawford Falcon. (Well, and a CRKT Large Tighe Tac, which is actually square, but the same basic idea.) Don't have a BM Stryker, it's one of the few major Benchmades that leaves me cold. Wonder why they aren't more commonly used?
Advantages:
- Ambidextrous by design. I'm not a lefty, but on many knives I find it easier to flick them open with the index finger, rather than the thumb. Yeah, I'm weird like that.
- Excellent clearance from handles. See above. Beside easing blade deployment, it's also less likely to get in the way when sharpening, unlike some stud designs.
- Low profile, compared to a stud. (True disc only, the Tighe Tac doesn't count.) A rounded disc is highly unlikely to snag on your pocket or sheath, even if properly knurled for traction.
- User comfort. Even knurled, a disc offers a relatively large, round surface to the thumb (or finger), or if you prefer, a simple flat surface on the underside. A badly-designed one could have sharp edges, of course, but I've never seen one like that.
Disadvantages:
- Mechanically weak by design. Every implementation I've seen is attached to the blade by a screw through the disc, into a threaded hole in the edge of the blade spine. Since that little screw is the only thing holding the disc in place, it can't be nearly as strong as a stud that fits into a hole through the blade; the screw would tear out under a tiny fraction of the force required to either shear a stud, or the blade spine! (Of course, this is theoretical; I've never heard of a stud or disc actually failing in the Real World.)
- Only practical for thick blades. The thinner the blade stock, the smaller the screw. When you get down to 1/10" stock, you're talkin' watchmaker screws. (I'd like to see one dovetailed into the spine, with the screw only for lateral security. Seems like it could be much stronger.)
Then there's the
thumb hole. Mechanically about a simple as you can get. I like simplicity.
There are several variations to consider: round (Spyderco, Blackwood) vs. oval (some Benchmade) vs. oblong (Strider, Swamp Rat) vs. odd shaped (Byrd), with square or bevelled or rounded edges.
Advantages:
- Ease of manufacture. No additional parts, no screws, no knurling or checkering, you just drill / blank / cut a hole in the blade blank.
- Ambidextrous by design. See above.
- Works with any blade thickness.
- Lowest profile. Nothing to snag on pockets, sheaths, clothing, gear, etc., when drawing, sheathing, sharpening, or in use.
- Mechanically strong. The only way for it to fail is for the spine of the blade to tear out. Not bloody likely.
- User comfort. Even the sharp-edged holes used by Spyderco are surprisingly easy on the thumb or finger, although those people who use their nails instead of the fleshy part of their digit may disagree. Other manufacturers bevel or round the edges for additional comfort, at the expense of some security. The relatively large contact area allows you to apply significant force without discomfort.
Disadvantages:
- Weakens the blade in lateral stress. Face it, when you cut a large chunk out of the blade, it's not as strong anymore. Of course, if you don't make a habit of applying large lateral stresses to the blade (i.e., prying), this may not be an issue. This can be somewhat ameliorated by the designer's choice of blade profile; hence the "hump" in most Spyderco blade profiles.
- Proprietary. Well, the best ones are, at least: Spyderco has a trademark on that sharp-edged round hole, which is widely regarded as the ideal implementation of the concept. The round shape allows the thumb or finger to rotate within it freely, and the sharp edges make for very positive traction. Sure, you can get around Sal Glesser's TM by using another shape, or bevelling the edge; but then you also sacrifice some of the advantages of the design.
And then, there's the
thumb stud. Implemented correctly, it's as good as the best holes or discs; poorly implemented, it's a frustrating pain. There are endless variations: smooth, stepped or knurled; cylindrical, conical or angled; long or short; wide or narrow.
In my experience, the best ones are ambidextrous; not so high as to snag, either open or closed; positioned far enough from the handles to allow easy access; textured enough to keep the thumb from slipping off, but not so much as to tear up the skin; and either rounded, wider than normal or cut with an angle, to provide a wider contact area, for comfort.
The worst are either too small or short to allow much contact, or so long as to snag, or interfere with slicing or sharpening; pointed or coarsely textured sufficiently to cause pain to the opening digit; and/or mounted to one side of the blade only, limiting user choice in opening options.
Advantages:
- Fairly simple to manufacture. While some knifemakers craft their own studs, there are several "standard" ones available in bulk; the knifemaker needs only to drill an appropriate hole, and screw the stud into place.
- Mechanically strong. The stud is held in place by the surrounding blade stock; highly unlikely to fail in any use I can think of!
Disadvantages:
- Can get in the way. Especially if too long, or placed to far forward on the blade, they can snag in the work being cut, or interfere with a sharpener. Even with the blade closed, a too-long thumb stud can catch on pockets, sheaths or other gear.
- Can be uncomfortable and/or insecure. See above; the really bad designs can be downright painful to use. Even the vaunted Sebenza has a thumb stud that's pointed enough to be painful, while also too rounded to prevent slipping, according to some users.
- All too often RH-only. And since the one-sided ones generally use a countersunk screw on the "off" side, they're not reversible for lefties (or us forefinger-openers). I mean, c'mon guys, a proper ambi stud would cost an extra, what, $0.20 per?? Sheesh.
. Second would be the hole and them the disc. I feel the disc for some reason makes the knife look a little cheap...dont know why...it just does to me. I am also a big fan of the flipper but their dont seem to be many made with it, which is a shame...
