Kydex Sheath Tutorial

[ANDYLASER]

Has anyone done one? Or would somebody like to do one?
I need to know how its done, using a hot air gun and a hammer. Well, not quite that basic, but almost

[ZDP-189]

I have just done a kydex sheath. A tutorial would be easy.

[Ropeman]

I have just done a kydex sheath. A tutorial would be easy.

OOH yes please Zed

[ZDP-189]

OK. In the next day or two, I'll sheath a new knife and do a tutorial to boot.

[ANDYLASER]

Thank You Zed.

[MotorbikeMan]

Cool :d

[twisty]

This is one at knife network that was made by Jens Anso. Good stuff.

ANSO KYDEX TUTORIAL

Cheers,

Trenton

[ZDP-189]

Standby for mine later today.

[ZDP-189]

Sheath and knife are done and the pics taken, but I'm too wiped out after the combined debacle of the fire and the KITH knife fracture to post anything as enthusiatic as this write up. Tomorrow... then.

[ANDYLASER]

FIRE!

[ZDP-189]

OK, first things first. This is not going to be an ideal tutorial, suitable for the Tutorial Archives, because (1) I have limited skills and experience, and (2) the client called 80% through the job to ask to have the knife totally refurbished and that broke up the flow of the sheath tutorial. Rather, I recommend we treat it as a discussion point.

Background and Brief

The client is a friend of a friend. Armed with a book on sharpening, and a decent jigged system, these buddies began to start putting awesomely keen edges on their kitchen cutlery. The trouble was that living on yachts, and with cramped and rocking galleys, they needed ways to secure their knives where they would not knock together and chip the edge, pose a safety hazard, or clutter the place up.

In the space of a few days, I ended up making 5 or six sheaths in Kydex and Concealex, which surpassed all of my prior experience! This sheath started out as the first of the batch and ended up as the last finished.

In the meantime, at the client's request I reground and polished the blade and bolster, stripped the existing handle, replaced it in contoured cocobollo slabs, pinned with nickel silver cutlery rivets and generally tarted it up.

Remaking a sheath to fit a different knife is never a smart move, but thanks to Kydex's ability to be resoftened and reformed without complaint, I didn't waste my efforts or the material.

[ZDP-189]

Equipment and Materials

• Knife (for moulding)
• A sheet of Kydex (or Concealex, the techniques are the same)
• Jigsaw (or coping saw, scroll saw, band saw, just not a hacksaw)
• Heat gun (much better than an oven)
• Kydex press (1" neoprene with folding plywood or metal sides)
• Big vice (holds the clamp, closes quickly and exerts a lot of pressure)
• Large clamp (to press the blade end of the Kydex)
• Small clamps (for testing rivet position)
• Masking tape (for layout and heat masking)
• Marker pen (for layout)
• Drill press (not shown)
• Ball peen hammer and eyelet setter (you can use plier-setters)
• Eyelets (not shown; use 1/4" dia for .090 and 3/16" for .060)
• Brass black and brush (black enamel works better)
• Sander or abrasives (not shown; for shaping, bevelling and smoothing edges)
• Leather or aluminium shapes (not shown; for moulding clips)

[ZDP-189]

Marking out and Cutting



Select a suitable sheet of Kydex.

I bought my Kydex from PS_Bond, who I think still has stocks or the premium stuff. I prefer to use .090 for sheaths, and especially loops, because it is more substantial, structurally stronger, and the edges round better. I used .060 here, because the knife was large, the intended duty light, and the budget tight.

Get or cut a piece of suitable size, because it is easier to cut around than a big sheet.



Mark out the Kydex on the smooth reverse side, where marks are less likely to show. Always bear in mind whether it will be a left or right-handed sheath and which side the loop should go. If you mess up the direction, all is not lost; just cut the loop off and once formed, you can screw on a separate belt loop and pretend that's what you intended all along.

It is easier to mark out on masking tape, because it's a whole lot easier to see your lines on paper than on kydex. Don't scribe, because you can't erase mistakes - the scratch is there forever.

I use the blade as a template. I draw the position of the blade spine down first, and then offset the blade to the side. If you are making a two-sheet sheath like the one in Anso's tutorial, you still need to leave allowances for the handle's thickness.



Always mark out with plenty of surplus. Remember:

• Kydex can be cut off, but not put back if it's trimmed too tight
• Kydex and Concealex shrinks a little (Concealex more) when heated
• You need to leave more room for eyelets than you would if you were stitching
• Any error in placement when you fold the side (or match two-piece sides) will be trimmed off to the lowest common demoninator/ narrowest side

i.e., Leave plenty of spare at the sides.

This template is only very rough and I ended up varying from the design quite a bit. Unless you are experienced, you will find the process more of an art, a finesse, than a science and there will be a lot of reheating, squishing and trimming later in the process.



Here I'm illustrating the cutting with a jigsaw. In reality, the jigsaw isn't ideal, because the Kydex has a tendency to vibrate up and down. A bandsaw or a fretsaw, or scrollsaw works better.

Later, after forming, I do a lot of trimming on the disc sander and with files, so you just need to get the rough shape at this point.

[ZDP-189]

Heating and Moulding the Kydex

Before this batch, I had more failed attempts than successful sheaths, because I messed up the heating part. I slavishly followed the instructions of sheath kit sellers and experienced makers, with regards to oven temperature and heating time, and ended up cooking too little or too much. Sometimes, I'd watch my material give off smoke and curl into a shrunken roll, halfway into the heating cycle.

I only discovered the use of a heat gun by accident, trying to save a complete abortion of a sheath (the Spyderco neck sheath). The heat gun is actually ideal.

All you do is wave the heat gun over the Kydex till it softens. It's as simple as that. Thick or thin, Kydex or Concealex, that's all there is to it. No temperatures to watch, not times to follow. Just watch the material's bending.



This (pictured) isn't the best way to do it either! I place the Kydex on the neoprene side of the press, because the neoprene absorbs some of the heat and cools the kydex a bit more slowly. This way, the Kydex forms more precisely around the knife and the edge of the bit alongside the blade is straighter.



How do you tell when the kydex is at the right temperature? Independently of Anso, who uses the same terminology, I discovered that the bendiness of "wet leather" is an ideal indication. He's spot on.

You don't want to heat it too much, just enough to get it floppy. Experiment on an off-cut if you must.

What I do is start at one end, and sweep along in a zig-zag pattern, not stopping on one spot for too long to avoid burning. As I work the softened area up the sheet, I occasionally sweep back over the bit I've done to keep it hot. Hot Kydex will be uncomfortable to hold, but not scalding hot. I weat the gloves to protect my hands from the heat gun blast, which will cheerfully strip paint, let alone skin.



Bending Kydex is a lot like wet forming leather, but it cools much faster than leather dries, hence you have to adapt your methodology a bit.

On fold-over sheaths, I find it is easier to fold first, then re-heat, slip the knife in and mould. I fold by heating the Kydex in the middle, bending it in the "V" of the press with a ruler, and allowing it to cool.

If you don't do this, it won't be so simple to get the sides to match up at the edge.



When you're ready for the moulding, make sure all your clamps are to hand, because the Kydex should be right on the cooling point and will start to harden fairly quickly (seconds or a minute) once the heat comes off.

Stick the knife and Kydex in the crook of the V and clamp tight and quick!

I put the most pressure on the handle side, using the bench vice. I'm not sure this is right, however. Maybe putting more pressure on the blade would give it more definition there and the maybe the handle bit doesn't need it. Well, if I had a more rigid press backing using metal, rather than plywood, it wouldn't be an issue.

I leave the Kydex to cool in the press for a few minutes. It probably doesn't need so long, but there's no great advantage to taking it out quickly.



Here I have shielded the handle. This isn't necessary, and if anything reduces the moulding definition.

The press has still left good relief around the handle and blade. One thing that needs correction is the spine needs more flattening.



A good feature is that Kydex can be repeatedly reshaped. You can melt just a certain section by masking off with loose masking tape and using a heat gun.

It is always more accurate to use a press, but fingers can be used too. Fingers don't seem to work so well on Concealex, because I feel Concealex gets supple at a higher temperature and is more likely to leave impressions of your fingerprints in the plastic.

[ZDP-189]

Final Shaping and Riveting

Before bending the key features, I sanded and filed the parts to shape and applied the eyelets. Obviously, if you are making a bent-over belt loop that is attached at the bottom with an eyelet, it's essential to do that before you put the rest of the eyelets in.

I drill eyelet holes on a press, with a slow drill and supporting the workpiece on a bit of off-cut wood. Yes, you can use special wood drills, but a bit of flash round the edge of the eyelet won't ruin the piece, as long as you file it off before you fit the eyelets.

I like to drill the holes for a tight fit around the eyelet, and tap the eyelet in by placint it on a sheet of leather and tapping the overlying Kydex with a ball-peen hammer, till the eyelet comes up flush with the rim of the hole. Then I press down around the hole so the eyelet protrudes.

Tips:

• Make sure your eyelets are the correct length for the thickness of the Kydex
• A proper eyelet setter will save a lot of grief
• Plier-type setters are handy, but their reach is limited
• You will probably take the paint off the peened side of the eyelet during setting. I find that black enamel paint works better than brass black in restoring the finish.

Positioning is important. The purpose of the eyelets is to hold the sheath together at the lip to keep the knife in, to prevent the blade slipping out the side and sometimes to provide a place to screw the belt clip on or tie a lanyard.

Therefore, the eyelet at the mouth must be close enough to the moulding round the guard to grip it, but far enough to let it out. By putting a clamp at the place that you plan to site the eyelet, you can test the effect of the positioning.

I also put eyelets at the tip and at equidistant points along the edge, close enough to prevent the blade tip from slipping through when you draw or re-sheath it.

If you have to match the eyelet position to fit a Tec-Lok belt clip, you can use a jig, but so far, I have just used the clip itself as the jig.


Clips and Lips



I formed the clip around a piece of thick sole leather, but cool aluminium, pre-filed to shape would be best. As you can see, it's not precisely straight done without a former. The bottom of the clip is not attached, because I want the sheath to be able to be slipped on and off the belt without the user's unbuckling his belt.

The lip was also spot heated and bent out a bit.

Safety is important. It doesn't show in the pictures, but I like to leave a bit of the inside of the back showing, by grinding the front of the sheath lower than the back. This makes it easier to get the tip in the mouth and forms a kind of landing ramp that reduces the risk of the user's stabbing himself on resheathing. Also consider how the user may hold the sheath and avoid shaping the sheath in a way that would make it likely for him to cut his hand.

There's a lot of trimming going on at this stage. Dremmel sanding drums help for doing inside curves, but I also find tinsnips work great. Ordinary scissors will also cut hot Kydex.

Bevelling

The picture above is an awful example. I'll fix it before it goes to the client. Basically, round and smooth the edge. I find a scotchbrite wheel followed by a buffer works for me.