Hi Instructables Community,
this time I would like to share my first complete knife building project with you. I know that some of my subscribers may ask "Hey whats with those knives you made in the past?". The answer to that is quite simple because this is the first time I went all the way including heat treatment, handle scales, polishing etc.
The reason for making this knife was that I wanted to make a special gift for my uncles birthday. He is a retired chef and since he already has a large collection of kitchen knives I wanted to make something that would stand out and can be used daily.
The entire knife was made from re-used/re-purposed materials but more on that in the following step.
Please let me know what you think of this project in the comments and don't forget to like & vote for me if you found this Instructable useful.
Step 1: Materials'n'Tools
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- Old saw blade preferably without carbide teeth - I did take some samples of this old saw blade previously to test whether the steel could be hardened with positive results.
- Some twine or leather sewing thread.
- Leather strip as a lanyard but you could also use paracord for this
A piece of hardwood (In my case I used a chunk of oak that was thrown away by the previous owner.
Pin material (I used 6mm steel rod which was offcut from previous projects)
- An angle grinder with cut-off disks, flap sanding disks & wire wheels
- Belt Grinder
- Bench Belt Sander - Both sanders/grinders can be substituted by file work and lots of hand sanding if you do not have those powertools
- Cordless Drill with HSS bits - For more precision a drill press would be preferable
- Deburring Tool
- Various clamps
- Sandpaper in the following grits (600, 1000, 1200, 1500, 2000) - Make sure the sandpaper can be used for wet sanding - I also recommend to use some windex for wetsanding
- Propane torch or other heat source that gets over 1200°C - I've used a large torch that would commonly be used as a weed killer. This puts out enough BTU to get my steel to hardening temperature. A small propane torch might not be sufficient for this job.
- Fire brick
- Japanese pull saw
- Scroll saw, band saw or table saw
- Linseed oil & wax
Step 2: The Choice of a Design
First of all you will have to come up with a design. Alternatively you could of course copy one that you like or use the template I have attached.
Since I want this to be a cutting tool that can be used on a daily basis not only for steak the design shouldn't be to heavy or bulky. So the lines were kept smooth and flowing which gives the knife a quite nice look.
Step 3: Prepping the Template
This step is pretty straight forward. Print the template and use a knife or scissors to cut it out. Don't cut directly to the outline and leave a few millimeters as a buffer standing.
Step 4: Before You Make the First Cut
To make the material easier to handle it is a good idea to use the template to determine how big the piece of steel is that you have to cut off from the rest of the saw blade.
For better contrast I used a white marker but you can use whatever color you have available.
The round/curved shape of the template allowed me to move very close to the periphery of the saw blade thus minimizing waste.
Step 5: The First Cut
This was a long straight cut and I do recommend to use a basic fence/guide to prevent the cut-off disk from wandering off its path. I used a 1mm thin cut-off wheel for my angle grinder for this cut and you can see in the second picture that it wandered off a few times. This can be quite annoying when this damages the surfaces in an area that you plan to use for the knife. So use a sacrificial fence.
Step 6: Gluing on the Template
Previously I would have removed any surface rust with the wire wheel of my angle grinder but since this part of the saw blade isn't that rusty I simply removed the surface rust with a paper towel.
A simple glue stick was all that was needed to glue the template to the steel surface. You could also use spray adhesive or any other fast setting glue. Make sure you cover the entire area of the template and take care to glue it down straight without wrinkles.
Step 7: Rough Shaping
The point from now on is to move closer and closer towards the outline of the template refining the shape in the process.
The first step in this process is to to remove the large chucks of excess material. Once again I used an angle grinder with a cut-off wheel for this step. Make sure you wear appropriate safety equipment and use relief cuts to avoid curved cuts that could shatter the wheel.
Step 8: Shaping
Once the biggest chunks were cut off I continued to refine the shape with a 60 grit flap sanding disk. This allowed me to remove cut marks from the previous step and move closer (approx. 1-2mm) towards the outline of the template.
Take your time with this step as you can easily remove too much material but at the same time you do want to try to remove as much as possible. Flap sanding disks are cheaper than belts for the belt grinder so try and find a balance for the use of the two.
Step 9: Refining the Shape
I continued the shaping on my belt grinder which gives me more control over the process. I started out with a 60 grit belt and moved to the template outline before finishing this step with a 120 grit belt.
Step 10: Center Punching
Before flattening the stock and during this process removing and destroying the template I used a center punch to mark the holes for the pins.
The center punch creates a small dimple into which the drill can bite. This helps preventing the drill from wandering off.
Not shown in the pics is that I enlarged and slightly deepened the marks. I did this because I was worried that the surface sanding in the next step could remove the dimples.
In hindsight I would directly drill the pin holes now instead of doing this later.
Step 11: Flattening the Stock
Since the saw blade had seen quite some use in its previous live I decided to flatten both sides to true up the stock. This process removes damages and tool marks from the surface and creates a uniform surface that is easier to finish.
For this process I used a belt sander and went through the grits until I had the result I was looking for.
You could use marking blue or a permanent marker. In this case I used an Edding 850 marker which as a very wide tip which makes it ideal to quickly mark large surfaces.
Step 12: Drilling the Pilot Holes
I would recommend to do this with a drill press and purchasing one is very high up on my shopping list.
For the time being however I have to use what I have. In this case a cordless drill will do just fine. With a little cutting oil the drill went through the material quite quickly. You will notice once you get close to the other side of the material he drill will have a harder time and might even start to bind. To avoid damage to your drill bits simply flip the knife over and you should be able to see a dimple like in the second picture. Take your drill and set it carefully against the dimple and start to slowly drill. You should be able to remove the remaining material quite easily leaving you with clean pin holes.
Step 13: Enlarging the Holes
The previous step was meant to make it easier on your drill bits. The pilot holes had a diameter of four millimeters but the pin material is 6mm so you will have to make those holes bigger.
Since the pilot holes have removed most of the material already you will have an easy time enlarging them with the 6mm drill bit. Once again used cutting oil and take your time.
Step 14: Deburring
The previous step created nice pin holes but if you look closer you will notice that there are also burrs left. Using a deburring tool or a larger sized drill bit will remove this burr. I would recommend to do this by hand as it will give you a better feel than using a power tool.
Step 15: Marking the Centerline
Using a permanent marker you color the edge in the entire area of what is going to be the cutting edge.
Use calipers to determine the thickness of the steel. Divide this measurement by two and adjust your calipers accordingly. Most calipers do have hardened tips and it is those tips that can be used to scribe the centerline.
Place your calipers on the edge with one tip riding on one side and the other scribing in the center of the edge. Repeat this process from the other side and you will end up with one line (or two depending on how accurate you worked) that runs along the center of the edge.
Alternatively you can do this with a drill bit that has the same diameter as the blade on top of a flat surface. Place the blade flat on the surface and run the drill along the edge. Repeat this from the other side of the blade and you usually end up with two lines that are close together which is fine too.
Step 16: Preparing for the Bevel Grind
Take a sacrificial piece of wood and square it up. Use a miter saw or table saw to give one side a miter that is equivalent to the angle you want your bevels to have.
Attach the blade to the wooden bevel guide with screws through the pin holes. I used some masking tape to reduce the amount of scratches to the blade.
In hindsight I would recommend to use metal screws with a flat underside and plastic washers to avoid damage to the knifes surface.
Step 17: Grinding the Bevels
This part is probably the work step that took me the longest. Not because it is complex but because I wanted to ensure that the bevels on both sides are symmetric/uniform.
Take your time and check the progress after every second or third pass along the belt. The closer you get to the centerline the more often you will have to check and cool the blade. Since there is less material now the blade will heat up faster and without cooling you might overheat the blade which can lead to undesired side effects & properties.
Step 18: Cleaning
In this step I simply removed any oil, color and other stains with some acetone and a lint free shop cloth.
This will help achieving cleaner results in the following heat treatment.
Step 19: Heat Treatment: Part 1 - Getting to Critical Temperature
The first step in the heat treatment process is to heat the steel up to its critical temperature. This temperature differs between the different types of steel and will have to know what kind of steel you are working with for optimal results. If you know what kind of steel you have you can simply look up its specifications for hardening, tempering & annealing.
If you however do not know what kind of steel you working with as is the case with this steel you will have to guesstimate. Some recommend it to a point where a magnet will no longer stick to it whilst others recommend a bright red which would indicate a temperature of around 810°C / 1490°F.
Heat the blade from the spine and let the heat travel to the thinner areas whilst trying to achieve an even distribution of heat along the area that is intended to be hardened.
There are plenty of ways to get to this temperature reaching from charcoal forges to gas forges.
I improvised a small gas forge with five fire bricks and a large propane weed burner that gets up to 1900°C hot.
Once my welding skills and equipment are up to par I will build a more permanent gas furnace/forge but for now this got me where I wanted.
Step 20: Heat Treatment: Part 2 - Quenching
Now that you have the steel at a high temperature you will have to quench it to harden it.
I used a vegetable oil for this but there are plenty of other oils that could be used.
Insert the glowing knife into the oil tip first. Do this quickly and submerge the blade as far as it is glowing. Once the blade is no longer glowing you can insert it all the way to cool down further.
Ensure you have enough oil and your quenching container is deep enough to allow a complete quench. Also please be careful as the quench oil might catch on fire - never us water to extinguish burning oil! Either use an appropriate fire extinguisher (Which you should have ready when playing with fire anyways) or another medium such as sand or a fire blanket to smother the flames.
Step 21: Heat Treatment: Part 3 - Testing
To test whether the hardening was successful run a file over your knife. The file should skip over the blade without biting into it while the sound should be at a relative high pitch. If this is the case the hardening was successful and your knife is now very hard but also very brittle. If you drop it to the floor it may shatter upon impact.
If the file bites into the blade the hardening was not successful in which case you will have to sand off any slag and try again.
Step 22: Heat Treatment: Part 4 - Removing the Slag
During the hardening parts of the blade start to oxidize which results in slag. There might also remnants of burned oil which could make uniform tempering in the next step difficult.
Get some 320 grit (Or similar) sandpaper and place it on a hard flat surface and begin to wet sand all surfaces of the knife until all the discolorations are gone.
Step 23: Heat Treatment: Part 5 - Tempering
Since the steel is extremely brittle we want to use a technique called tempering. During this process we will trade off some of the hardness against more flexibility. To do this all you need is a toaster oven or regular oven in which you can heat up your knife to 200°C (392°F) for one hour. After this let the blade slowly cool down in the air and repeat the process a second time.
You will notice that the steel has once again been discolored by the heat.
As with the hardening each steel has a different temperature and number of cycles so if you know what kind of steel you are working with you should look up those numbers as they will yield better results.
Step 24: Removing the Oxide Layer
In this step I removed the blue layer that was formed on the surfaces during the tempering process.
Although I could (and probably should) have done this with wet sanding I used my bench belt sander for quicker results.
Since the blade has been heat treated already you need to be extra careful not to overheat the blade which could ruin the temper.
Step 25: Preparing the Handle Material
This was done during the tempering cycles of the blade which gave me plenty of time.
It was also the time were I added a band saw to my shopping list because sawing out handle scale blanks by hand is no fun.
Lucky for me my Japanese pull saw made the process a little faster and yielded quite good results (considering that I'm not much of a woodworker).
I cut the scale blank a little over 1,2cm (1/2") thick which should give me plenty of excess material left for the flattening and other errors I might produce.
Step 26: Squaring the Handle Material (Sort Of)
Well I do not own a planer let alone a jointer so I had to square my handle material by other means.
I could have used my bench belt sander or a orbital palm sander for this but I decided to try out the disk sander on my belt grinder. This worked surprising well and was quick work too. I was able to remove the tool marks from the saw and square the piece up evenly.
Step 27: Refining the Edges and Bevels
The previous steps cleaned up most of the two large faces from oxide layers. I had to follow this up with cleaning up the edges and bevels too.
The belt grinder with 180 and 240 grit belts did a great job and got the bevels ready for polishing.
Step 28: Polishing the Bevels
I followed the previous step by using a 400 grit belt to polish the trow bevels. After this the cutting edge was already getting quite sharp although it still had some burrs left which would be removed later.
Step 29: Pre-polishing
Since I liked the finish the 400 grit created I decided to use that on the rest of the blade too.
This would be a problem but the small dimensions of the grinder would only allow me to polish the blade the way you see in the pics.
In the end I realized that I would have step up my game and build a full size 2"x72" belt grinder for better results.
Step 30: Tracing the Handles
I used the blade itself to trace its outline onto the handle material. Although I initially did this for both sides I later realized that I only need one side to start with.
Step 31: Cutting Out the Handle Scales
I used a small Dremel scroll saw although a bandsaw, regular scroll saw or coping saw could be used for this.
Simply try to get within 1-2mm of the traced outline but not directly onto it.
Step 32: Copy the Scale
With the first scale cut out simply use this to trace the second scale. When sawing the second you might saw on the line to safe of sanding/grinding time later.
Step 33: Drilling the Pinholes
If you do not have a drill press you can use this simple technique.
First test if your wood drill actually fits through the pinholes. Even if the HSS drill and wood drill have the same diameter you might find that the wood drill wont fit. Alternatively you can test the pin material as well. If the fit is not good you will have to enlarge the holes by running the HSS drill through the holes in the blade again. Do this a few times but do not use pressure as you will have to remove only minimal amounts of material.
Get a flat surface, preferably wood as it will be used as a backing board for drilling. You could also place the whole setup in a bench vise for this step.
Put your blade on top of one handle scale and clamp it down. (Tip: you can use some scraps from the handle material to place under the tip to keep the blade level).
Now drill through the blade and handle from the top.
Repeat this process on the other side for the other scale.
In the end mark the inside of the scales and the blade to avoid mixing up the scales.
Step 34: Connecting the Scales
You will want to ensure that both scales have the same shape so use some double sided tape and insert the pin materials to connect both handle scales.
Step 35: Shaping the Handle
Using a disk sander and belt grinder for this process worked out great. I was able to shape the two parts so they looked identical using the pencil trace on that was traced onto the top scale. If you do not have a belt grinder (You should get one) you could achieve this with a rasp, files and lots of sanding too.
Step 36: Fitting the Handle to the Blade
I sandwiched the blade between the two scales and connected it all with some double sided tape and the pins.
The objective here was to fit the handles to the outline of the blade. This was accomplished with a 120 and later 180 grit belt.
This is pretty straightforward but you need to take care to avoid removing material from the blade itself.
Step 37: Preparing the Handle Contours
For this step I started by dividing each handle scale into four equally thick layers. These lines would act as an orientation guide for a symmetric shape.
I then used a curved ruler to create a flowing profile that would complement the overall look of the knife.
Step 38: Shaping the Handle
With the guidelines drawn I was able to start shaping the handle with a coarse 80 grit belt for quick material removal.
I went up to 180 grit quickly since the 80 grit belt was too aggressive.
If you do not own a grinder you can achieve this with rasps and files.
Step 39: Refining the Handle Shape
To remove the rough marks and refine the shape I used a 240 grit belt and a lot of light passes with constant checking. At this stage all reference lines were gone so I had to do this by eyeballing it. You can also see in the pics that I mostly used the slack part of the belt to allow me shaping the curved areas.
Step 40: Preparing for Polishing
To prepare for the polishing I cut my wet sanding paper into 5cm (2") wide strips. The grits I used were: 600, 1000, 1200, 1500 and 2000.
I also made a small finishing jig which you can watch in the video below:
Step 41: Polishing the Blade
This is a long and tedious process but if you want a good finish on your blade there is simply no way around it.
Clamp your blade down and begin to wet sand starting with the coarsest grit. In my case this was a 600 grit strip, as a sanding block I used a strip of hardwood with a round profile on one side.
Although you could use water I prefer to use windex as it seems to yield better results.
During the sanding you want to make sure that you stay parallel to the blade and only sand on the push stroke.
Take your time and don't rush it since you will be able to see this later in the finish of the blade.
If you have buffing wheel you might want to use it as well once you progressed through all grits to give your blade a mirror finish.
Step 42: Shortening the Pins
You've seen the pin material in the previous steps where I used it to shape the handle and conform the blade with the handle section. To make things easier after the glue up I decided to trim the pins so they would only stick out a few millimeters on each side. This makes it a lot easier to grind down with the belt grinder.
Just place the pins inside the handle and mark where they should be cut. Make sure you know which pin is for which hole since in this case they have different lengths.
Step 43: The Glue Up
To be honest this is one of my least favorite parts when it comes to knife making. It is messy, it is stinks, you get glue all over the place and so on.
So before you start make sure you do a last dry fit of all parts and use some masking tape to cover all areas that will not be glued together. Get yourself a few pairs of disposal gloves and put them on over each other. I usually get three to four gloves on each hand. This reduces the amount of glue that is around the workplace and workpiece and makes the cleanup easier.
Use some masking tape to create a mixing surface for the glue (or use a cup, scrap piece of wood/plastic/cardboard etc.). I used a two part epoxy that requires equal amounts of resin and hardener to be mixed and squeezed two equal lengths of glue on the mixing surface. I mixed both components with a coffee stir stick until they were thoroughly mixed and then I mixed them some more.
Since this is a fast setting glue I had to work fast now. Spreading the glue on the handle surfaces and inside the pinholes was quickly done as was inserting the steel pins. I squeezed all parts together and removed as much of the excess glue as possible and used a number of spring clamps to hold the whole thing together.
No wait until the glue sets, to do so read the instructions for the glue and act accordingly.
Step 44: Fine Shaping of the Handle
Once the glue has dried it is time to go back to the grinder.
Carefully grind down the pins until they are flush with the rest of the handle.
I also used some shop surface cleaning wipes (not sure what type of liquid they use for them though) and removed any epoxy that was left on the outside. Since some of it had completely cured already I had switch between the grinder and the cleaning wipes constantly. If you have too much epoxy on the handle you will quickly clog up your belts.
I should note that I had to move the blade around in the last frame to get a focused shot of the finished knife. By accident I dropped it and it fell tip first to the shop floor. I almost had a heart attack but when I picked it up to assess the damage I found that the heat treatment must have been done very well. No scratch, no bending, nothing chipped for your entertainment I have attached a short video of the outtakes below.
Step 45: Sharpening
Although this is quite the lengthy process I do actually enjoy manual sharpening.
I recently purchased a whetstone with 3000/6000 grits for a very reasonable price and figured this would be the perfect occasion to break it in.
The first step is to soak the stone thoroughly. This is why I placed it in a water container a couple of hours in advance.
Starting with the 3000 grit I alternatively moved the bevels across the stone until the bevels had the same finish.
I moved on to the 6000 grit side and repeated the process until I was happy with the finish & sharpness.
I do finished the stone sharpening with a 10000 grit stone which was used to polish the bevels.
If you hold the blade in a way so light passes over it from the back you will be able to see a tiny remaining burr.
To remove this burr (or more accurately to bend it straight) I stropped the blade on a leather strop. I know that there are many that recommend using a stropping compound and I'm sure if you have some available you should use it.
Step 46: The Test
So was the whole time shaping and polishing and sharpening worth it?
Well I took a sheet of paper and ran the blade across one of the edges and the knife sliced through it smoothly and clean.
I don't know about you but this is one of the most satisfactory things for me. You start to think something up in your head go on to make it with your hands and then see it working and functioning as intended is just so great you really need to try for yourself!
Step 47: Finishing the Handle
I used boiled linseed oil and wiped it on with a rag. Once the oil had dried I followed with a linseed oil & beeswax mix to finish the handle.
Step 48: The Result
Of course had to test the knife on the intended subject before I could call it finished.
It cut through the steak like a hot knife through butter and although it is far from being perfect I'm very happy with the way it turned out.
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