Question for the Kydex people

[i4Marc]

I finished a couple of large hog knives recently. Because they are going to be used outdoors and covered with blood and guts I chose Kydex for the sheaths. You can see what I'm talking about here:

http://www.bladeforums.com/forums/showthread.php/1403444-Hog-knives-finished?p=16177241#post16177241

One of the remarks I got about the sheaths was that the person commenting was not partial to all the eyelets running down the sheath. Fair enough. But I'm still very new to Kydex sheath construction. So here are my questions:

How do you assemble larger sheaths without using glue if not with eyelets? What other hardware is used?

How far apart can you space fasteners without the sheath halves losing a tight fit to each other, causing lack of rigidity and allowing debris and moisture to enter through the cracks (and looking like crap)?

If there are other considerations I have overlooked please enlighten me. Feel free to post pictures of examples.

 

[sheathmaker]

I am not a Kydex maker, but based on what I read in your linked thread and my own experience, I'd say the sheaths are very well made, attractive as kydex can be, and appear that they would function flawlessly.

Further (in my experience), you will rarely, but occasionally run into a customer who just has to be a frustrated designer. A person who really doesn't have the first clue about what is possible, and what works the best or why........but THEY THINK THEY DO.

You can try to explain to them why......but most of the time it falls on deaf ears. If your "comment" came from such a person, then just know what you did is more right than wrong (if wrong at all?)

You might get by with about half of the rivets using every other one spacing, but I still think your original design was/is flawless..

Carry on, you did good!

Paul

 

[i4Marc]

Thanks Paul. I appreciate that. I don't think the people that felt the way I mentioned are unreasonable. I don't necessarily disagree with them. I just don't know another technique yet. And to be fair, I suppose just because I consider myself artistic or having decent design sense doesn't preclude others from having their own valid or even superior design sense. I just do what I do the way that makes the best sense to me. With eyelets going all the way down the sheath it does add some functionality as far as attaching accessories like ferroceramic rods or spare paracord. But it does start to look a bit busy on the longer sheaths, especially if you like a cleaner look as I do. So, I'm still open to ideas if anyone has a clever technique.

 

[Kiah]

I'd guess the critique was towards the number of eyelets. It's really a personal taste thing as less won't make the sheath any smaller and, as you said, it gives more attachment options. You can definitely go wider apart without hurting anything if you like. Half that number should be more than adequate. You could also go foldover, you just have to plan out your pre-form cutting around that guard.

That said, I like the way those sheaths look with those knives. The eyelets kinda carry on the handle pattern if that makes sense and the trimming around the retention area is very nicely done. Only critique I could make is where the eyelets get out of line on one, but it looks like you got that sorted.

If you don't mind my asking, what did you stamp your logo with?

 

[jvin248]

How many rivets are necessary? One more than the minimum.

"Rockefeller was relentless... he observed a machine that soldered the lids on five-gallon cans of kerosene destined for export. Upon learning that each lid was sealed with 40 drops of solder, he asked, "Have you ever tried 38?" It turned out that when 38 drops were applied, a small percentage of the cans leaked. None leaked with 39, though. "'That one drop of solder', said Rockefeller,...'saved $2,500 the first year; but the export business kept on increasing after that and doubled, quadrupled--became immensely greater than it was then; and the saving has gone steadily along, one drop on each can, and has amounted since to many hundreds of thousands of dollars"' (Chernow 1998, pp. 180-81)"

Has anyone tried to quantify a 'minimum' number of rivets per inch? Or some other measurement? Before problems appear?

 

[i4Marc]

Thanks folks.

Kiah, You have an eye for detail!. Yes, I got one eyelet out of line. That was because where the kink in the edge of the sheath turns in toward the bottom, I intended to follow that kink when I drilled the holes. But I accidentally went one hole too far on the layout line I drew along the edge of the top section. No harm done though, that mistake was on my brother's sheath not mine. Hahaha. The logo was stamped with my leather stamp. I'm still trying to figure out how to get a clean stamp on there. The problem is that the molding of the sheath contours and the stamping require two different processes and heating cycles. And you know that the material has a memory. Regardless of which operation I do first, the heat from the second operation will cause the impressions or contours from the first to soften and revert the Kydex to its original state. I mold the sheath contours first then use a very careful localized heat to prepare the logo area for an impression. But the time it takes me to get the stamp positioned in my shop press and aligned perfectly perpendicular to the surface takes too long. The Kydex starts to cool and I never do get the angle just right. Like I said, I'm still experimenting with that.

 

[AVigil]

After figuring out where and how you want to attach at the top of the sheath, you can space out the eyelets a couple of inches.

Once set the blade is not going to get past them.

 

[Jens Schuetz]

Instead of eyelets you could use screws though I bet that's not what the customer had in mind

Another thing I've seen though only once is that the body side of the sheath was a flat sheet of Kydex (or other plastic) and the outward facing side was more rounded to conform to the blade and folded around the flat sheet for maybe 5 - 7 mm.

Another approach which I'm just making up (pls dont laugh) would be to groove both Kydex sides around their edges, drill many small holes through these grooves and then double stitch them together. Since Kydex is smooth and the layers may slide against each other even with a tight stitch I'd still add 3 eyelets to prevent that. Two on top and one at the bottom.
Actually first groove one side, then drill and then using the holes as a guide groove the second side so it aligns nicely.

 

[i4Marc]

Thanks guys.

Adam, have you found at all that the seam wants to open up in the longer sections between the eyelets? Does having fewer eyelets reduce rigidity in that area?

 

[mete]

You can use grommets , 1/4" hole or smaller .But 1/4"is used for fastening to equipment etc.
Use adhesive , Loctite 409 is the proper one
Use screws.Use some type of line such as stainless steel wire Use thin wire because thick wire is too stiff to handle .You could use a few grommets and something like nylon line between that.
When hunting I usually take a simple cardboard sheath so as not to messup the sheath .

 

[Vili]

... The logo was stamped with my leather stamp. I'm still trying to figure out how to get a clean stamp on there. The problem is that the molding of the sheath contours and the stamping require two different processes and heating cycles. And you know that the material has a memory. Regardless of which operation I do first, the heat from the second operation will cause the impressions or contours from the first to soften and revert the Kydex to its original state. I mold the sheath contours first then use a very careful localized heat to prepare the logo area for an impression. But the time it takes me to get the stamp positioned in my shop press and aligned perfectly perpendicular to the surface takes too long. The Kydex starts to cool and I never do get the angle just right. Like I said, I'm still experimenting with that.

Could you go into a bit more detail about your stamping process?

Have you tried using a wet cloth or towel to isolate the areas you don't want re-heating, while leaving the area you want exposed to a heat gun (http://www.bladeforums.com/forums/showthread.php/969223-DIY-kydex-leather-tutorial-the-noob-way Just ctrl-f "wet").

I also came across a pretty cool youtube video showing you how to stamp plastic that might help you out

[video=youtube;WAKRlrrs5GY]https://www.youtube.com/watch?v=WAKRlrrs5GY[/video]

One more thing, heres a PDF from Sekisui walking you through hot-stamping Kydex (http://sekisui-spi.com/assets/images/products/KYDEX%C2%AE_Sheet_Technical_Brief_151-C_-_Hot-Stamping_KYDEX%C2%AE_Thermoplastic_Sheet.pdf)

Hopefully this helps even a bit.

 

[i4Marc]

Thank you. My process is experimental. I make a rough form on which to lay the sheath half. Because of the angled surface caused by the blade bevel, the surface needs to be propped up so the surface is flat and perpendicular to the stamp. I put my leather stamp into an adapter I made for my Harbor Freight 20 ton shop press and set up the jig under the ram. I heat the local area where the stamp will go using a heat gun with a small nozzle. Quickly, I set up the sheath half on the form and crank the stamp down until it is just above the surface of the Kydex and try to align the stamp as flat on the surface as I can then crank it down to make the impression. There is too much fiddling involved this way and the Kydex looses heat too fast. Obviously the best way is to heat the stamp not the Kydex. I haven't made the decision yet to heat up my brass stamp but I think that would be the way to go.

 

[Chris Meyer]

i4Marc,
If your sheaths are truly going to covered in blood and guts, I wouldn't recommend joining the sides together permanently. I would use stainless steel Chicago screws. That way you can take the sheath apart to clean the interior when necessary. I would also use far fewer screws/rivets than you did on those Kydex sheaths you made (your knives kick ass by the way), otherwise you'd spend eternity trying to disassemble and assemble your sheaths. Alternatively, to cut down on the number of screws, you could lace paracord or leather through the holes you drill in the Kydex. (By the way, if you order screws from the link I provided, you can get them to paint the screws black before they ship them.)

Below is one of my recent Kydex sheaths. It's much smaller than the sheaths you linked to, but you can see that I spaced my screws much further apart than you did on yours. If I recall correctly, I spaced most of them 2 inches apart. They hold the sheath halves together quite well.

 

[Pavlos]

Hi i4Marc,
I'm not an expert either, but if I remember correctly, we used an eye-let about every inch or so. We used Tek-lok belt clasps, and we moved the rivets about 1/2in from blade. We used a heat gun to adjust the tension until we had a good feel for taking the knife in/out of the sheath as well. We never had an issue with the Kydex splitting or having gaps between the layers either. We produced many fixed blade Kydex Shealths that were deployed over seas for military personnel and never had complaints about our systems. I think it comes down to style and costs... how many sheaths do you make in a week and how many rivets do you use? We would do 500+ a week so putting in a lot of rivets could get costly I guess.

Paul,

BTW, I really like that knife in your link. Wish I had cash funds!