Kydex tips for a newbie

C

cfelly

Joined
May 27, 2024
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6
I’m trying to make some sheaths for a larger project than a typical knife. First time ever working with the stuff. Need to mold approximately 10”x12”, using .08 - too big for a toaster oven so I’ve been trying to use a heat gun… thinking I might try our bbq next…. I’ve been banned from the oven, my husband says it smells too bad.. I didn’t smell anything…
I cannot seem to get tight lines, I tried to include pics to show what I mean but can’t seem to figure out how to load them. Any tips would be appreciated.
 
Load your pictures to a hosting site like imgur then use the little imbed link deal. You probably aren't getting your kydex up to the right temp and or not evenly. I usually use a heat gun but I rarely make very large items. 10×12 is big for a heat gun in my opinion, that's a lot of area to try to heat evenly. There is a pretty distinct smell to hot kydex but I don't really notice it anymore. A gas grill would probably work ok as long as you can keep it from getting too hot. I see people use a heat press for printing t-shirts pretty often these days, kinda expensive for something I do 3 times a year. Maybe snag a Panini press at a second hand store.
 
Tape your blades, cut oversize, don't overheat, press HARD,, wear gloves,.
For big pieces I have heard of people using big electric pans set very very low if you move it around a bit and use a heat gun for edges...maybe, but it will be fiddly to get it the press quick, before it cools.
 
thebrain said:
Load your pictures to a hosting site like imgur then use the little imbed link deal. You probably aren't getting your kydex up to the right temp and or not evenly. I usually use a heat gun but I rarely make very large items. 10×12 is big for a heat gun in my opinion, that's a lot of area to try to heat evenly. There is a pretty distinct smell to hot kydex but I don't really notice it anymore. A gas grill would probably work ok as long as you can keep it from getting too hot. I see people use a heat press for printing t-shirts pretty often these days, kinda expensive for something I do 3 times a year. Maybe snag a Panini press at a second hand store.
Click to expand...
Thanks! Here are the pics. It was hard to get everything evenly heated. I so have an electric griddle I could try. I included pics of the press I made, wondering if it’s not good enough. I use clamps around the perimeter, I probably could swipe my husband’s 40lb kettle bell to put on top too. I’m using a piece of cardboard as the mold, thinking it might be too soft, may need to switch to wood or something?
 
elasmonut said:
Tape your blades, cut oversize, don't overheat, press HARD,, wear gloves,.
For big pieces I have heard of people using big electric pans set very very low if you move it around a bit and use a heat gun for edges...maybe, but it will be fiddly to get it the press quick, before it cools.
Click to expand...
Thanks! I do have an electric griddle I could probably use. The heat gun took forever.
 
Griddle would probably work and maybe see about silicone grill mat to protect everything, they are heat resistant mats that you put between the heat and the item to prevent sticking. It definitely looks like you didn't get even heat and most likely enough heat. Also cardboard isn't very strong against compression forces so wood or some other material would probably work better, are you using multiple layers of cardboard? Wood glue between the layers would stiffen up the cardboard once dried. The griddle and heat gun for the cooler parts of the griddle wouldn't hurt, electric griddles often have cool spots because the heating elements don't cover the entire surface. My press is similar to yours and works ok, I think I need better foam, as I used kneeling pads like you did and I don't think I get enough definition sometimes. I believe the foam sold for kydex presses is a bit softer/more resilient and more heat resistant. Also I use just one clamp but it is a very strong clamp that gives tremendous pressure, I have even stood on my press to get better detail (I weight north of 300#). I can't tell what the shape you are going for on your item but making a wood model of your item would be easy if you used balsa or bass wood from the hobby store, both are very easy to cut and shape with hand tools, balso being the softer and easier of the two.
 
thebrain said:
Griddle would probably work and maybe see about silicone grill mat to protect everything, they are heat resistant mats that you put between the heat and the item to prevent sticking. It definitely looks like you didn't get even heat and most likely enough heat. Also cardboard isn't very strong against compression forces so wood or some other material would probably work better, are you using multiple layers of cardboard? Wood glue between the layers would stiffen up the cardboard once dried. The griddle and heat gun for the cooler parts of the griddle wouldn't hurt, electric griddles often have cool spots because the heating elements don't cover the entire surface. My press is similar to yours and works ok, I think I need better foam, as I used kneeling pads like you did and I don't think I get enough definition sometimes. I believe the foam sold for kydex presses is a bit softer/more resilient and more heat resistant. Also I use just one clamp but it is a very strong clamp that gives tremendous pressure, I have even stood on my press to get better detail (I weight north of 300#). I can't tell what the shape you are going for on your item but making a wood model of your item would be easy if you used balsa or bass wood from the hobby store, both are very easy to cut and shape with hand tools, balso being the softer and easier of the two.
Click to expand...
Just a single piece of cardboard covered in painters tape. I want it to be molded around something around 1/8”. I have some plywood I can shave down, might tape & try that. I have better clamps I could use & he has a bunch of kettle bells I could put on top if I can lift them...
Love the silicon mat idea. I use the griddle for pancakes so I doubt the taste of kydex would be good in that lol.
Thanks so much. I really appreciate it!
 
thebrain said:
Load your pictures to a hosting site like imgur then use the little imbed link deal. You probably aren't getting your kydex up to the right temp and or not evenly. I usually use a heat gun but I rarely make very large items. 10×12 is big for a heat gun in my opinion, that's a lot of area to try to heat evenly. There is a pretty distinct smell to hot kydex but I don't really notice it anymore. A gas grill would probably work ok as long as you can keep it from getting too hot. I see people use a heat press for printing t-shirts pretty often these days, kinda expensive for something I do 3 times a year. Maybe snag a Panini press at a second hand store.
Click to expand...
I feel like I saw somewhere that the arrows printed on the kydex sheet is the direction the shrinkage will occur when heated but now I can’t seem to find if that is correct or not. Do you know?
 
I haven't noticed any shrinking in my usage. I'm sure it happens in extreme cold, but during the molding process I haven't noticed any changes in size that can be easily noticed. I have never even seen kydex with printed arrows, but if they do print it likely it's because that is the strength axis. Like most sheet goods they are formed in in one direction and that long way is stronger.
 
thebrain said:
I haven't noticed any shrinking in my usage. I'm sure it happens in extreme cold, but during the molding process I haven't noticed any changes in size that can be easily noticed. I have never even seen kydex with printed arrows, but if they do print it likely it's because that is the strength axis. Like most sheet goods they are formed in in one direction and that long way is stronger.
Click to expand...
Good to know. Thank you!
 
You can buy a partial sheet of 1/8" masonite or "hard board" at Lowes or HD, usually an endcap in lumber with other plys like peg board or white board. Masonite makes a great 2 piece mold for kydex. Cut out shape with a fine jig saw blade, clean up the profile and then glue that piece down to another piece of masonite. Take the outside profile from the blank you just cut, clean it up and glue it down on another piece of masonite. Now you have a positive and negative mold. Heat kydex and press between the pieces. I've made sheath molds that way that press out a really clean and sharp kydex sheath that looks almost like a factory sheath.
 
The temp matters a lot. You’ll get a fee for when it’s ready (kinda leathery).

I used an old toaster oven and a laser thermometer.

Get the foam. Affix it to 3/4” ply to two pieces (that your project will go in between). Heat the foam up so it’s not as different in temp from kydex.

Place and squeeze it with those ratcheting clamps for wood.

Let it sit for a while.

Wear *clean* leather gloves, don’t squeeze it when it’s hot.

A cotton buffing wheel on a drill works to smooth the edges.

Use a caliper to mark the edges so you have enough space for your rivets.
 
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