The Thermoform (Boltaron, Holstex, Kydex) Sheath Resource and Tutorial

[Invinoveritas1911]

******Under Construction. Please be patient as this will take some time to build this resource - I am working from phone and ipad.*******
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Good afternoon! My name is Jared, and I am the Owner and Bender of Paw Paw's Knife Shop. It has become apparent that we need a definitive thread for the Sheaths and Such Forum on thermoform sheath making. I will do my best to provide a collection of information resources, and a step by step tutorial here.


I invite all makers to please join in and add your thoughts, tips, and tricks!!!


I was not able to find a lot of information when I started, so I had to teach myself through trial and error, and lots of practice. I don't believe that there is only one way to make a sheath. So, keep that in mind - I am outlining the way that I do things. It doesn't make them wrong, right, etc - it's just the way I do it. I support innovation, so please ask questions or make suggestions, it will only make this a better resource. Don't be afraid to try new things and post the results, good or bad, we learn from both.


What equipment is needed?
Don't get me wrong, having the right equipment makes it a lot easier, but it is not necessary. You can make a very nice thermoform sheath with very limited tools.

Oven***warning***Do not substitute with a microwave or clothes dryer!!!
Press - this can be very primitive, I will elaborate later
Drill, drill press, drill bit in dremel, or a hole punch
Eyelet setter - in an arbor press, or the little thing you whack with a hammer and then cuss a lot.
Electricians Diagonal Cut....blah - dikes. You will be using these to cut out messed up eyelets. See above.
Dremel (roto tool) - I guess in a pinch you could just whittle it into shape, but I suggest at least picking up a cheapo.
Razor knife - I don't use one, but if you don't have a saw, this is the way to go. Just think Sheetrock.
Scissors - for trimming tape
Lots of pencils and more erasers
Ruler (flexible is good)
Scratch awl - sharp
Clamps


What equipment would be nice? (**Add model numbers, prices, pictures**)
You can find most of this equipment on a budget at Harbor Freight. I will be using them as they are just about in everybodies neighborhood, and online. Are they the best? Of course they aren't, but they will serve the purpose quite well. If you have a unlimited budget, by all means deck out your shop - just know it is not a necessity.


Knifekits.com has some equipment and all of the materials you will need. These people do good business, and are a pleasure to work with! The only reason I shop anywhere else is if Knifekits doesn't have it. I have never received an incorrect order - ever! Tip: order by 1p eastern and use their Fedex 2 day delivery option. If you are ever on the fence about ordering eyelets, Tek-Loks, or another piece of Black Kydex, etc just do it - you will always need them and it really sucks if you run out and have to wait.

Harborfreight.com
Knifekits.com
Usaknifemaker.com

Digital Convection Toaster Oven- It is one of the bigger investments, one of the biggest headaches to find, but worth it. Finding a huge toaster oven is like hunting for Bigfoot. This is what I found, it was a blem for like $100. I love the digital controls, it's big enough for sheaths up to a Scrap Yard 1311 and then some. In retrospect I would have paid $400 for this oven and still been happy with it.
Oster

Heat Gun - these are junk. The switch has broken on both of mine, so they are hard wired, you have to bang it for it to come on.......but hey it hasn't left me stranded yet. But, if I were you I would maybe get a step up. Not talking deWalt, just up.
Harbor Freight $15

Laser thermometer - you need this, it is a lie detector!
Harbor Freight $20 - $38

12 ton Shop Press - this is not exactly the "home" setup - but it's the way I do it and that's what I'm showing you. I will discuss other options later. There are tons of ways to squish the foam between two boards.......just let your imagination run wild.
Harbor Freight $129

12 ton Hydraulic / Pneumatic jack - this is if you are going to be doing LOTS of sheaths, have physical limitation, or are really lazy.
Harbor Freight $80???

1/3 hp Air compressor - this is used to power the air jack, but is also invaluable in blowing out your sheaths
Harbor Freight $55

Foam
Holstex Xtreme Form - just trust me spend the $, one of the single most effective improvements in definition
Knifekits $18 per square foot

Dremel
Harbor Freight is ok, but you might want to splurge on this
Bits
Stone drum
Stone drum
Felt

Drill Press
Harbor Freight $70

Kydex drill bits. Splurge on these
#6 & #8
Knifekits $9 each

Scroll Saw
Harbor Freight $70

1/2 ton Arbor Press - if the 1 ton has a bigger throat it is worth the extra $13($50)
Harbor Freight $37 or Knifekits $73 (pre drilled to accept the dies)
Eyelet Dies
Knifekits $35 per set. 1/4" first then 3/16" later if you need/want to

1x 30" Belt sander - you can add a bigger sander to the line up, but this is a detail shaping machine that can not be substituted with a bigger one.
Harbor Freight $40

Bench Grinder with buffing wheels. They have all different sizes, attachments, etc. I pretty much only use the buffer on the "mouth of the sheath.
Harbor Freight $30 - $50

2 1/2 gal Shop Vac
Harbor Freight $33

Scratch awl

Reamer

4" bar Clamps
Harbor Freight $2 each - get lots of them and put them within reach everywhere you are working.


What materials are needed?


Thermoform sheet (Boltaron, Holstex, Kydex - In order for my preference)
Knifekits

Blue painters tape
Try to find 2+" 3M or other Quality tape, most likely you will end up with 1.88"
About $8 per roll

Metal/aluminum duct tape
Lowe's or Home Depot guessing $12 for the wide stuff (FBM/NMFSH) and I think I got the bottom roll at WalMart for $8 to handle most everything else.


Eyelets
#8-9 eyelets - for your standard 2 layer sheath
#8-10 eyelets - for 3/4 layers....probably wait for a little while on that, but order the eyelets anyway they are good to have around for when Murphy visits.
Knifekits $10.19 - $12.77 per bag of 100




If none of this is making sense, no worries, we will be covering it all in great detail as I start the tutorial. The above part is going to be a reference you can look back on when we get to the part where you say "what the heck is a flugelbinder?" Or "where can I find a can of BS repellant?"

That's all for tonight, more tomorrow.....

 

[Invinoveritas1911]

Ok, Ladies and Gentlemen, on with the tutorial! Please, do keep in mind I am in the process of building this thread.

The first thing you want to do is protect your knife. This is probably a good time to talk about how you should do that, and go ahead and dispel some myths.

Does Kydex scratch my pretty satin finish???? The answer is no it does not!

One more time......NO, KYDEX DOES NOT SCRATCH YOUR SATIN FINISH!!!

The sheath is involved in the process, though. The thermoform plastic that we know as Kydex, Holstex, or Boltaron has surface hardness of about 90. This is impressive considering most of your knives are about 60. But, the thermoform is still plastic, and your knife is still metal, and in most normal circumstances plastic is not going to scratch metal. Think surface tension when you think of the hardness off Kydex. You can take a sandblaster with aluminum oxide and cut a car engine in half with it. The same sandblaster will have very little effect on Kydex, mostly just bouncing off.

So, WHERE DO THE SCRATCHES COME FROM????

The scratches come from Dust / Debris. There is a zillion different elements in dust in the air. All it takes is a little silica, or the like, to get caught in between the Kydex and your knife blade. The Kydex won't give, so if the debris is harder than your knife steel, the next time you draw your knife - boom you have a scratch! Rock and a hard place kind of thing.

CAN YOU STOP DUST/DEBRIS FROM GETTING INTO YOUR SHEATH???

Not within reason. So, that being the case you can do some things to help alleviate some of those scratches. The scratch only happens if the right elements get put together under pressure and motion. You can't stop the motion, but you can do something about the pressure. If you make the space between the blade and the Kydex a little bigger, you are relieving the pressure and minimizing the chances of friction/scratches.

Also, the less dust / debris the better. So, what attracts dust and debris like a magnet? OIL!!! So, when you think you are protecting your beautiful knife by putting oil on it, well you are protecting in one way but hurting it in another. See you put oil on the blade, now the blade attracts debris. You put the knife in the sheath, now you have debris and oil in the sheath. Do you see where I am going with this? The oil is protecting your knife from rust, etc but is heavily contributing to the degradation of your satin finish. Now I'm really gonna blow your melon........the same thing happens in leather sheaths, not as bad but it is there.

My recommendation is to use an alternative to oil like Tuf Cloth Marine or Frog Lube. These will protect your guns and knives, even in salt water, and go so far as to repel dust. I don't have any affiliation with any of these products, and I don't sell them, so there is no financial benefit for me to recommend them. I quit using oil two years ago and haven't looked back, I just wish somebody had told me years before.

Rant over. Decide for yourself, y'all are big boys and girls.

Now when we prepare a knife to go through the forming process you are going to be using tape, heat, pressure, confined spaces, etc. There is moisture in the adhesive, heat from the oven, and when you smash it all together in foam you can rust a blade in no time flat! So, there needs to be some sort of protectant used before you ever get started. Also, another monkey wrench in the works is that some of the adhesive from the tape will stick to the blade. There is not much worse than oil for grabbing dust, but adhesive takes its job very seriously. So, you can place a thin layer of oil on the blade before the tape, and then wash the oil off after. Or, you can use Tuf - Cloth before, and use mineral spirits to clean the blade after. Either way works, the point is to pay attention to what you are putting on your knife and in your sheath.

So, back to the sheathmaking process.

To protect the blade, during the forming process, and to form a sheath that will not harm the knife in the future, we are going to use a spacer on either side of the blade, in the choils, fullers, or any other odd shapes in the blade. The way that I do this is by using a combination of Blue 3M Painters Tape, and Aluminum Duct tape. You can play around with this to figure how many layers work for you. It is a balancing act - the more room, the safer the blade, but also the more it rattles(can equal scratches too). I use 2 layers of blue tape, and one layer of the aluminum tape, totaling 3 layers per side.

if you are going to mold anything into the shape of your sheath like a drain hole, choil spacer, etc it is best to put it together UNDER the tape. This holds everything together for your own sanity, but also makes everything "blend" together and makes a much more aesthetically pleasing impression.

Most knives have a choil of some sort, so get used to making these spacers. I use scrap pieces of Kydex. I use contact cement to glue enough layers together to match the blade thickness. I start by tracing directly from the knife, cut it out with the scroll saw, and then hand fit it with the dremel.

I think drain holes are a good idea, yes it will let moisture drain, but it will also let some of the horrible dust / debris we talked about earlier fall through. Is there a point to it if you are only going to scout carry, yes it makes cleaning the sheath MUCH easier. I put it on all of my sheaths. You can pick up 1/8" (for smaller knives ie RMD and smaller)and 3/16" (for larger knives R6 on up) dowels at your hardware store for pennies, and they work great for this addition. They should be cut into 3"ish pieces, and I hand drill out a hole in the end to accept the point of the blade.


***I will eventually replace the pictures with a current a-z set, however for now I will piece them together***

Place one piece of painters tape on the blade, making sure it is long enough to grab your drain hole spacer. Position your Kydex choil spacer and dowel on the tape.

There are quite a few knives that will require additional spacers like: HRLM, FBM, NMFSH, AA, TGLB, to name a few. Anytime you have a depression in the blade shape (choil, spine scallops, fullers, double edges, harpoon tips, recurves, upswept points) you have to think about its pathway as it is being removed from the sheath. The most common mistake I see is when people don't include a choil spacer, or a big enough choil spacer. This might aid in retention, yes, but the trade off is that choil depression in the sheath will drag the whole length of the blade while removing, and returning the knife. These odd spacers generally require some imagination to manufacture, and honestly one of the most time consuming parts of sheathmaking. Take your time. Invest your time! I know everybody wants to just get to the smash, but if you do not prepare your knife properly from the beginning, the sheath is going to suck - no matter how pretty it is. Most spacers I make from Kydex, some I have to use layers and layers of tape. Fullers for example, I find it faster to use strips of tape to fill the depression than grinding a Kydex insert. You might be the opposite, you might like to use something completely different. That's ok! Just remember that whatever you use has to be able to stand up to 300 degrees, and an lots of pressure.

After you have everything arranged on the first piece of tape, cover it with another piece. Take your time and make sure everything stays in place. Don't press the tape down firmly yet, just lightly put it in place. Put one more layer on each side, for a total of two per side, of the painters tape. Gentle.

The third layer I use is an aluminum duct tape. You can use a clear packing tape if you can't find the metal tape. You will get better results with the metal tape, so make the effort to find it. You will see both ways in the pictures below. The reason for this layer is to make a smoother impression in the thermoform. Think about a playground slide, smooth = a fun ride! Now think about a slide made out of tactical texture thermoform = OUCH!!! This is a ride your blade is going to be taking often. Be kind to your knife!

After the tape layers are all in place, I like to hit it with the heat gun for a second to soften the adhesive a little. Then I put it in the press just like I was making a sheath, and let it sit for a few minutes. This should give you a beautifully smooth surface to work from.

Not as necessary with the clear packing tape, as it's clear, but I wiggle the aluminum tape back and forth along the cutting edge so I get a very defined line. I mostly use scissors to cut the knife out, sometimes I have to use a razor knife. Cut as close to the line as you can. BE VERY CAREFUL NOT TO NICK THE EDGE!!! After you have it cutout, now is the time to use your fingers and rub it all down making sure everything is nice and smooth.

From what I read, heating the thermoform is a huge problem for most people. I don't know if the way I do it is the way your supposed to do it according to the manufacturers, and I know it's not the best for any single type, however I have come up with a process that works well with all three types. The first thing is you gotta be patient with it. Real patient! The longer you give it to warm up the better - if it hasn't been In the oven for 20 minutes, you are probably rushing it. What I will do is preheat my oven, and put the thermoform on top of the oven to preheat as well while I am doing the taping and prepping of the blade. I take the "preheated" thermoform from on top of the oven and put it inside at a temp of 200 for 10 minutes. When I do this, I put the knife on top of the oven to be preheating as well. Timer dings. Up the temperature to 225 degrees for 7 minutes. Timer dings. Up the temperature to 250 degrees, no timer. Put on your gloves, and using your heat gun(or hair dryer, etc) heat up the foam you will be pressing with, then warm up the knife too. Say that takes 1-2 minutes. You are now at a critical stage in the heating process, so no more timers, and don't trust your oven - it lies. Whip out your handy dandy laser gun and zap the Kydex. I generally find it to be around 265-290(your oven will likely vary). Crank it up to 275, checking the actual temperature every few seconds. When you reach 300 degrees it is time to rock and roll.

I think it is important to note that 300 degrees is too hot for most thermoforms, and you are on the threshold of scorching it. Most of the time it is warming up at much lower temperatures. I am only recommending that it peaks at 300 just as you are taking it out of the oven.

Thermoforms are very forgiving in that if you don't like your impression, you just pop it back in the oven and give it another go. However, if you scorch it - it's done! Don't use it or sell it, it's not safe!!! I will scorch a piece and get a pic of it. Until then, the scorched area will generally be a shiny spot. You will likely see some deformation in the shape by this point too.
***add picture of SCORCHED***


During this heating process, thermoforms act very suspiciously like BACON - it twists, shrinks, stretches, and does the hokey pokey. This is ok. At 300 degrees, after slowly coaxing it up to 300 degrees, it should be laying perfectly flat and super pliable. Sometimes, even after taking great care to heat it gently, it will curl up a little. It's not the end of the world, you are going to smash it flat anyway.

 

[J. Hansen]

This is great! Looking forward to more

 

[theHobbyist]

Only thing I'd like to add at this time, well not really add, but comment on, is your equipment list...

HOLY SOMKES THAT'S A TON OF STUFF!!!

For the beginners, you don't need all of that, like 1911 said if you have the right stuff it makes it easier.

I started with a hotplate, a non-contact thermometer, and a press I made for less than $10 and my sheaths came out nice.

The only things that I've really added was a heat gun and now I have a little toaster oven...

Also... Thank you 1911, it's been a while since someone put together a tutorial/WIP/How to/what ever the cool kids are calling it now-a-days.

 

[Invinoveritas1911]

Thanks Guys!

Hobbyist, yes - You are absolutely correct, and thank you for pointing that out!

Just so everybody is clear, the way that I make sheaths is what I would consider overkill, and over the top, and probably borderline eccentric sprinkled with OCD. However, that is just the way that I do things. I am going to deliver this info in full strength, if you will, it can be diluted to serve your application as you see fit. I would rather put up too much information, than not enough. I have seen a lot of "budget" tutorials, for lack of better words, and they are great for that purpose. Since those types of tutorials have been done, and done well - my intention with this thread is for it to be EXHAUSTIVE and DEFINITIVE. The encyclopedia rather than the cliff notes.

YOU DO NOT NEED ALL OF THE EQUIPMENT, OR INSTRUCTION, IN THIS THREAD TO MAKE A NICE, FUNCTIONAL, SHEATH.


****Please remember this thread is under construction, and will take some time for me to assemble the pictures, information, and add descriptions and commentary. Check back often as I will we elaborating, and refining.*******

 

[Invinoveritas1911]

Make sure you have a mental plan of how you are going to get the knife, hot Kydex, foam, and press all lined up before you take it out of the oven. Timing is very critical, you may even want to practice it a few times so you have a muscle memory for it.

I don't generally care for taco, or fold over, sheaths. They are not as strong as pancake, they are harder to mold, harder to work on, and have half the attachment points. The only reason I would ever opt for a taco sheath is if size was the absolute most important qualification for the application.

I have my press set up so that I have a REMOVABLE rigid plastic "top" and "bottom" that hold the foam pieces together. This is ideal because it gives you all the space you need to see and work.
(Picture)

Put your gloves on, don't be a tough guy with no fingerprints. I use the cheap HF gloves that have the yellow rubberized grip, and have had great success. It will be trial and error, some gloves will melt, others will leave prints on the Kydex.
(Add gloves picture)

Both methods start by placing the bottom plastic piece on the work surface. Place the first layer of pre warmed foam on top of the plastic with the "open cell" side up.
(Picture)
If you are making a taco sheath, you will need to pinch and hold it in place until you can get enough pressure from the press to take it over. This tends to be the only time my fingers get too hot.
(Picture)
If you are making a pancake sheath, you simply lay down your first piece of Kydex on the foam, place your pre warmed knife in the center, and then place the other piece on top matching the corners with the bottom piece. Once it is all lined up, you place the second piece of pre warmed foam on top with the "open cell" facing down. Then the plastic "top" goes on last. You can now just grab the whole assembly with your hands and put it in the press. Or, if you have small hands, you might rig up a couple straps you can cinch down to keep it all in place while putting it into the press. Think back to carrying your school books with your belt....

Once you have everything lined up in your press, apply pressure. You can do this with clamps, jacks, a vice, ratchet straps, you can sit/stand on it, whatever works for you. I use a shop press because I find it to be the easiest on me. I press until I have reduced the foams' thickness by about half. This is specific to the Holstex Foam I mentioned earlier. Yes, you can use all kinds of different foam. Results will vary, save yourself the aggravation and get the good stuff.

I generally set my timer for 10 minutes. Relieve the pressure. This is normally more than enough time for the thermoform to "set" but still exercise caution, as it might still be delicate. Take the knife/Kydex out gently and set aside to cool.

If you don't like your impression, just toss the thermoform back in the oven, go back and start from the heating directions from 225 degrees on, and try it again. It is important to note that you can not make a sheath "work" just by wanting it to. If it's not right, do it again. I know you really just want to get on with it, but all you will end up doing is wasting your time, and likely ruining the piece of Kydex.

Most of the time the two layers of thermoform are going to stick together like the were glued - this is ok. After they have cooled completely just "peel" them apart. If you are happy with the way the impression has turned out, TURN OFF YOUR OVEN BEFORE YOU DO ANYTHING ELSE!!!!!

Now you want to get out your ruler pencils, erasers, an eyelet, and the scratch awl - it's time to map it all out.

The way that I lay out my eyelets is to give the sheath a sleek, sexy look & to provide the most ideal mounting options. If you want to make boxy granny panty sheaths - more power to you - not my thing. I like for the sheath to play off the shape of the blade. This makes it more difficult to map out, but well worth it in the looks department.

The first thing you want to do is locate your starting point.

Drilling

Trace

Make your mark

Ream

Scroll cut out

Transfer shape

Inside view

Snips

Dremel Finger

Even up sides

Even wishbone top

Roughed in

Dremel smooth

Felt Smooth

Buff Smooth

Looking good

Eyelets

Arbor

Eyelets finished

Belt shaping

Raw edge

Sanded edge

Felt edge

Buffed edge

 

[Invinoveritas1911]

space

 

[dericdesmond]

Thank you Sir for taking the time to post such an informative thread :thumbup: I envy your set-up and attention to detail.
Love to read how others do what they do. Had I read it a cpl years ago it would of saved me a many headaches (& prlly once I move & upgrade the shop)

I too use scrap kydex for spacers but like you Im sure also have a crap load of the busse cardboard sleeves laying around. They are a little easier to cut with my minimal tools so Ive been using them as of late(along with masking tape). Last few sheaths Ive made I used some sort of clay that maker Kiah recommended in a thread a few months back. Few times I used it got get a little messy on the knife used to mold but overall I was very happy with sheath results.

The one thing I am pretty sure you did leave out though was the safety stuff. I often play it dumb and go without goggles (always seem to fog on me) but a breathing mask of some sort should always be used. I did not take it very seriously when I first started and have a feeling combined with other bad habbits will catch up with me eventually.
Also when handling the hot kydex I find the very thin cloth gloves with rubber hands I get at Lowes ROCK! (need to dbl check brand). Offer enuff protection when handling hot kydex for a few secs while also offering you the abilty to still manipulate the thin kydex.

Oh and a Alox awe, man I cant imagine how anyone servives without one of those Obviously people do :thumbup: Get er done bro and thx again.

eta-got a few cocktails in me so wanted to mention this before I forgot.
Buy Brown aka Dave Brown aka original open spine/kydex flame master told me last year at blade-If you ever scratch your sheath (within reason of course), take your heat gun to it a little, and bam, gone. One of the Best tips Ive got to date. Cheers
Eric

 

[El Bandit0]

Thanks for the great & instructive thread. Takes a lot of the mystery out of Kydex bending.

 

[grogimus]

Subscribed and thank you. I'm not sure if I missed it or if it's still forthcoming but I'm curious about your preferred attachment method.

 

[Invinoveritas1911]

All are welcome!

Eric, yes thank you for pointing out the safety issue. This is a very important subject, and will be covered when I get to it. Also, the tip David gave you is correct, Kydex does have the ability to "heal" itself. If the scratch is actually an impression, it will pop right out. If it is truly cut, it will minimize its appearance, but the cut will not heal.

Grogimus, this thread is far from finished. I just have very limited time, and am adding to it as I have the time. There will be a chunk more of it added tomorrow.

Stay tuned......

Have a great night!

 

[1776-SOLUTIONS]

Outstanding..............Thank you!

 

[Zaper]

Subscribed.

Very useful.

Can you elaborate about the diferent materials like kydex, boltaron and holstex? Which one is better for newbies? (I've read horror histories about boltaron curling, but never seen a picture, so I don't know for sure).

Thanks!

 

[SHOKR]

thanks a lot for this!!!
my sheath making skills definitely need improving and there are some really good tips here!!

 

[Mathias888]

wow, great tips here .. thanks for sharing!!!

 

[co556guy]

thanks a bunch!

 

[DAVE_M]

Solid tutorial! Although, that's a lot of equipment and it could be substituted for other equipment or different methods. I don't find the ream necessary, it's handy, but my small knife or 60 grit wrapped around my finger works well. The material burrs are very weak at the rim of the hole and pop off easily, in my experience. Everybody has their own opinion on tape, but it's necessary IMO. The thermometer is a pretty good idea!

 

[razorsdescent]

Thanks for this awesome tutorial, some of these concepts are most certainly going into my anticipated build.

 

[Fallbrook Forge]

This is amazing. Thank you.

Why do you prefer boltaron and holstex over kydex?

 

[Invinoveritas1911]

Greetings, and thanks for the comments everyone!

I'm still not done with this tutorial, but family health issues have kept me out of the shop for the last year. I am hoping to reopen the shop next month, and will be continuing the tutorial.

Have a great day! I'll be back soon.