Kydex
2/23/2019 version

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Kydex comes in different colors and thicknesses. I use Kydex-T in Cadet Blue, .093 thickness for most applications but I have used thinner pieces with success also.

The knife is a Fletcher Terry 05-111 Scoremate Plastic Cutter, available on Amazon for about $8.

I paid about $160 for the most recent 4' x 8' sheet that I ordered from Steve at Regal Plastics in Littleton, CO, 800-777-7342. That's about $5 per square foot. The price included shipping. I charged it on my VISA.

They cut the 4' x 8' sheet into four pieces of 2' x 4' and packed them in a flat wood-framed cardboard box. It took about two weeks for it to arrive at my door via UPS.

Subsequently, I started buying Kydex on eBay in 1' x 2' pieces. This size covers my needs now. I've found blue, black, white, and red in various thicknesses, but I usually order .093. I've also found Kydex on Amazon. Many sizes and thicknesses.

Here's some info about Kydex: http://www.kydex.com/ and https://en.wikipedia.org/wiki/Kydex

A pretty good net resource for Kydex is at: http://www.boedeker.com/kydex-grades.htm

IMPORTANT: I have switched to using a heat gun instead of an open flame for heating and bending Kydex. I should have done this years ago, but I erroneously tried using my wife's hair dryer, and it didn't work. One day, I borrowed a heat gun from a friend and that's all it took. I bought my own the next day and have been using it since. A recent Kydex question prompted me to make this change known.


Some tips on cutting and forming.

I mark the smooth side with a fine tip felt-tip pen. Sometimes I have to mark the rough side, but it doesn't mark as well. After working the piece, clean the marks off with a wet paper towel. Heating often erases the ink.

Allow for extra length at bends; 1/16 or so. Bends are never as sharp as you'd like. Perhaps a bending brake would help.

Plan for the rough side facing out and the smooth side in. Kydex doesn't scratch easily.

I cut with tin snips, and it's hard to get a straight line. I stumbled upon the Fletcher knife shown in the picture, and it works well. You must score the plastic, and then deepen the cut with repetitive strokes until the plastic is able to be bent and snapped. I also use a very sharp blade in my carpenter's cutting tool. Score several times on the smooth side, then bend on the scored line. Kydex will break along the score, if it's deep enough.

I file the cut edges to get the white surface color to turn blue and to true the edges. I use a 12" medium file and a fine file. File along the cut to true the edges and across the grain to really cut away material. If you lightly heat cut edges, they get a round, finished look.

I pop rivet Kydex, and it works great. Aluminum rivets are ok; use steel rivets for pieces that will get rough treatment. I usually use 1/8" rivets of whatever length is appropriate. Metal washers are helpful to keep the end from pulling out. Kydex is a little weak at holes; the plastic deforms a bit.

I used to use a propane torch to heat Kydex. I would use a low setting on the gas flow to keep the flame tip short and hold the Kydex about 1-2" from the flame tip, a bit closer to really heat it fast. You can see the Kydex surface change as the heat front passes across. You can also heat it over a gas flame from your kitchen stove.

I also use a disposable cigarette lighter to heat very small areas and to minimize heating adjacent areas. This won't work for bigger areas because the lighter gets too hot to hold.

For several years now, I've been using a heat gun I bought on Amazon. This is much better than using open flames as it helps keep the Kydex from discoloring as it is heated. Probably safer, too. Meh.

Heat Kydex until it gets flexible. Heat on both sides if possible. Try to heat along bend lines only to minimize distortion of adjacent areas. The longer you heat it, the more flexible it gets, right up until it scorches ;-)

You'll probably burn a few of the first pieces you heat, but you get the hang of it pretty quick. You have to get the plastic hot, through and through, and then it gets very flexible. I try to heat the bending seam part only. That way, the rest of the piece retains it's shape. But when you want maximum flexibility, heat a larger area.

Form or bend the piece then hold it in position for about 30 seconds while it sets up. Use a wet paper towel to speed setup for tricky situations. Hold under cold water to set quickly.

For really form-fitting pieces, I heat thoroughly then form around or against the part I'm matching. Use gloves to prevent burns. Kydex holds the heat pretty good once it's really heated, but it will cool enough to hold its shape in 30 seconds or so.

If you accidentally burn the surface, you can scrub some of the burn off.

Reheating a bend or a formed piece will cause the Kydex to straighten out almost flat again.

Best Kydex advice: practice with a small 3x3" piece to see how quick it turns flexible and you'll discover how long it takes before it burns.


One problem with using Kydex as a protective cover over an underlying piece of metal such as over a clutch cover on a CRF250X is that dirt can get behind the Kydex and then rub the metal cover below it. This may lead to so much cosmetic damage that the metal cover would be ruined.

Also, bolts that go through the Kydex get loose because the Kydex compresses as you tighten the bolt and the bolt never gets the right torque loading on the threads to make it stay put. Where possible, use nylock nuts for good retention.

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