SpyderJon said:
I can think of a reason: jurisdiction. Plainly said, an axis lock is a FINE lock, and probably one of the best out there as far as mechanics are concerned, however one can "flip" the blade out with a flick of the wrist (and a manipulation of the axis bar). This means that in jurisdictions where they are ultra knife-unfriendly, it can be considered a gravity knife.
All Axis locks have fully adjustable pivots. If your local LEOs are flip-happy, you can crank it tighter until it pushes open but doesn't flick. Which is an especially good idea if you are, say, mailing one from the USA to Canada.
BlondieAlmostEdge said:
The already-stated thinness problem for example. It seems to be impractical to produce an AXIS lock bearing knife as thin as a calypso jr, for example.
I don't own a Calypso - exactly how thin is it? The Zytel BM 530 and aluminum BM 960 are 0.93cm and 53/64 grams per the catalog - the 530 is visually thinner than my old Endura. I'll tell you it's so thin I forget when I'm carrying it. Is the Caly significantly under 9mm? Surely someone has a Caly and a 530 or 960 and can give us a visual? Or a 921 is only 1.04cm, a 770 0.99cm.
Mdarby, I own a short stack of Axis Benchmades and one SOG Arc, a 4" Pentagon (the PE 14, I think). The PE is a decent knife. In my opinion it feels less well put together than a Griptilian. Not weaker, but less precise, sloppier. The tolerances are more like a Cold Steel or CRKT than a Benchmade. Then again this is a 4" Arc Lock with full liners that used to cost about the same as a mini-Grip. (But it looks like MSRP has gone up to $105.) I'd probably rather rather have a Trident - a higher grind and you can get it in plain edge. But you can get the PE in a 5" blade.
I think the biggest advantage of the Axis over the Arc is that there are a lot more Axis knives to choose between - the Arc Lock has the PEs, the Vision tantos, the Trident, the little gents sized thing and the credit card, and that's it, and the PEs and Visions are combo only. (There were what, literally a dozen of each in plain?) And except for the single high-end Vison in ATS34, I think they're all AUS8. If there's an Arc you like the looks and materials of, based on my experience I'd say it'll be a solid performer.
Based on what I've actually held in my hands, I don't think the inexpensive (PE, Trident, Zytel Vision) Arc locks are as good as even the inexpensive Axis locks (Grips, mini-grips, 530). Which is a long way from saying I think they're bad. I've never handled one of the full-built titanium Visons, so I don't know how much better it's fitted. I certainly trust my SOG PE14, and carry it as a beater. I trust it more than I trust any liner lock.