Kydex or Aluminum Liner Sheath Material?

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gudspelr

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Jul 1, 2013
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I was hoping I might be able to get some information from some of you who have done lined kydex or aluminum sheaths? I have a plan to make a knife with a kydex sheath (and maybe later with aluminum-Hartsfield style) and wanted some opinions. I’ve seen where some makers have lined a sheath with thin leather or in other cases with a synthetic material. I don’t want to lose the benefit of good, positive retention by putting something too thick inside, but also for some reason like the idea of a liner. Does the liner help with much specifically? Does it help keep the blade from scuffing? Which liner would you suggest and if it’s one of the synthetics, where do you source it? For the synthetics, how do you like to apply it?

Thanks in advance for any insights and help-I appreciate it.


Jeremy
 
Kydex can scratch a knife. However, if the sheath was formed with the proper clearances that should not be much of an issue. I do find though, that most of the scratching from Kydex sheaths happens on the guard from the retention fit. The lining wouldn't help much with retention because that is not where the retention happens. It happens where the kydex is molded over an edge or feature like a guard or heel of a blade etc. The lining might make the sheath a little quieter. I haven't lined any of my Kydex sheaths yet but if I did I would use the same liner as my leather sheaths. I use a pigskin lining leather which is very thin (.06mm) like the product in the link below. It's cheap and looks nice.

https://www.tandyleather.com/en/product/glazed-pig-lining
 
A proper kydex sheath will have the blade suspended by the handle/guard and the blade is hanging between both side of the kydex and the blade should not touch the kydex.

Scratches usually occur due to grit that made its way into the kydex sheath.

Hartsfield sheath was paper lined. Any and all liners can be contaminated with grit from use. I often make an aluminum sheath with no liners so it can actually be washed out with water.
 
I hate how kydex can scratch a blade, but I think I'm more worried about liners attracting moisture and staining/rusting the blade. Also, who knows what type of chemicals are used to tan, manufacture, or however else a liner material is created? I've read about it, but I personally haven't tried the liners... Oh, I also worry that the blade is going to cut up some of the liner over time, making it look bad and more likely to collect moisture, dirt, and other bad things. I've just resorted to telling customers that if they want Kydex that it can and will eventually scratch the blade once grit gets in. I tell them I took every measure to reduce the scratching effect, and to further maintain it to wash it out every other week or so if its being used often.
 
As pointed out (somehow) above, Kydex cannot scratch a blade by itself. It is just plastic, and it will never be hard enough. It is actually the grit that gets embebed in the kydex what scratches the blade.

Now the question is... will other linning material avoid getting grit embebed? I don't think any softer material offers a solution to that. Anything can actually trap grit, and humidity (if leather or fabric).

Mikel
 
AVigil said:
A proper kydex sheath will have the blade suspended by the handle/guard and the blade is hanging between both side of the kydex and the blade should not touch the kydex.

Scratches usually occur due to grit that made its way into the kydex sheath.

Hartsfield sheath was paper lined. Any and all liners can be contaminated with grit from use. I often make an aluminum sheath with no liners so it can actually be washed out with water.
Click to expand...


Very correct. Proper fit is retention at the guard, not contact with the blade. To prevent rattle, with kydex, a spot near the blade tip does need solid contact. No matter what sheath style or material, should we not expect show of wear from repeated removal and reinsertion? Any material can and will hold foreign material that can scratch or otherwise mar a blade finish, eventually.
 
Thanks for all the great responses. Maybe I’ll go ahead and do without the liner. I have a friend who has made a pretty cool kydex vacuum press and he’s done some holsters with it. I could definitely make some well form fitted sheaths with it... I have made one kydex sheath before but that was with the help of a master smith at a class I took and I definitely understand the retention takes place up at the guard area and not due to pressure on the blade. I’m not sure where the notion of a liner in there would equate to “better” in general came from. But I really appreciate the insights from you all.


Jeremy
 
Watch a few videos on how to make Kydex sheaths. A couple of layers of blue painters tape on the blade during the forming process should give you the proper tolerances in final construction.
 
Mikel_24 said:
As pointed out (somehow) above, Kydex cannot scratch a blade by itself. It is just plastic, and it will never be hard enough. It is actually the grit that gets embebed in the kydex what scratches the blade.



Mikel
Click to expand...
are you sure ? wikipedia quotes the hardness of kydex at 90 rockwell. i had read in the past kydex could scratch a blade because it was harder than the steel. https://en.wikipedia.org/wiki/Kydex
 
Found this.....

Different Rockwell hardness scales utilize different size steel balls and different loads. The three most common scales used for plastics are Rockwell E, Rockwell M, and Rockwell R; results reported from the Rockwell L scale are much rarer. Many other Rockwell hardness scales are used for metals, with Rockwell A, Rockwell B, and Rockwell C being the three most common. As seen in the charts below, the correlation between the Rockwell scales used for plastics is weak enough that attempts at conversion between the scales are discouraged.
 
Early on, i had issues with scratches from grit in kydex. I have eliminated this by the following:
1. two layers of painters tape on blade before forming.
2. I only rivet the bottom two rivets to hold the halves together for shaping. After all shaping is done, i can open the sheath and thoroughly clean it out. Only then I do I set the remaining eyelets.
3. a drain hole in the end of the sheath. This is for ongoing maintenance. The user can spray it out, or blow it out with compressed air and the water and dirt has a place to drain out.
 
Thanks, Kevin-that’s some good advice. I’m thinking I may just scrap the idea of a liner after all the info I’ve gotten in this thread.

Jeremy
 
Lots of good suggestions.

I hate making sheaths...F' making sheaths :)

So what I have done is a few things to lessen the frustrations
- Use enough Kydex , do not be stingy
- I use 2 layers of blue tape and one of Gorilla duct tape. This gives plenty of room for the blade with no scratching
- if making a 2 piece sheath, drill 2 holes, outside where the sheath will be, and rivet this before putting in oven. This will keep the kydex from moving in press.
- When pressing the sheath I like to leave it in the press until it is dead cold, this seems to give a crisper impression
- when you take the blade out the kydex will be held in postilion while you layout the holes and shape.
- Now here is one of the most important parts to keep the blade from being scratched in the sheath. INSERT THE BLADE WITH TAPE back into the kydex and then set all of your rivets. If you set the rivets without the knife the kydex will end up being tighter over the blade which increases the chance for scratches.
- Remove the tape and insert back to into the sheath and check fit. If it is a little loose, remove knife and apply, very gentle heat gun to throat and give a slight squeeze then hit with airgun to cool, test fit, rinse and repeat if needed.
- While fine tuning the fit with heat, take a wet cloth and wrap the sheath to protect it.

There is a lot more to making a good kydex sheath then people are aware of.
 
Adam- Thanks for the step by step, I’ll definitely be keeping those pointers in mind when I finally get to making one. I hadn’t thought of making sure the blade was in the sheath when setting the eyelets, but it makes sense. Thanks for sharing your hard earned expertise.


Jeremy
 
gudspelr said:
I hadn’t thought of making sure the blade was in the sheath when setting the eyelets
Click to expand...

Probably a bunch of people had a light bulb go off in their heads as well, why their kydex keeps scratching their sheaths :)
 
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