Mini Molding Press for "Kydex" Plastic Sheets




Introduction: Mini Molding Press for "Kydex" Plastic Sheets

Hi, this is my first instructable,English is not my native language so I hope you'll understand what I'm trying to say,if anything is unclear please inform me to fix it or to explain it throughly.
Couple weeks back I was messing with making some small scale blade for my "better half"
birthday present,(what can I do, I'm cheap ba****d, no diamonds for my wife ;P) ,which turn rather good,well....for the first try.She wanted something like this Bear claw.I made it as a necklace pendant ,but after some thinking I realize that it's not very practical to have it on your neck ,unable to use the blade unless you unstrap the necklace and it wasn't so safe without guard.So we opted to make small sheath which could be placed on her key chain.So i looked for some Ideas on the web and find this "Atwood Knife and tool". Mr.Atwood using "Kydex" molded sheaths and have some great videos on how to make them.

For those who doesn't have a clue what Kydex is, here is some info about it. It's a thermoplastic sheet which means after you heat it , sheet became pliable so you can change it's shape ,after cooling down it's going to remain in new shape,it has very good reputation for rigidity,impact damage,chemical resistance and fire retardancy .After some searching I located local dealer here in Japan, price was right so i order some sheets(At this point I'm still waiting for the sheets) meanwhile I needed right tool to do the job properly,in other words cheap and effective.First i need some source of heat Some people say that heat gun is better option than oven,I personally don't have a clue because i haven't use one and i don't have money to buy heat gun which was pretty pricey around 70 bucks,beside i already had oven I usually use with my "super sculpey" clay figures.So much for the heat source.Next thing is Press,I saw some videos where old blanket or bath towel plus body weight were used,but i had enough tools, some parts and time to make proper one for about 10$.Here is the list of parts and tools I used to make this small press.
3pcs 10cm x 10cm x 5mm steel plate (I already had these , reason for small press $1.00 each)
2pcs 10cm x 10cm x 1 cm rubber foam sheet ( approx.$0.50 each)
1pc 5 cm steel door hinge ( $1.00,note, hinge was more square shaped one,see photos)
1pc M6 x 7cm U shape bolt and nuts ($1.00)
2pc M6 x 7
cm bolt and nut and nut grip ($1.50)
3 small steel plates for the locks ($2.00 for meter)

belt sander
home arc welder 110v very cheap and very good
dremel tool plus burrs
ruler and measure tape
stabillo pencil
polyester putty
Black spray paint
wire brush
vice grip

This instructable contains high temperature welding process as well as some other possibly risky actions and the Author is not professional in this field ,so before even begin with project I Assume you know what you're doing, so if anything goes wrong DON'T bother to hold me responsible.If you do it you do it on your own.thank you.

Step 1: Making Parts

Because the steel plate is so small I decide to go with adding parts such as locks and hinges to it, rather than drilling holes into plates and losing precious space.First step is to make stay for the front lock. I cut two 5 cm pieces of steel bar and drill the holes on both sides.Upper and Lower stay, both are similar in size only difference is that upper lock have U-shaped slot instead of hole,so it can easily be placed over lock pin(screw).Reason for holes on both sides of the bar is: one is used as a lock pin hole other one is used for welding, just to make joint stronger,please take a look at the photos it makes more sense.

Step 2: Welding the Hinge and Front Lock Stay

Step two is to weld back hinge on to lower steel plate.Man.... I do really suck at arc welding ,but bit of putty before surfacer and paint, will do the make-up job.But before make up be sure to knock the carbon residue from the weld with the hammer and small chisel and wire brush and expose the real weld ,if some spots look weak you can re-weld on top of it and make weld stronger , just clean it before you do it ... Otherwise you'll just keep welding on top of the residue and not get any real bond.My weld is ugly but I'm sure it wont fall apart. One thing to check is way the hinge is positioned.You want to have clean 90 degrees,in the other word you need hinge to be turned inside-out.Joint bulge should facing outward.Next thing is to weld front lock stay ,I'm not really "measure twice" guy so most of the positioning was just eye-balled before I clamp it and weld it together,only real measurement was the middle line on steel plate,It washed away after i quench the plates,if you need it more permanently you can use alcohol based marker instead of stabillo pencil.

Step 3: Modifing the Hinge and U-bolt

After your weld the hinge,it's time to modify the other side of it.We need to make two larger slots on both sides,if You have milling machine good for you, other wise drill the couple of holes,connect them with grinder and dress them with dremel tool.You should assemble the rubber foam and the plates so you can measure the length of the slots.make it relatively loose,we'll use the middle hole for locking the plate in place and add pressure to back of the plate. Reason behind the slot is following,with the slots you're not putting stress on the back of the press so the chances of material distortion is reduced to minimum,once the sheet is in place you add pressure on both sides and have it properly shaped. Now I need to add the U-bolt, this is the connection between upper and lower plate also act as a part of back lock.At this point i need to make another small steel plate which will fit the U-bolt, take look at the photo its self explainable.once you make it ,weld the U-Bolt to the upper plate as shown in the last picture.So here you go basically your press is done it only needs to be cleaned and make bit more prettier before the final assembly.

Step 4: Assembly

I still need to rust proof it and paint the whole press ,I applied Putty on large bumps and holes and sand it to even level ,although I could spend days on this step and make it really pretty ,I personally like the home made appearance so some marks and imperfections are left as they are ,You can also read it as : I'm too lazy for that sh**..he he he.I wont go into assembly procedure, picture tell a 1000 words,so take a close look.I put some pointers on the pictures notes.If you need any further info let me know .

Step 5: Performance

I just couldn't wait anymore , I find some plastic not "Kydex",but it became very pliable after heating it in oven, It didn't shrink up,so i gave it a try and make some molds and to tell you the truth I was very pleased with the press performance,crisp trace of the blade line even though the plastic was pretty thick about 5 millimeters.Here are some pictures of the first mold.I still have to work on it and i'll keep this instructable updated ,hope you like it and please any feed back is appreciated.

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    5 Discussions


    8 years ago on Introduction

    Real nice method i was using termoformig for the foam PVC but your method loog mutch easier especislly when we made just 1 or 2 pieces


    10 years ago on Step 5

    how do you actually mold it to take the shape of the knife? do you heat it up after sand witching the knife between the layer,s?


    Reply 10 years ago on Step 5

    Rubber foam pads inside the press will do the all the work once the press is closed, there is no need to reapply heat after process unless you need to loosen some parts for easier blade pull out,and in that case i recommend heat gun as source since it can be controlled better,hope this help


    11 years ago on Introduction

    Your English is very good. This looks interesting... Can you use it with Sintra?


    Reply 11 years ago on Introduction

    Thank you ,I assume if it's a thermal plastic you can use it with no problems,I'm no expert in this and I have never worked with Sintra,but from what i saw on their web site it seams to be very similar to Kydex,so i don't see reason for it not to work.Good luck... BTW i really need to update this since i made it, I've been using it for about 20 times now and i notice some thing that could be improved I'm pretty busy right now to edit this Instructable but if you have any question I'll gladly help you