Knife Making 101 (reductive Process)

7,562

114

9

About: General all around DIYer!!!

The reductive knife making process is the easiest and most accessible way of making your own knives in your garage or backyard. Basically, you will start with a piece of bar stock steel (or theoretically any hard material that you wish to make a knife from) and you will progressively REDUCE material until you have the desire form/shape. You are pretty much only limited by you imagination and how much you want to spend on equipment. The process that I will show you uses affordable materials and tools that you can get at most hardware stores or off of Amazon. After you have read through this write up, my goal is that you will be at a good starting point in designing and making your very own knife! SO...without further ado...lets get started!

Step 1: Materials and Equipment

MATERIALS:

1. Steel - The steel you use is 100% up to you! There are many characteristics to consider when choosing what type of steel i.e. edge retention, durability, ease of handling, rust resistance, etc. The steel that I typically use is 1095 high carbon steel. It is one of, if not the most, common blade steels for DIYers. It is relatively easy to work with, it's affordable, has good edge retention, and pretty resistant to rust if you take care of it. You can google different blade/tool steels to see if another type of steel suits you fancy, but I like tried and true.

2. Handle Material - Again, handle material is completely up to you! Some people use exotic woods, bone, antler, different plastics, etc. I choose to use micarta. Micarta is made by epoxying sheets of paper or fabric together similar to fiberglassing. The end product is basically a plastic handle. I like it because it's easy to work with, easy to clean and its very durable.

3. Epoxy - You will also need to use some sort of 2-part epoxy to aid in attaching the handle. I just use a cheap 2-part quick set epoxy I picked up at Harbor Freight and have never had an issue.

4. Pins/Rivets - These are also used to help attach the handle. Again, the specific material you use is up to you. I just use 3/16" galvanized rod I bought at Home Depot.

EQUIPMENT:

A lot of the tools that you may or may not need you may already have in your toolbox at home:

1. Rasps.

2. Clamps.

3. Pliers.

4. Misc. buckets, kitchen oven, saws, and other grinding/sanding tools are also helpful.

There are a couple of "specialty tools" that you may not have:

5. Tabletop sander and various belts of differing grits. I use a 1" x 30" belt sander I got from Harbor Freight.

6. Drill/drill press and various bits. A drill press is not a necessity by any means but it definitely increases the quality of the end product, in my opinion (another Harbor Freight purchase).

7. Angle grinder with grinding wheel and cut-off wheel. (more Harbor Freight)

That's about it! You can stay pretty affordable and basic or you can go all out and buy expensive really nice and fancy tools, it's all up to you and your wallet!

8. OH YEAH! Almost forgot! Some sort of eyes and ears protection!

Step 2: Design

This can be one of the most important steps in the process. If you get over ambitious with what you want and design something that is beyond your capabilities, or even worse, beyond the capabilities of your equipment, you may be disappointed and discouraged. I suggest starting basic and working up to more complex designs. None of the steps are particularly difficult but there is a short learning curve as to how each tool functions and feels, as well as, each tool's specific limitations. For example, the clunky nature of an angle grinder lends itself better to rough cutting and shaping rather than finer detail work or finishing. Also consider the grinding steep and deep angles can be difficult to do precisely with a belt sander and not clean enough with an angle grinder. Cases like that may require a spindle sander, again, fancier and more expensive tools. BUT with a steady hand and some patience you can make most anything work.

The first thing you'll want to do is to draw out your well thought out design ;) on the sheet of metal with Sharpie, the color is your choice but choose something that is easy to see :).

PRO TIP #1: I prefer to draw it out on manila paper with pencil first. It is a lot easier to transcribe what you see in your head into a visual form. It's much easier to erase and redo or redesign, as needed. After you've drawn it out to your satisfaction, cut it out and trace it onto the sheet of metal as before.

PRO TIP #2: Try to place you design somewhere on the metal as to minimize waste i.e. as close to an edge as possible.

Step 3: Rough Cutting

This step is exactly as it sounds, roughly cutting out the basic shape that you've drawn out on the sheet of metal. Clamp down the sheet of metal and use an angle grinder with the cut-off wheel attachment to slowly and carefully cut out the basic shape of your knife.

NOTE: The cut-off wheel is really only designed to cut straight lines so keep that in mind when choosing where you want to make your cuts.

Once you've cut our the basic shape, you clamp it down to your work bench and start cutting off any larger chunks of material that you don't need. After all the larger pieces have been removed, switch to the grinder attachment and slowly and carefully begin to remove more material, getting as close to your Sharpie line as you can.

A LITTLE PATIENCE GOES A LONG WAY!

Step 4: Fine Grinding/Shaping

Now you should have a chunk of metal shaped kind of like a knife :)

From here on out, we will mostly be using the belt sander for the rest of the shaping and finishing. In this step, we'll use mostly coarser grits such as 60 or 80 to "quickly" remove material to the final shape. Start by, slowly and carefully (noticing a trend yet?), grinding down all the edges just to the point where you can no long see the Sharpie marks. This will be the final "blank" shape. There should be a 90 degree edge all around the entire piece.

NOTE: If you want, you can go down to some finer grits to smooth out the edges but just be aware that the following steps may cause scuffs and scratches that you'll have to fine sand out again. IMO it best to just wait till the end :)

Step 5: Bevel Cutting/Grinding

Now the fun part! This is really where the knife starts to look like a real knife, IMO. There are two main techniques to make one of the two main bevel styles:

STYLES

Flat V Bevel - This is the most commonly used design, where you use the same angle on both sides of the blade, meeting in the center.

Chisel Bevel - This style is a little easier because you don't meet in the center. You select the desired angle and you keep removing material from one side until you reach the other.

IMPORTANT: When cutting the bevel, be sure to leave roughly a dimes thickness of material left. If you do not, you run the risk of the blade warping during the heat treating.

TECHNIQUES

Freehand - Exactly as it sounds, just hold the blade in your hand and doing your best to make even and consistent strokes across the belt sander. This technique taking a particular amount of practice but I have seen people who can freehand very smooth and even bevels! Better people than I!

Using a Jig - My preferred technique is to use a jig. The benefit of a jig is it is much easier to maintain the desired bevel angle leaving you to only have to focus on making smooth and even strokes through the belt sander. You can purchase adjustable jigs (fancier and more expensive) or you can build your own! Using a miter saw, you can cut blocks of wood to have the desired bevel angle and then gluing them together to roughly be equal to the length of the blade. For reference, the angle I prefer is a 5 degree jig angle on both sides creating a 10 degree bevel, but experiment with different angles and see what you like the best. To use the jig, you set the desired angle or choose the block jig of the desired angle, then clamp the knife to it.

NOTE: For cleaner more even bevels, make sure to perfectly (as close as possible) mirror how you mounted the blade when you switch to the other side.

Both techniques require you to take your time to make smooth and even strokes. The more attention you pay in this step, the better the final project will be! If you start to get tired or bored or disinterested, take a break, go get a snack, go do something else! Trust me, this step is best done with your complete attention!

Step 6: Drill Pin Holes (and Rough Cut Pins)

Drilling the holes for the pins can really be done at any step PRIOR to the heat treating. After the heat treating, the metal will be really hard and make it more difficult to drill through (but not impossible, so worry too much if you forget). Theoretically, there is no maximum number of pins, BUT I would recommend a MINIMUM of 2. This step is pretty self-explanatory but let me give you a couple tips/hints:

  1. Be sure to choose the drill bit that exactly matches the diameter of the pins you are using (I use 3/16'').
  2. If you have access to a drill press, it is definetely the better choice over using a hand drill to making perfect perpendicular holes.
  3. Try to choose a spot in the handle that is evenly space from the belly and the spine of the handle and evenly spaces, relative to each other. For an idea, look at your kitchen knives or and fixed blade knives you may have around the house.
  4. Clamp the blade to the work station! The blade may not be sharp but if the drill bit bites the metal, it can swing/kick at your fingers/hand with considerable force and it will not feel good...or so I'm told ;)

The pins can be made from any rod material. Just make sure to cut them a little longer than you need and grind off the burrs. Too long is better than too short (That's what she said?).

Step 7: Heat Treating (with a Hint of Tempering)

Heat treating can vary greatly, depending on your needs and the type of metal you are using. You can find a heating and tempering "recipe" for just about any metal online. Since I use 1095, that's the "recipe" I will explain :)

First, a bit of an explanation:

Why heat treat? The reason we want to heat treat is to bring the metal up to its maximum hardness. This is beneficial because it is the characteristic that allows the metal to hold a razor sharp edge, as well as keep that edge.

Why temper? Heat treating to maximum hardness comes with one really detrimental weakness, the blade is extremely brittle! For example, if you were to drop a recently hardened blade on concrete it would probably chip or break in half, kind of like glass! That's where tempering comes into play. Tempering removes a little bit of that extreme hardness which will help to increase the durability, BUT not too much. We need to find a happy medium...a good balance between hardness and durability. Enter, the recipe!

RECIPE

To heat treat, in general, we need to bring the metal up to its critical temperature then quickly cool it (but not too quickly that we run the risk of shattering). Critical temperature of 1095 is right around 1500 degrees (F), but that number is not super important, unless you have a kiln (fancy and expensive). For us, we will heat the steel in a makeshift forge using bricks, scrap lumber, and an air mattress electric pump used as a billow. The goal is to get the blade to that critical temperature which is characterized by glowing bright orange AND more importantly becoming non-magnetic. You want the blade to sit at that temperature for a couple of minutes to make sure it's heated through out (the tang/handle doesn't need to be hardened) then we will quench it in used motor oil. Some people say to warm the oil first by pre-dipping some heated scrap metal but I've never had an issue..but I live in AZ where the oil comes preheated ;)

NOTE: When you quench the blade, the oil will ignite so be careful not to burn yourself.

NOTE: You'll want to move the blade up and down and forwards and backward (similar to a slicing motion). Not side to side (similar to a paddling motion), this may warp the blade.

Once the oil no longer ignites, you can leave the blade in the oil to cool further. While you're waiting, begin preheating your oven to 400 degrees (F).

Step 8: Tempering

NOTE: When you preheat your oven to 400 degrees (F), that doesn't actually mean you oven is sittinf at 400 degrees. Different oven will vary. It is very helpful to have thermometer in the oven so you can see what the true temperature is inside your oven. I use 400 as the starting point.

For 1095, I prefer to tempering my knives right around 400-425, usually leaning closer to 425, depending on where I can get my oven sit more consistantly. Basically, all we are doing is bathing the blade at 425, or whatever for 2 hours, then letting it cool to room temperature, then repeating the process one more time. If possible, lay the blade on its spine so that it heats evenly, I don’t know if it’s super important but it’s what I’ve always been told and how I’ve always done it ;) That's it, EASY!

NOTE: Make sure to clean of the blade with some soap and water and a good scrub pad so you can see the color change of the metal once it is properly tempered. You want a burnt straw (brownish yellow) color as is pictured above.

Step 9: Heat Treat/Tempering Cleanup

From here, you will want use the belt sander to sand off all the black scale that developed during the heat treating process. Use you jig(s) to sand all the metal surfaces evenly and cleanly. This will also remove the yellowish coloring (that's OK!) but be very careful not to sand the metal too much between cold water quenchings. If you work a section too long and it becomes discolored (like that anodized purplish/blue color we've all seen), it means you have lost your heat treatment and that section of the blade has become compromised. I recommend only 3, maybe 4, strokes through the sander at a time, then quench in water, then repeat.

When you are done with this step, you will have a fully shaped and heat treated blade, minus the sharpened edge.

Step 10: Rough Shaping the Handle Scales

NOTE: During this next step, it is a good idea to put masking tape around the blade and any part of the knife you don't want to get scratched or get epoxy on.

I like to use the tang of the blade as a stencil to draw out on the sheets of Micarta. From there i will use various saws to rough cut the scales out and then use the belt sander to get the last bit. Like we did when shaping the knife blank, only sand down every until you can only see the Sharpie line, the rest will be removed after we epoxy the handle.

NOTE: DO NOT round off any of the edges at this point. We want to flat surfaces when we clean and true up the edges after we epoxy the handle. One exception, you may round the edge that faces the tip of the blade because after the epoxy sets, it will be very difficult to shape this edge without damage/scratching the blade.

Step 11: Epoxy the Handle Pieces

I recommend following the instruction on whatever epoxy you use. The cheap quick-set harbor freight epoxy I use requires you to mix equal parts from both tubes and you'll have a 5 minute working time before it sets up. It might be easier at first for you to do one side because 5 minutes really isn't all that long to work with but after you've done it a couple of times, you'll be fast enough to do both sides at once. First, you'll want to mix more than enough epoxy, too much is better than not enough. Then, smoothly cover the inside face of each scale (or one scale if you are doing one at a time) as well as the pins (if you're only doing one side, try to only cover the sections of the pins that will contact the scale and metal). Now, quickly but carefully assembly the handle (depending on the tolerances of your drill bit and/or pins, you may have to use a mallet to drive the pin through the holes). Once assembled, clamp it all together as pictured above and allow to set.

Step 12: Handle Cleanup

Depending on how much extra length you have on your pins, it might be best to use a cut off wheel to cut the majority of the extra off. Then use the belt sander to flush them up to the scales as well as sanding off the excess dried epoxy off the face, taking care not to remove too much material. You only want to remove the dried epoxy, not begin to shape the handle. Finally, using the belt sander to flush the edges with the tang (as pictured).

Step 13: Final Handle Shaping

Here is another fun step! :)

The sky is the limit! You get to decide how you want the handle to look and feel. You can just round the edges and call it good or you can round the edges, add divets, and polish it! How much work you want to put in this step is entirely up to you. I pictured a couple of different handles I've used in the past. You can use the belt sander, you can use a grinder, you can use any number of rasps, a Dremel tool, basically anything that removes material will work. You'll have to experiment with what tools you like the best to accomplish the designs you want. Take it slow and I'm sure you'll end up with something you're happy with!

Step 14: Edge Shaping (secondary Bevel)

NOTE: This step is not necessary if you are making a something like a kitchen knife, will explain more in a bit. If you are skipping this step, continue the primary bevel as before being very careful not to overheat the edge.

Now let's make this knife functional! The goal here is to make a slightly less acute bevel on just the edge. Remember that I use a 10 degree bevel. A 10 degree bevel or less is fine and dandy for a kitchen knife that won't see much abuse but for a survival/hunting/camping/EDC knife, you'll want something a bit more durable. Somewhere between 25 and 30 degrees is a good balance between durable and sharpness. I've never had much success using a jig for this step. I just use a really fine belt, around 400 grit, and make very careful light strokes at the approximate angle I want. It doesn't have to be perfect because the exact angle will be obtained during the actual sharpening step. Again, go very slowly and only do one or two strokes per side until the secondary bevels meet in the center.

Step 15: Sharpening

The final step! We're almost done! There are almost just as many ways to sharpen a knife as there are to make one. I prefer a kit that comes with a jig and various grit grinding stones, such as the Lansky kit I pictured. With this kit, it comes with a jig with multiple sharpening angles to choose from (remember we're using 25-30 degrees) with 5 stages of grinding stone starting with the very coarse to very fine. Whichever kit or tool you use, be sure to follow the direction and before no time, you'll have a razor sharp knife!

CONGRATULATIONS! You did it! You made a knife! that wasn't too bad, now was it? I hope you enjoyed my write up! If you have any questions, please feel free to ask!

Metalworking Contest

Runner Up in the
Metalworking Contest

Share

    Recommendations

    • First Time Author

      First Time Author
    • Toys Contest

      Toys Contest
    • Big and Small Contest

      Big and Small Contest

    9 Discussions

    0
    None
    robbied

    3 months ago on Step 15

    Please, use vegetable oil instead of motor oil, works exactly the same, but with less toxicity being emitted. Apart from that, a great instructable with good attention to detail.

    1 reply
    0
    None
    arkrayrobbied

    Reply 3 months ago

    Admittedly cost took precedence over what was most environmentally friendly. Using clean vegetable oil would probably create less scale build up and thus less clean up...something to experiment with in the future for sure! Thanks for the comment!

    1
    None
    taibhsegaeilge

    3 months ago on Step 7

    Hmmm, I have to mention one thing. The part you mention about pushing the hot blade backwards and forwards, and not side to side....not true, it has to do with the temperature of the quench and the correct quenching medium for the particular steel more than anything else. Shocking the steel in a cold quench is more likely to cause warping. Even if everything is done correctly it can still warp, so when quenched the blade needs to remain hot so as to allow correction of the warping.

    2 replies
    0
    None
    robbiedtaibhsegaeilge

    Reply 3 months ago

    This assumes that your quench medium is exactly the same temperature all the way through, if you swished to a 'cold spot' the blade is likely to warp.

    0
    None
    arkraytaibhsegaeilge

    Reply 3 months ago

    The quench medium and temperature always seemed like the actual important things to me! The "technique" of avoiding the side to side motion was just something I was told when I first started making knives and since at that step, you've already spent hours of your time grinding away, I always figured "better safe than sorry"...you know what I mean? All I know is I've never warped or cracked a blade yet :) but thanks for the input and confirming my initial thoughts!

    2
    None
    thomas7608

    3 months ago

    This is by far the best knife making article I have seen on the Instructable's WEB
    Site. Fantastic presentation! I sincerely hope you Win the Grand Prize, you
    deserve it.

    Thomas

    1 reply
    0
    None
    arkraythomas7608

    Reply 3 months ago

    I very much appreciate that! I tried to write a knife instructable that I would have wanted when I first started making knives!

    Thanks!

    Alex

    1
    None
    arkrayDIY Hacks and How Tos

    Reply 3 months ago

    It looks like there's a lot to it when you write it down, but in practice, it's not all that bad!