Greetings
L
Liosha
!
Great news! With a bit of planning you can make
any shape of knife fit snugly into Kydex!
You just have to remember a few things:
First the disclaimer:
1) Kydex is soft and won't scratch your knife,
2) Well used and carried sheaths (kydex, leather, Boltaron, etc) inevitable attract dust which
will will scratch your knife,
3) You can mitigate these effect through design, but cannot guarantee a perpetually scratch free knife even with the best possible design, unless the knife literally never gets taken out and used.
Now the method I use for a guardless knife:
Let's take the EDChef for example. It has no guard for the Kydex to grab onto. If I mold the sheath directly onto the blade as I used to, the liability to scratches is high, as the retention relies heavily on friction. Here are two older examples belong to a friend of mine:
Last year or so I changed the design of the handle. Now I make the sheath using a significantly high amount of padding taped to the blade during molding, as well as a strip of material the extend from the heel of the blade back an inch or two, all the way up to the underside of the handle. What this does is ensures there is enough of a channel for the blade to insert into the sheath without rubbing the Kydex.
The new design no longer uses friction either. Which might sound counterintuitive at first. Yet they actually have snap retention because of a small indent that I put at the front of the handle. Here is an example on another friend's knife:
Now the question of blade shape. I know that khukuris, for example, or karambits, are sometimes thought of as difficult to make Kydex sheaths for. And I certainly felt that way for some time. They are still a bit of a pain, but now I have a strategy. Some makers use open backed sheaths, but I have never liked those and don't do them. With the exception of symmetrical, or near symmetrical blades like daggers and some swords, I taco everything, because my philosophy is one of minimalism, in the sense that (usually) the slimmer I can make a sheath profile, the better, whether it's for a neck knife like my Bitty Bitey Baby Birdie,
or a gnarly monstrosity like the Flicker.
The method I use for a weird blade shape:
So to do a taco sheath for the Flicker, for example, I cut some foam material of appropriate thickness such that it would cover not only the blade, but also create a straight line covering recurved portion, also ensuring that this foam was at least as wide as the widest part of the blade, which accounted for a slight sip below the bottom of the guard. That was there is enough clearance for the who knife blade to get into the sheath without bumping into eyelets, or gnashing up the mouth of the sheath. Then I painters' taped that into place on the blade.
Once the Kydex (well, actually I used Boltaron) was to the right level of softness (not too hot for one like this, because here, too much definition is actually a detrimement, as it will squeeze to tight at the top - this part you just have to get a feel for), I folded it over the spine of the knife, making a straight line for the knife to follow into and out of the sheath.
The knife goes into the sheath with a satisfying click and good retention, but comes out with ease.
This is just my way, at this time. Others will have other ways. But either way, definitely don't let sheath design deter you from a gnarly knife design, as whatever you can think up, you can also put into some pants and take out for a walk.