Kydex Sheath for a Bark River Magnum Fox River

Ink and Fish and Knives

 

Kydex is a brand of thermo-plastic that gets soft when it's heated. It's a very nice material for making knife sheaths out of, since it can be moulded to a specific knife for a custom fit, and the sheath can be designed to retain the knife securely without requiring an additional clip or strap to stop it falling out, which is a feature I really like. The knife can quickly be drawn and sheathed with one hand.

I've recently tried making a few kydex knife sheaths with pretty good results. There are much more efficient and professional ways to bend kydex, but this is the way I did it with the limited tools I have.

 

The knife I'm making a sheath for is a Bark River Magnum Fox River, a large game processing and general camp knife. Here it is in the leather sheath it's sold with:



 

 

It seems decent as far as leather sheaths go, but it's a bit bulky, awkward and rustic for my liking.

First step, I put two layers of masking tape around the blade of the knife and the handle up to where I was expecting the sheath to go. This will protect it from being scratched excessively and give the blade a little space, as you don't want the kydex gripping the blade itself.

 

Cut kydex to size. I'm using black 2mm/.08", which is pretty standard for a knife sheath, and making a taco-style rather than pancake-style. Taco meaning one sheet folded over the knife, whereas pancake is two sheets layered with the knife between. You can test-fit with a piece of paper and trim it to size to get an idea of how big the kydex needs to be. I left a good 2.5cm/1" of excess in front of the edge for riveting.

I'm not sure if anywhere local (to Australia) sells kydex, but you can order sheets of it on ebay from overseas relatively cheaply. This is half a 30x20cm/12x8" sheet, the other half I already used to make a sheath for a similar sized Bark River knife for a friend.
Next, heat the kydex. I'm doing this over a small portable butane stove, with and a cake cooling rack. A heat gun or a large electric hotplate are more typical and lessen the chance of burning the kydex, but I don't own either, so I'm using what I've got.

I'm also doing this outside so that in the event of kydex scorching I don't stink up the house with burnt plastic fumes. I just moved it constantly over the highest flame setting not more than 5cm above it. Once it's floppy like a wet cloth it's ready to be folded over the knife and pressed. You'll want to wear gloves when handling it because it's very hot, and you need to work fast as it cools down and stiffens quickly.
My press consists of two foam kneeling pads, two planks of wood, and three sheets of paper to prevent the foam sticking to the hot kydex.

A more professional press might involve thicker foam and clamps.
Hot kydex bent over the knife, layered between paper and foam and wood, I stand on it for about five minutes to form around the knife and wait for it to cool. Shoes optional.

Removed from the press, the sheath is quickly taking shape. I ended up reheating and repressing several times to get the blade positioned the way I wanted it - not too far from the spine, not too close from the spine.

I didn't get any photos of the next few steps, but I used a white conte pencil to mark off the excess I wanted to trim and where I'd drill for eyelet-rivets. I trimmed and rounded three corners with a bench grinder, marked holes 38mm apart so the sheath would be able to accommodate a Tek-Lok if I wanted, and drilled the holes with a ~6.5mm/1/4" bit.
The eyelet rivets I used are slightly bigger than necessary, but they're what I've got so they're what I used. Ideally they should be a little smaller diameter and a little longer, but they still have plenty of grip.
Once trimmed and riveted I sanded the edges of the sheath to smooth it out, and cut any burrs off the inside throat. I then reheated just the throat and bent it upwards to give bigger surface area for my thumb to push against when unsheathing the knife.

 At this stage the sheath is more or less finished. But I wasn't happy with the retention of the sheath - it was gripping the blade too much and the handle to little, and the spine area of the sheath wasn't pinched tight enough so the blade would often get wedged in there when sheathing. Kydex tends to want to return to flat sheet form when reheated so I just heated it as a whole which let it expand and loosen around the blade, then with a pair of needle-nose pliers wrapped in several layers of masking tape so as not to leave teeth marks, pinched the spine tight, and pinched in the throat area around the heel of the blade.

With the retention adjustments, I can hold the knife in the sheath upside down and shake it and it won't fall out, with a short push of the thumb the knife is released and draws freely, and there is no rattle. This is better than any kydex sheath I've paid for.
I added a spring clip with a Chicago screw and a small elastic band wound beneath the post head (in lieu of a rubber washer I'll sort out later) to eliminate rattle and hold the clip in alignment but allow for adjustment.

It's a large heavy knife, but so sheathed, it carries comfortable deep in a large pocket. I'll probably add another eyelet down from the current clip attachment so it can be moved down slightly and carry inside a belt with the throat of the sheath sitting higher.

 

Comparison with the manufacturer's leather sheath. The kydex is a lot shorter and slimmer. I could trim the excess to make it narrower, but I like it as is for the moment.

This is the fourth kydex sheath I've made and I think it's the best so far.