I've posted an instructable about making a fixed blade knife. It'll be useful to read that first, because in this instructable, I will not go over those steps again, but merely focus upon the nuances involved with creating a folding knife.  A link can be found here: https://www.instructables.com/id/Knife-Making/ 

This instructable is intended to be able to be read by those who are not familiar with knives, but I may use some unfamiliar terms by accident. If I do, please ask. 

Disclaimer: I'm not responsible for any injuries(likely) or deaths(unlikely) that may occur as a result of your attempt to follow this instructable, nor am I responsible for what you do with the information you have obtained from this instructable, nor what you do with the knife you have made. Follow your local laws at all times!

Unfortunately, I get caught up with the work sometimes, and forget to take pictures. Thus, I will be using several different models to demonstrate the steps. All the parts are the same, and the instructions to build them are the same, but just be prepared for a sudden change in the knives shown. 

This project is somewhat difficult, and requires familiarity with basic tools, as well as quite a bit of time. However, the price is decently cheap, and not counting the tools, only costs me around $25 per knife. 

I'm going to try to get this instructable out first, since I can't find another instructable of this type, and then fill in with extra pictures. Any questions are welcome!

Step 1: What Is a Liner Lock?

Feel free to skip this step if you know what a liner lock knife is. This step is just to familiarize those who do not know, and also give an overview of what we will be making. 

The liner lock was invented by Michael Walker, who altered the electrician's knife to create this folding knife, with a ball bearing as its detent. The lock, when made correctly, is very strong, and also allows for wear. 

The main parts of the lock are the stop pin, pivot, and the liner lock itself. When closed, a detent built into the lock holds the blade closed. A liner lock works because a spring in the side of the handle (usually titanium) is in the path of the blade and keeps the blade open until the spring is pushed over to the side. If one is right handed, when the knife is cutting edge up, the liner lock would be built into the left side, and will spring towards the right. Pictures will do the rest of this talking. 

Terms to know: 
Lock- what keeps the blade open (in this case, the titanium spring)
Stop Pin- What keeps the blade from traveling too far when opened and closed.
Pivot- What attaches the blade to the handle, and what allows the blade pivots on.
Backspacer- A chunk of material located near the end of the handle (opposite the blade). This is just a pillar of support the same   width as the blade and the washers. 

Scales- The handle materials. G10 is a really good material to start with- it's strong and easy to machine, although a mask must be worn to protect against the glass fiber it will release. Micarta is a less hazardous material. 
Pins- What holds the knife together. In the picture below, these are the two silver ones located near the blade, and the two brass ones towards the end. 
<p>This should clarify the old hardening process. If you have the time to watch it.</p><p>http://youtu.be/hw4Rl0uG7ok</p>
You should make a tut on how you use inkscape for knife designing. I cant figure it out for the life of me lol. And it would be so helpful to be able to check if the stop pin is going to work out well where its placed.
Haha, alright it's coming up!
im impressed i couldnt of made a liner lock with so few tools way to go!!!
You can work harden Titanium. However not so much with heat treating it. Some alloys can be hardened by heat but they eventually anneal after the treatment. I would stick to using you hammer to work hardening it.
Ah, thank you for clarifying. So is compacting the lock with a hammer the best way to work harden?
not really, as it would not be uniform. <br> <br>with work hardening alloys what is usually used is rolled stock that has already been rolled to the proper hardness, and you work it hardened. <br> <br>that being said antique bronze swords all have hammered edges to increase hardness. so it will definitely work, just not very uniform. <br> <br>most titanium alloys will work harden easily, so much that machining it is a pain because it will harden during the process.
If you want to harden the metal you need to cool it quickly after heating it. If you let it cool slowly the metal returns to it's original state. To harden it you want to heat the metal way up then quench it in oil. This process changes the structure of the metal. You do NOT want to use water though, this will make the metal brittle. Nice instrucable by the way. I'm no expert so for exact hardening processes I would do some research yourself.
If Wikipedia is to be believed, &quot;Water is one of the most efficient quenching media where maximum hardness is acquired,&quot; Apparently the Japanese tend to use water the most to quench Samurai swords too. They've been doing that for long enough that I think they may know what they're doing now. In order to make hardened steel less brittle you temper it.<br> <br> <a href="http://en.wikipedia.org/wiki/Tempering" rel="nofollow">http://en.wikipedia.org/wiki/Tempering</a><br> <br> But really it depends on the alloy what process is best to use.
water is considered a 'harsh' quenching media, that's why it's not recommended. if you quench in water microfractures in the steel can develop into big cracks. also you're more prone to warping and inducing stresses in the material. <br> <br>oil is a much 'smoother' quenching media, while still dropping the temperature of the material effectively to the required zone. <br> <br>in fact, where maximum hardness is required, such as gages and standards one would use oil followed by sub zero quenching, not water. <br> <br>water will work for most work though and i have been using it with success for quite some time. i've had bad warping and cracking from time to time though. and on precision parts i'd go oil with no question, ruining hours of work in seconds feels really bad. <br> <br>i said all this both from experience and literature, i'm fairly good at metallurgy , specially of ferrous alloys.
I was merely just adding my 2 cents. All of this most likely doesn't apply since the piece we are talking about is titanium and not steel. I'm sure hardening and tempering processes are much different. <br> <br>And no wikipedia is a good place to start research but never to end it. There is a lot of good information there but not necessarily written by experts.
Titanium is not usually used in the manufacture of knives so little data is available on the topic.<br> <br> <a href="http://www.ehow.com/about_4705418_titanium-knives.html" rel="nofollow">http://www.ehow.com/about_4705418_titanium-knives.html</a>
Yes, I did this for my other instructable, where I was using 1084 steel. However, this one's D2, and I just send it off to have the professionals heat treat it.
Not a bad little tutorial. <br> <br>You do a lot of hand work, so this may be right up your alley. <br> <br>Get some wet &amp; dry, 80 to 400 grit should do it for a nice satin finish. If you want shinier you have to go higher, I find 600 is usually enough for a hand finish, if you use precious metals then you have to go to 3000 for that mirror polish. <br> <br>Make sure you use oil for ferrous alloys. <br> <br>Trust me it will put your work into a higher class ;-)
After 600 grit I use a polishing wheel to get a mirror finish. I buy a lot of used pliers and do it to them.
You know pfred2, I used to thing that using a polishing mop (well a series of them) would give a mirror polish... first day doing a trade jewellery manufacture course taught me better ;-) <br> <br>One of the main problems with a mirror polish is taking photos :-)
You didn't have the right polishing compound?
Never heard of using oils, but I'll give it a try!
Oil and wet and dry, your hands do get dirty, but it's worth it ;-)
nice one!
Great 'ible!! I admire the dedication you gave to explaining each small step for newbies. On a project such as this, those little details can be critical. There was only one point that I think could have been clearer: the picture showing how the blade contacts the lock was too dark to see clearly. After reading this 'ible, you have me fired up to make one start to finish. I will look up your previous 'ible as soon as I finish this posting. <br>I have been putting handles on knives as a hobby for many years, and I too love the craft. In fact, I have the workngs of a knife scattered around my computer right now. I have never shaped but one blade, but I loved doing it, and will do more. For those not wanting to go through the trouble of making your own blades, I heartily recommend Premium Knife Supply, which sells high quality blades on ebay at reasonable prices. Their blades are 440C, are tempered to 57-58 rockwell, and are very sharp. I have bought over two dozen from them. They also have liner lock knives for you to put on your own handles. I usually make 300-500% profit on them, plus they make excellent gifts that are cherished.. <br>Again, thanks for the great 'ible!
Thanks for the comment! Hopefully the new diagram will help. Also, kit knives or blade blanks are a great way to start!
Thanks! The new diagram does an excellent job of explaining about the angle where the blade meets the lock.
I have always been interested in Knives and knife making but never tried to make one. I recently bought a locking folder with a lock \ unlock mechanism I have not seen before. I really like the style but it made in china (can't seem to find us made knives any more) and the first time I used the knife the tip bent out of shape so I have been thinking of making my own blades. this as well as other indestructible are inspiring me.
I have been thinking about making a knife. Your 'ible might be just what I needed to get me moving.<br><br>This is proof you don't have to have a huge shop full of equipment to make something cool.<br><br>Great job, and thanks for the kick in the pants to get me moving on my own knife.
Thanks. And when you do do it, please post pictures! And goodluck!
That knife looks like a R.J. Martin custom.
Had to check, but yeah, it does have his style. Although, sadly, not his finishing. He's a great maker.
wow. this is incredible...im not even ambitious enough to attempt this. i think ill stick to blacksmithing. When i have the bravery to try this i will be sure to check back here.
But blacksmithing requires many more materials and tools, not to mention effort. I'm a little confused by that.
i was talking mainly about the basics. if you do some youtube research it really just boils down to a hammer anvil tongs and fire. with that you can do alot.
Just blacksmithing huh? I'm pretty sure blacksmithing is a lot harder than knife making. Making a folding knife sounds hard, but it's just a lot of time and careful filing. Also, blacksmithing would probably tie in really well with making a fixed blade knife. Thanks for the comment!
Your welcome. and yes there are some more complicated aspects of blacksmithing as well. i think the reason im uneasy about a project like this is just because of the small intricate nature of it
Absolutely love this idea.
Do you mill your blade to final thickness or just file and sand? I came across anold Buck folder at a pawn shop with a broken blade. I forged a new blade out of 1094, left it a little thick and filed and sanded it down to to the right thickness. I recently came into possesion of an old horizontal mill. I think I will try try this project by forging milling and sanding. Good instuctible by the way.
Thanks. I buy my blade stock to be around the thickness I want it, usually 0.125&quot;. But I've never cared too much about thickness, so a little bit off doesn't really matter in the final product.

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Bio: Please visit my blog for more EDC and knife related things!
More by Batryn:How to Make a set of Lockpicks! How to load a strop (Knife Sharpening) How to make a liner lock folding knife 
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