Kydex sheaths...Where to start??

Motor City Mike

Well-Known Member
#1
In all honesty I have no desire to make sheaths but I'd like to include them with my knives.

I really do not want to deal with leather work. I'd rather do kydex. Seems like it'd be a little easier. Besides, I've always liked kydex with knives I bought from other makers.

So I'm looking to get pointed in the right direction to get started.

What will I need to get started?
Is there a particular thickness I should use?
Is there a supplier you use? I'd like to do one-stop shopping as opposed to multiple vendors.
Any other advice, tips or tricks?

Just looking to get all my ducks in a row before I jump in with both feet.

TIA

-Mike
 

EdCaffreyMS

Forum Owner - Moderator
#2
What you'll need:
Kydex (of course). I personally like Kydex 100 in .093" thickness.

Suppliers: Unless you're only going to produce a VERY small quantity of kydex sheaths, I'd strongly recommend buying full 4' x 8' sheets. Buying it from the knife supply outfits by the square foot will mean you'll pay 3-4X the price per square foot versus buying a full sheet. I generally buy my kydex from Port Plastics....they have a number of locations around the country, and are online.

Some type of kydex press: You can purchase one, or build a simple one. A great item to make a kydex press from is an old wood shop vise...mount it horizontally, add a couple pieces of 3/4" plywood to the max size you need, then some foam and you're set. I made my kydex press from a "hardwood floor jack" from Harbor Freight, and fabbed the structure of it. It has a ratchet system that closes/locks, and works really well.

Heat source: I have an old toaster oven in the shop that is dedicated to kydex heating. I've also heated kydex in a microwave, but it's tricky...only a couple seconds between "just right", and a puddle of plastic. :)

Hardware: In my opinion, you can't glue kydex...so any "assembly" must be mechanical.... post screws, eyelets, rivets. etc.

Kydex is not the answer to all knife sheaths! Over the years I've come to understand that certain knife designs lend themselves to kydex sheaths, while others are not good candidates for kydex at all. Knives with guards creates challenges when building a kydex sheath, as well as any design that is asymmetrical. Kydex works as a sheath because of "pinch points"..... any knife design that doesn't have a clear "pinch point" for the kydex to "grab", or any that have too large "pinch points" will cause problems with kydex sheaths.
DO NOT try to use the blade of a knife as the "pinch point" when designing a kydex sheath..... if you do so, one little grain of grit, dirt, etc. will cause terrible scratches or gouges in a blade.

I know you said you don't want to do leather....but please don't think that kydex will replace a leather sheath..... between peoples' personal preferences, and the fact that leather is a very traditional sheath for knives, there are folks who simply do not like, or will not accept a kydex sheath.
 
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Self Made Knives

Well-Known Member
#3
I'm purposely not reading Ed's comment until I'm done with mine, lol. Let's see if we agree!

So, I get my kydex from www.knifekits.com. I use the 0.080" thickness. I usually order a 12" x 24" piece and it'll last me for a few knives, expect to pay about $4/sq ft. for smaller quantities. For example, I can usually get 2 sheaths out of a 12" x 12" piece for regular sized hunters and utilities. If you buy a bigger sheet, the price goes down a little, but not drastically. I buy the basics like black in a larger piece, but stick to smaller ones for more unusual or special request colors.

Each thickness has a corresponding eyelet, so for the 0.080" you get a #8 eyelet. Eyelets are pretty cheap, like 8 or 10 cents each. I started with an el-cheapo eyelet hand setter and wasn't too thrilled with the results. Sometimes the paint would scratch, sometimes the eyelet would split, etc. After a couple of those, I got a set of eyelet dyes from Boss at USAknifemaker and holy cow! Worth it! Perfect and stress free every time.

Make your own press. A couple of thick plywood scraps and some old hinges is fine. If you order kydex from knifekits, go ahead and get a couple pieces of their molding foam, should be about $20 if remember correctly. Glue it on your plywood, works great.

For heating, I tried the toaster oven and it sucked. Now I use a large electric griddle. I think Boss has a video up somewhere showing the same thing. Works great, wife found mine at a yard sale. You'll need a heat gun too for making belt loops and tweaking pinch points and thumb ramps.

When you start with kydex, remember to put tape on the blade before pressing for clearance relief. I use 3 layers of masking taper per side and it's just about right. Kydex sheaths will scratch your finishes too, so it's not the perfect choice for every knife.

Lastly, youtube is your friend! There's a bunch of kydex how-to's out there. Ok, now I'm going to go back and read Ed's post. Good luck.
 

C Craft

Well-Known Member
#4
So I am gonna ask a question here. The stuff they use underneath auto's now days is that the same material as kydex???

I came into a big chunk that covered the underside of a car and up through the fender well!!!

The reason I ask is I discovered it can be molded! I mean they mold it for the vehicles. However I used a heat gun to heat with and there is a fine line as to heat to form and heat too much, causing a burn or run in the material!! Just curious not trying to hijack a thread!!
 

EdCaffreyMS

Forum Owner - Moderator
#5
No, it's not kydex, it's another variety of thermo-forming plastic. It's the same in many ways, but has a much wider tolerance to heat/cold than kydex. My Mrs. works for our local Ford dealership, and I asked the service mgr. what it was (AFTER I tried to change oil in her 2018 Escape..... and the entire underside of the rig was enclosed with the stuff)..... he looked it up and gave me the name, but it's like spelling with alphabet soup. :)
 

ARCustomKnives

Well-Known Member
#6
When I started out, I bought a couple feet of .060 kydex. While it does form more "tightly" or "crisply", I've really started to prefer .080 to .090. Seems more durable and gives a better snap.

Basics: like Ed said, you'll want a press to form it. You can use something like a yoga mat, or like a stiff memory or pvc foam, but polyurethane foam is probably the best. You can buy a 12x12 piece from Boss's store and cut it in half. 6x12 will press most sheath sizes. Just use some spray adhesive to put a piece of 1/2"to3/4" plywood or mdf on one side of each piece. Then you can use c-clamps, a bench vise or some other form of leverage to squeeze them together.

Heating: I've used toaster ovens, griddle plates and heat guns all with equal success. Just don't over heat.

Securing: I like eyelets the best. Siska brand that boss sells are usually pretty good, though I've had about the same results from knifekits brand eyelets. I also have dies from Boss's store as well as Knifekits "master series", and they seems to work basically the same as far as I can tell. You'll probably have the most consistent results from using an arbor press. You can also get away with pressing them in a stout bench vise, but something like a 1/2 ton arbor press is the quickest and easiest. If you shop around, you can probably find one for $40 to $50, but knifekits also sells one ready to go for about $75. A large drill press or mill quill may also be enough, though I've never tried it.

If you want to mount any clips, belt loops etc, you might want to get some Chicago screws. I usually use 1/4" eyelets to put the screws through. 3/16" eyelets are good for the rest of the sheath, or if you're only using paracord or a ball chain.
 

C Craft

Well-Known Member
#7
Thanks for the heads up Ed. I figured it had to be some different as it has that fine line between not hot enough and too hot!!
 

John Wilson

Well-Known Member
#8
Kydex is not the answer to all knife sheaths! Over the years I've come to understand that certain knife designs lend themselves to kydex sheaths, while others are not good candidates for kydex at all. Knives with guards creates challenges when building a kydex sheath, as well as any design that is asymmetrical. Kydex works as a sheath because of "pinch points"..... any knife design that doesn't have a clear "pinch point" for the kydex to "grab", or any that have too large "pinch points" will cause problems with kydex sheaths.
DO NOT try to use the blade of a knife as the "pinch point" when designing a kydex sheath..... if you do so, one little grain of grit, dirt, etc. will cause terrible scratches or gouges in a blade.

I know you said you don't want to do leather....but please don't think that kydex will replace a leather sheath..... between peoples' personal preferences, and the fact that leather is a very traditional sheath for knives, there are folks who simply do not like, or will not accept a kydex sheath.
THIS! 10000 times, THIS!

Everyone has given great advice. But it all begins and ends with this ^ ! You really need to design your knife with kydex in mind or else you'll likely find making a suitable sheath an exercise in futility.
 

John Wilson

Well-Known Member
#9
A hard lesson learned with kydex- while the kydex itself won't scratch your blade it will hold every little speck of something that will. For a long time I could not figure out why my blades were getting scratches. The culprit turned out to be how I was making the kydex sheath.

When you fold the kydex and press it, it is not going to fold and line up perfectly as you know. The typical process is then to trim it and then shape it on your grinder. Here's the rub (see what I did there?): As you sand the kydex those grits end up inside your sheath. I don't care how many times you pry it open and try to drag a towel down through there, it's not enough. It really needs to be rinsed out.

A two-piece clamshell design is nice because you can use chicago screws to hold the pieces together while you shape it and sand it. This will allow you to separate the pieces and clean them well. Once clean you can then use rivets or whatever to join the pieces permanently.

If you are making a taco-style sheath, I highly suggest that you add some layers of tape to the knife and then press the kydex. A little clearance inside when it's all said and done will keep those micro grits from scratching the knife. Again, you shouldn't be using the kydex to squeeze the blade for retention because that doesn't work, anyway. The lip of the sheath needs some feature or dip on the handle to clip into (pinch point). Those layers of tape will still allow you to get that boned-in look to show the contours of the knife/blade. If you do the two piece clamshell, then you don't need the clearance so much because you can take the halves apart and actually clean them on the inside before final assembly.
 
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BossDog

KnifeDogs.com & USAknifemaker.com Owner
#10
I'll try not to repeat the above.
Generally, 060" is used for small knives like neckers or maybe thin fillet blades, .093" thick is most typical for bigger or general use, .080" thick is good for all around use. I prefer to use .093" and .060" and rarely use .080"

If it's in your budget, look into a thermal T shirt press. You can dial in the exact temp, squeeze it to temp and it's ready. I used a large electric griddle for years and flipped it like pancakes to get to temp. It's hot enough when it is soft like cooked lasagna pasta.

The mold foam makes a difference. Try them all. It's a consumable and will have to replaced as it takes a heat set or the foam will imprint onto the kydex. 1" thick.

There are around a dozen different types of kydex. Don't be afraid to find and try the cheapest. The more expensive versions have fire retardant other other additives that don't do anything for a knife sheath.

Generally, the kydex holster guys have the skinny on this more than the knife sheath guys and it's worth watching some of their videos.

Boltaron is a trade name for a thermal mold plastic, like Kydex. It is a different composition and is usually slightly cheaper. Some guys don't like boltaron as much as kydex. They do work slightly differently when hot but when cooled is practically identical to Kydex. Boltaron tends to curl a bit and kydex tends to just hang when limp. Other than that, they will perform the same.

to clean up the edges, reverse a grinding belt with a cloth backing and use that to burnish the edge. It's fast and easy.

Get some Bradpoint dills. A regular drill will have the kydex climbing the bit and ruining your work. (It only took me about 20 times to figure that out.)

Plan on a mix of chicago screws and eyelets. The chicago screw near the throat of the sheath allows adjustment for tighter or looser knife fit.

Everyone looks for a glue or epoxy to bond the stuff instead of mechanical fasteners like eyelets. I have never seen anything work well.

Drill a very small drill hole on the back at the tip of the sheath for water to drain.
 
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Motor City Mike

Well-Known Member
#11
Thank you everyone for the replies and advice.

That's why this place is so great. Ask a question and get honest, useful answers from people willing to share their knowledge gotten through hard earned experience. Not everyone will do that. So thanks again.

I know kydex isn't the be all and end all for every situation but I think it'll work for now.

My knives are more "tactical" and I think kydex will go well with them.

Besides, I just give them away anyway. So something is better than nothing for now.

I'd like to charge something for them someday (at least recoup the cost of materials) so I'll have to deal with the whole leather sheath thing then...pretty sure the Boss sells some kind of leather sheaths. ;)
 

John Wilson

Well-Known Member
#12
Lots of people really love kydex, especially the tactical crowd. Kydex is seen as vastly superior to leather in those circles and that's what they want, both for the look and the rugged build.

Kydex is extremely useful and every maker ought to know how to use it. I make all sorts of things from it aside from sheaths.
 

EdCaffreyMS

Forum Owner - Moderator
#13
Here's a thought.....once you get decent at forming kydex, and local gun owners find out, you can make yourself a cottage industry out of building kydex holsters for the locals! ;) I built a couple of holsters for a friend at church (it's Montana....pretty much EVERYBODY carries a gun) and pretty soon it seemed like 1/2 the town was calling, asking for "concealment" holsters. I have them bring the gun to the shop, and if they'll leave it for a day....... :) I did tell one fella who wanted to stay and watch...... if you stay and watch, the price doubles!
 

Jim Levite

Well-Known Member
#15
I myself prefer boltaron in 080. I like the smooth texture look and I feel it finishes nicer. I buy full 4'x8' sheets but have it cut in 2x4 for shipping reasons.

Google COFFEEBUM PRESS. Very easy to make. Excellent press. Also join the KYDEXPRO website. TONS of info and pictures from some very talented sheath makers
 
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#16
I bought the knifekits eyelets and dies. I had a piece of thick metal that I drilled a hole to tight fit the bottom die in. The other die I chuck up in my drill press and use it to close the eyelets to each other. Works great to me and it doesn't take that much force to form it right.
 
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