Forming Kydex

[Bill Harsey]

This thread is about forming kydex.
I'm not sure where to start so here is the first simple thing I thought of to try and make things easier.
When one is forming kydex in a press around a blade, there has to be some relief between the blade and the Kydex or else the blade will pinch going in and out of the finished sheath.
Many years ago I was shown by Bob Terzoula how to put tape on the blade until we have something like thirty or so thousands of an inch thickness before placing the blade and handle in the press for forming the Kydex.
If your interested in thickness's and want to put the micrometer on some tape, fold one short length of tape over and then measure the thickness with the micrometer. This keeps the "mike" from sticking to the tape. Divide that reading in half and you know the thickness of each layer of the tape used.
Or just use four or five layers of good quality blue masking tape. It comes off easier. Place tape straight up and down the blade, not around.
Using a sharp hobby knife, trim the edges of the tape right next to the edge and spine of the blade. This way the tape doesn't "print" through the kydex and show on the outside.
I have never placed tape on the handle.

Handling sharp things can be hazardous to your band-aid supply!
Especially when removing tape from sharp edges. This is not theory. Work slow and with care removing tape.

[Bill Harsey]

Kydex is a thermal forming plastic used for a lot of things including interiors of commercial and private aircraft.
A heat source is handy for thermal forming kydex. I use two of them, an oven capable of holding 300 to 400 degrees F and a heat gun for doing area forming, like in belt loops or final forming the top of the sheath around a handle.
"Not too thick" cotton gloves help while picking up and working with the warm plastic.
Here is a technique used around here: use scraps of sheath leather as a thermal mask to protect areas you don't want hot when hand forming details with the heat gun. This is very useful.

[PiterM]

Good thread! I'll try to share some of my thoughts about kydex as well, sure

Let's talk about tape on the blade... yeah, that is of course very important step. Masking tape is best, I use TESA brand (popular here in EU, good quality and THICK) and I use 2 layers usually. Sometimes 3 layers (on knives made of more than 0.2" stock). One "trick" that I use is to put final tape coat with thin transparent packing tape. Masking tape is usually not glossy, so when you press hot kydex against the masking tape that creates "micro-texture" on the inner side of the sheath! For most knives it doesn't matter that much but for very fine satin finished blades YES, IT DOES. Glossy & smooth packing tape is very thin (so it doesn't change the thickness of the tape padding in fact) but it leaves the inner side of the sheath mirror-smooth. That is a trick I use on some of the knives.

BTW, these two sheaths I made yesterday and in that case (very very fine satin finish as you can see) I had to use this trick to prevent that finish from scratching.

[Smokin Joe]

I have just a quick safety tip:

Heating Kydex for too long or at too hot of a temp can cause a very toxic gas.
Rule of thumb if it starts smoking don't breath the gas!!!

I usually heat a sheet for 5-6 minutes at 300 degrees, at that heat and duration it usually comes out of the oven as pliable as a sheet of paper. Take this with a grain of salt I do not even rank as an amateur when it comes to making anything out of kydex. But I try and have done some reading on the topic.

[Trip_Wire (RIP)]

PiterM:

Nice work!

[mcarey]

First as many of you know, not all sheaths are functional.

Proper planning for intended use is where I start for our sheaths (And that is not easy to accomplish if you want versatility). We are finding that making a multi funtional sheath is no easy chore.

So give these questons some thought......

What do you want to attach to? (Pack, belt, Molle/ PALS, a combination, etc...)

What orientation? (R/Hand or L/Hand; Vertical / Horizontal / complex angle)

What type of retention do you want? (2' drop, one hand draw, secondary retention)

What hardware is available?

What is your target cost?

I would be interested in what are the basic needs that you guys want for a field / combat knife.

[mcarey]

Here is a pic of our current Spartan Sheath.

We decided to have a removable belt loop, so the user can wear it or remove it. The eyelets match all Blade Tech (Tek Locs / Molle Locs) hardware, or the user can lash with 550 cord to pack, vest or other. Also, passes an inverted 2' drop test to insure good retention. Drain hole integrated to wash it easily. Also, shaped to allow for indexing and just a thumb push to release when drawing the knife.

We tried to meet most users needs as this is for general consumption. Your thoughts?

[Bill Harsey]

Thanks for the information, great stuff.
Piter, I'm going to try the tape thing (if I hang out here long enough, might eventually learn something)

OK, first question: Why do we use Kydex?

[HOLLiS]

Yes! Thanks for the information. I saved the link from a long time ago, to buy the tools needed to do this. I hope to be able to try this. I have to wait till I am finished build some new cabinet to fit into our current remodeling project.


Hollis.

[AF Doc]

Great thread. Kydex is strong, protective, does not absorb water, can be molded to create a secure fit for a specific application. All good.

It is also noisy. When out it the woods, the sound of a pack buckle or rifle sling hitting a kydex sheath makes a distinctly unnatural sound that seems to carry for miles. (Even a stick or rock scraping a sheath can be noisy.) I like my Kydex covered in a noise dampening material (typically nylon).

Just my $0.02 (AF script)

[MasterOfMyFate]

I Google'd "kydex" and came across another material called "concealex"... Anyone heard of this? I hadn't until then. I saw it on a knife-making supply site. They had both kydex and concealex. Concealex was the more expensive, and came in thinner sheets. I checked Wikipedia to try and find some info, but came up empty.

[mcarey]

Kydex is a tradename for colored, finish grade, ABS plastic sheet.

Boltaron and Concealex are similar products that can be formed in the same manner.

[Smokin Joe]

Originally Posted by Bill Harsey

Thanks for the information, great stuff.
Piter, I'm going to try the tape thing (if I hang out here long enough, might eventually learn something)

OK, first question: Why do we use Kydex?

It is realatively cheap, easy to form, requires little (skill or equipment) to work with, and if you screw up a mold you can place it back into the oven for reshaping. So, for me it is almost ideal to work with due to my limited abilities.

[Ken Brock]

interestingly enough, I usually don't use tape on my blades

if making sheaths for another maker, it depends on the finish on the knife


kydex is pretty easy to work with and makes a good sheath material


for years I used Boltaron, but then they stopped making it available in my chosen thickness and when I called the company to talk with them, they were dicks so I switched to kydex

[Bill Harsey]

Yep, You guys got it.
Many use Kydex because it is very cut proof. All the nylon web sheaths we use for our fixed blades have kydex inserts that are screwed on at the pointy end.
This is so the edge of the blade will not cut the nylon fabric.

Kydex forms nicely to the shape of the blade even if Mr. Ken Brock always has to do things his way.
Ken, I've found I have good fit up until putting the sheath together with the final rivets then it sometimes gets too tight. This is why I use tape.
I use Cleco fasteners to test fit up my sheaths before final assembly. The Clecos are a temporary spring loaded fastener used in the sheet metal and aircraft building trades to position stuff until it is final fitted.

Another thing to consider when forming Kydex is that thin Kydex will cool much faster than thick Kydex. This means we have less time to handle the thin stuff when trying to position everything in the forming press.