Kydex Bending Troubles

Community General Discussions
1

Does anyone know any simple (i.e. no special tools required) methods for bending relatively sharp angles in kydex?

My brother’s a mechanic, and my father and I do all the carpentry around the house, so we’ve got a decent array of tools.
But, our cellar is no CNC shop.

This stuff is normally pretty floppy in smaller sizes, but it’s extremely so when heated.

I’m trying to bend multiple sharp angles in 1/8" static-proof kydex, but it just flops all over and won’t hold anything but a very round corner.

I’ve tried using a toaster (my professional strip-heater :stuck_out_tongue:).

I’ve also tried heating up a steel brick with a torch, so that I could bend it over the sharp corner, but the brick just absorbed all of the heat and dissipated it (I could touch it imediately after without any visible burns).

I’m going to go cut a form for it out of wood, now and try microwaving it draped over the form.

Hopefully, that’ll work, but I sort of doubt it.

I’m debating cuting the plate into seperate pieces and melt-fusing them back together at sharp angles with a soldering iron, but I want to leave that as a last option.

Most plastics that I’ve done that with become pretty brittle, which is not helpful in the corners of a backpack/chestpack.

I’m open to any ideas.
Thanks.

2

Hi Nick,
I’m a props guy from the theatre/movie world, and a teacher, so while I’m a noob robot-wise I know about this stuff…in a hack sorta way. So.

   Perhaps heating up a steel rod 3/8" dia or so and setting it between two sheets of 1/2" ply would work (like so,    =o= )

If your pieces are small an electric oven element (Ya I’m suggesting sticking your head in the oven, so make sure it’s electric ;-} ) or a charcoal lighter element could do the trick.

The two main things to concentrate on are;
-only put heat where you need it
-the plastic has to have time to heat all the way through (w/o burning)

Yet another approach would be to make, four 1/4" wooden heatshield plates, clamp those on with spaces at the bend area and try a heat gun, working both sides. Maybe a slotted pipe to let in your stock and concentrate the hot air?

…just brainstorming, hope it helps

-Werner

3

Hi nick,
I figured you would run into a little snag.
Kydex forms easily with heat, a little too easy when working with small pieces and multiple bends.

Always start with the “inside” bends first and work outward, plan on having more than enough material and trim off the excess.

dreadluthier’s advice is good, if you are trying to do something like vaccum form it… The trick is to heat only were you want it to bend.
The best way is to do this is with a heat gun, a good one. This will not work well if you cant heat it throughly and uniformally. What I do is clamp the piece to the work bench sandwiched between a piece of material (plywood or even that brick would work) then heat the kydex on both sides. As the material starts to droop fold it over with something flat and keep heating it!
This will give you a plyable material that will give you the sharp bend you are looking for.
One last thing, you may want to try thinner material, 1/8" is really thick. This stuff is very durable 1/8" is probably overkill and you would probably have better luck with the tight bend you desire using thinner kydex.
I would suggest 1/16", I usually use .063 or thinner for this sort of work.

Again this is good advice from dreadluthier, the key is to go slowly, if it goes south on you. Start with another piece and try it again. It may take a few tries if this is something you have not done before.

I have worked with plastics and composite fibers for the last 12 years. I started out as a composites fabricator in the plastics shop, so I have alot of “hands on” experience.
It helps if you have some tools to do this with properly, but what you have in your basement should work okay with some trial and error.

Hope this helps, there is really not much I can tell you other than some technical data, this is sorta like oil painting or playing the tuba, you learn it from doing.

Tinman :wink:

4

Oh yeah, one more thing.
This is important or you’ll really end up making a mess.

Let the kydex cool until it is comfortable to handle in between bends!

Let me know how it works out.
Tinman

5

Well, i’ve pretty much done exactly as you’ve said, except I’ve had to substitute other heating elements for a heating gun.

I got something that’s decent enough for the job by cutting out a mold to drape the kydex over out of wood.

Then, I took a soldering iron and melted the corners together, inside and outside (and burned them a bit, but that shouldn’t matter much).

Then I put a liberal amount of superglue on the inside, which should make up for the loss of strength in the melted corners.

When I get home today, I’ll get out my dremmel tool and sand and buff the corners until they look decent.
I’ll also have to cut off the excess that the bending yielded.

I’ll post a pic of the results.

The whole piece is slightly warped and mis-aligned, due to multiple bending trials, but it’s not really noticeable once I stick it on the bot, as the torque of bolting it down holds it into the proper shape.

It ain’t CNC, but it’ll do, I believe.

The biggest problem that I ran into was doing as you said and heating ONLY the exact line that I needed to bend on.

Toaster’s aren’t very precise.
:stuck_out_tongue:

Btw, you noted that I should let them cool until they’re warm enough to touch between bends.

I let them cool, of course, but I had been touching them with my hands the entire time, so I guess that’s not the best gauge.
Let them cool until they hold their own shape would be a better rule of thumb.

Owning to the peeling skin, and the fresh batch of scarring on my fingertips, though, I probably should have used gloves or something.

:laughing:

6

get 2 pieces of 90 deg aluminum angle and clamp the plastic sheet between the two angle pieces, heat, then let cool and serve.

7

Hi Nick,
Well by now you are probably aware that this is sort of an art form working with forming plastics. It takes most guys some time to get down the technique.

I would be suprised if this sticks for very long, most commercial super glue is not the adhesive of choice for Kydex. There is a two part epoxy specially made to bond this stuff together, I’m fairly sure they sell it at hardware stores. Besides if you did a good job melting the pieces together you probably won’t need it.

Very true statement, sorry if I wasn’t clear.

If this piece isn’t as nice as you would like it to be, I have some scraps If you want them and later you could try again, PM me if you’re interested and we’ll discuss details.
You and the other guys have been great in answering all my questions and helping me get started, so if there is some way I can contribute to helping do stuff like this I am more than happy to. :smiley:

Tinman

8

Well, I can’t say that I’m happy, but it’s definitely functional.

About the super-glue… BLASPHEMY!
Thou darest profane the holy super-glue?
Cower, peasant, under the sheer might of superior bonding power!

:laughing:

I’ve still got a bit of it left, so I shouldn’t need any extras.
Thanks for the offer, though.

:slight_smile:

BTW, microwaving a block of wood isn’t recommended.
The sap boils out of the wood and makes a big, extreemly hot mess.

I sort of found this out when I tried to heat up the kydex over the wooden form.
The wood absorbed all of the heat.
I suppose it’s because of all of the air pockets in the wood.