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Build Your Own Pocket Knife

Discussion in 'How I Made It: Tutorials' started by Mythtaken, Oct 7, 2010.

  1. Mythtaken

    Mythtaken Staff Member CKM Staff

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    It's been a while since I've posted. Between doing actual "pay the bills" work and fighting with a jammed mill, I haven't had much time to think about knife making. But work has settled down to it's usual crazy pace and I finally got the mill sorted (mostly) so it seems the ideal time to start a new build-along.:)

    This time, friends and neighbours, we're taking on a slippy. When it goes right, a slipjoint folder is great fun to make. Most of the time, however, it is a trial that will test your patience, willpower, and blood-pressure. Building a slippy can shake your confidence and expand your vocabulary. :censored:

    This project can be accomplished with simple tools. A hacksaw for cutting the metal, a set of files, lots of sand paper, and a drill press (even one of those cheap ones you put your portable drill into).

    For today, we'll simply start with a plan. I've chosen a very simple design that should be easy to copy and follow along with. Here it is:

    [​IMG]

    As you can see, there really isn't much to it: a blade, a backspring, and liners. But don't be fooled. These simple parts require the utmost precision. Be out by as little as .5mm and you'll be starting over. Plan to make several of both the blade and backspring.

    For those of you who would like to participate by actually building your own slipjoint, show us some pics. Start a new thread here and tell us about your progress. We can turn this into a true build-along. And for the rest of you just reading along, I need feedback on this thread. Am I covering the build well enough? Is there something more you need to make this useful? Let me know. This isn't much of a discussion thread if there's no discussion.
     
  2. Mythtaken

    Mythtaken Staff Member CKM Staff

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    Off to a slow start with this one. Life intervened once again, so I didn't get any time in the shop. However, I've made some initial decisions on material. I hope those of you playing along at home will share your material choices.

    [​IMG]

    As usual, I'll be sticking with O1 for the blade and back spring. With this one, I've decided to use 416 for the liners. Though I didn't include it in the photo, I'll also be using 416 pins. If you aren't comfortable with peining pins, go ahead and use screws for your project. You can also use a screw-type pivot pin to make things a little easier.

    In the design, you may have noticed the liner was marked for a bolster. For your own, you may choose to go with longer or shorter bolsters, doubles, or maybe none at all. I'm still undecided on scale material. I think I'll wait a bit and see what comes to mind as I progress.
     
  3. Mythtaken

    Mythtaken Staff Member CKM Staff

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    Yesterday, I finally got down to work. The first thing is to transfer the design to the metal pieces.

    When you're making a fixed blade knife, you can just shape the metal as you go, or roughly draw the design on the metal as a guide. For a folder, you need to be much more precise in transferring the design to the metal. Some people like to cut out the paper design pieces and glue them to the metal and some just trace around them with a scribe or marker.

    Once you've got the design marked on the metal, it's time to get out the files. You can use your belt grinder for the rough shaping, if you like, but you'll still need to do a lot of the work by hand. I prefer to just use the files. It saves belts and I enjoy the process.

    Don't try to shape the pieces right to the lines. You can take the extra off later but there's no way to add more. Especially make sure to leave the back spring a little longer than the design and make the notch (back square) in the blade tang shorter and shallower.

    Here are my pieces after initial shaping:

    [​IMG]

    In the next episode, we'll drill all the pieces and begin fitting them together.
     
  4. Mythtaken

    Mythtaken Staff Member CKM Staff

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    The saga continues. This time I drilled out the pieces and cleaned them up a bit.

    It's very important to drill your holes precisely and straight, or you'll end up with some more steel for your scrap bin. Clamp everything down tight, line up the bit carefully, and don't skimp on the cutting oil.

    I start with the back spring because the hole placement is more arbitrary. You need a hole at the end of the back spring and one along the spring itself, about 2/3 of the way from the front. That should hold it nice and tight while allowing enough movement in the front of the spring.

    Once that's drilled, use it as a drill guide for the first liner. You can either lay it on the liner and use something to mark through the holes into the liner or clamp it to the liner and drill through the holes. (Be careful not to enlarge the holes in the process.) Then use the first liner as a guide for the second.

    For the pivot hole, I go back to my design. I always mark the pivot centre in the design template. Lay it over one liner, mark and punch it, then drill it. Use that liner as the drill guide for the second (I put temporary pins through the other holes to make sure everything stays lined up.)
    Here's how it looks with the parts drilled and cleaned up a little more.

    [​IMG]

    I decided to go with integral bolsters, so once I'd drilled out the liners, I removed the metal from the middle leaving a bolster on either end.
     
  5. Mythtaken

    Mythtaken Staff Member CKM Staff

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    Now that the pieces are drilled out, I can get down to fitting them together. I pin everything to a block (only pinning the back of the spring for now) and see how the pieces line up.

    The first thing to deal with is the spring. I slowly file the end down until it's just long enough to hold the blade snuggly in the closed position, but not so it will bind. This takes patience. I have to pin it down, check the position, take it off, run a fine file over the end a few times, then repeat. A couple of strokes too much with the file and you get to make a new spring.

    Once I'm happy with the spring length, it's time to heat-treat it. I do that now because I can make the rest of the adjustments on the blade tang and I don't want to bend the spring during the process.

    Before heat treating, it's important to add some tension to it. I bend the spring down about a tiny bit (between .5 and 1mm). It ensures there will be some spring force between the spring and the blade tang. Then I heat-treat.

    I treat it like a blade, taking it up to critical and quenching, followed by one temper cycle. Then I clean it up and run a torch over the front part of it, until it turns a bright blue. You have to do this carefully, because it doesn't take long to change colour and if you over do it, you'll have to normalize it and start over.

    It should come out something like this:

    [​IMG]

    (Sorry for the blur. I was too close for the camera to focus because I wanted to capture the colour.)

    With the spring heat-treated, I can pin it tight on my test block and start to get the right fit between the spring and blade. After many tiny changes I finally got a fit I like.

    [​IMG]

    As it happens, the blade in this picture isn't the one I started with. I blame CBC. I was listening to the radio as I worked on getting the fit right and stopped paying careful attention. I took a little too much off. So I set that blade aside for another project and made a new one.
     
  6. Mythtaken

    Mythtaken Staff Member CKM Staff

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    I haven't had much time to work on things for a couple days but I did get a chance to think about it, which is generally bad.

    In this case I finally decided on the scales. I have a small chunk of cocobolo that is looking for a home, so I decided this is the place for it. However, I just didn't think my integral stainless bolsters would do it justice, so when I got a couple of hours to get back to the shop last night, I decided to make some new liners in brass.

    [​IMG]

    I just have to solder on some brass bolsters and sand them down to size. Then I'll be back to where I left off.

    I also found a bit of time to sand up the blade, do the heat-treat, and mark it.
     
  7. Mythtaken

    Mythtaken Staff Member CKM Staff

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    Time to wrap things up here.

    Once I'd sorted out the material finally, it all came together quickly. I soldered the bolsters on and filed them to shape, Added the cocobolo scales and sanded them down, and finally, put the whole thing together with brass pins.

    I don't have any pictures of the work -- it's all pretty basic stuff. Instead, here's a few of the finally finished project. Well, nearly finished, anyway. I ran out of 1500 grit sand paper, so I need to pick some to give it a last sanding, and it needs to be sharpened. If any of you were playing along, I'd love to see how yours turned out.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  8. BigUglyMan

    BigUglyMan Active Member

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    Great tutorial. Makes me want to get out the files and sandpaper and get to building.
     
  9. metal99

    metal99 Member

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    Awesome tutorial Myth, I am going to start on my first slip joint soon so I need all the info I can get :)
     
  10. Mythtaken

    Mythtaken Staff Member CKM Staff

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    Glad to hear it! I'd love to see some really nice folders here. Knowing your work, it ought to be a stunner.
     
  11. metal99

    metal99 Member

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    Thanks Myth, I will most likely do a WIP thread for it when I take the plunge. I'm going to make it out of O1 tool steel but I'm not sure how thick the blade should be. I was considering ordering some 1/16" O1. Is that to thin for a small slip joint with a 2" blade?
     
  12. Mythtaken

    Mythtaken Staff Member CKM Staff

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    I use 3/32, but If you're really going for thin and light, you could try 1/16. I don't think it will be very forgiving of mistakes though.
     
  13. metal99

    metal99 Member

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    3/32 it is :)
     
  14. metal99

    metal99 Member

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    Hey Myth, when you make your folders do you drill the holes under sized and then ream then to size?
     
  15. Mythtaken

    Mythtaken Staff Member CKM Staff

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    LOL! I would, if I'd ever got 'round to getting reamers (on the list...) So basically, I just drill to size. I haven't had any problems, except when using titanium for liners. Then I just drill the hole slightly larger to allow for the springiness of the Ti.
     
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  16. metal99

    metal99 Member

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    I think there's a little more room for error on pins with slip joints because you always have some spring tension. My old drill press isn't the most precise so I bet a reamer wouldn't bennifit me much lol.
     

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