Custom made kitchen knife
Before we start
The first thing to do is to design a knife. It is important to take into account two fundamental things - what the knife will serve and to whom it will serve. This essentially determines the final shape of the knife. In this case, it\'s a kitchen knife for my dad. He had several demands. In particular, it was a requirement for a thicker handle in the front (due to the specific holding of the knife when slicing). I adapted the rest of the handle to that. Furthermore, it was a straight blade and a slightly raised tip and finally a total knife size. The knife is designed for use in the kitchen, so I chose stainless steel, inlace, and stainless steel pins - everything is completely waterproof. And, of course, every kitchen knife should have hellish sharpness and, if possible, durability of the blade. The design site must not be forgotten because the knife is a work of art - so the choice of material for the handle is important. I chose the subtle "Blue Damascus" cool colors.
X50CrMoV15 stainless steel sheet 3x50x250 mm
Inlay block "Blue Damascus" 25x38x127 mm
5 mm stainless steel wire (for pins)
Five minute epoxy adhesive
Polishing pastes - polishing, polishing, high gloss
Tools used:
Angle grinder
Belt Sander (200 and 400)
Disc grinder
Polishing wheels
Clamps
Vice
80, 500 and 600 grit papers
Files (Round, Round, Flat)
Důlčík
Pedestal drill
Iron drill diameter 5 mm
Iron Saw (or Band Saw)
Hardening oil and hardening oil container (for hardening the blade)
Tempering "Oven"
Slider
Paper, pencil, ruler, scissors and non-stick adhesive such as classic Kores
Abrasive stones (different grain sizes - according to the required sharpness), steel
PRODUCTION PROCEDURE:
Knife Body:
1) At the beginning of each project, it is good, if not necessary, to design a knife and draw it on a 1: 1 scale paper. I recommend drawing the material dimensions on the paper first - a 50x250 mm rectangle. You draw a knife into it and you will be sure that the material is enough, or vice versa, that it will not lose too much waste.
2) Cut out the drawn knife and glue it to a steel sheet with some lighter paper adhesive - in our case X50CrMoV15 stainless steel
3) Draw a pencil or felt-tip pen on the parts of the sheet that overlap.
4) Cut the parts with an angle grinder to save as much later grinding as possible.
5) To prevent injury, clean the edges and burrs on the disc sander (in this case, except for the knife back - the template rests on it and chamfered and then the resulting shape is distorted).
6) Grind the basic shape of the knife on the belt sander, using a coarser grain (I use 200). I recommend that you place a wet rag on the floor - soaking the entire blade would get rid of the stuck contour of the knife. Without cooling, the paper template will burn again.
7) Use the nail file to sharpen the parts where you have not reached the grinder.
8) Measure and mark the bolt holes on the handle, mark with a punch and drill on the stand drill. In this case, there were two 5 mm holes. Clean up (I use a larger diameter drill to pull down any grots on both sides).
9) When the contour is finished, it is time to grind the blade to a hardening thickness of approx. 0.3 mm (belt sander).
10) Grind the blade surface on the belt sander to remove the sheet metal. Easily. Then repeat even with a finer grain (eg 400) to clean the entire blade surface. Do not forget the back and the whole contour of the knife - everything will be visible after sticking the handle. I do this step before hardening, because after that it is enough to just clean the blade.
11) The blade is ready for hardening. Check everything carefully and fine-tune. The manufacturer of the used steel recommends quenching at 980 ° C - 1050 ° C and into the oil. Then temper for 2 hours at 160 ° C. This should result in a hardness of 58 - 58.5 HRC, which is more than sufficient for a kitchen knife.
12) Tail and Loosen if you have how. If not, contact the specialized companies dealing with it. (More about hardening and tempering is at the end of the manual).
13) Grind the entire blade surface (belt sander, 400 grain size) and clean it from discoloration and dirt from hardening. IMPORTANT - keep in mind that the blade is already cloudy and you can soften the blade by overheating the blade and thereby substantially destroy the blade. Therefore, often chill in water. If your grinder allows it, reduce the speed and do not press on when grinding.
14) Blade polished (all places not covered by grip). If you have a grit size of 400 on the belt sander, start with 500 and then 600 sand paper. If you use machines, you will have considerably easier work, but do not underestimate this step. Use abrasive pads with a polishing pad and pastes for polishing, polishing and polishing. If necessary, finish with a "rag".
15) Now sharpen the blade on the belt sander, sufficient to sharpen the stone. I recommend using finer grain and taking time. Here, cooling in water is extremely important, for the reason described in point 13
16) Cover the blade with paper and tape it over, or make a temporary "case" of cardboard. Someone directly covers the blade with paper tape, but I do not do it after polishing. Leave the handle free and the part of the blade where the handle will reach.
Handle:
17) Using a ruler and a pencil, draw a center line on the material (in this case the "Blue Damascus" inlay block 25x38x127mm). The slider is suitable. Shrew can also be used.
18) Cut the block. The band saw is ideal because then you can attach the cut parts to the handle from any side without lengthy straightening on the grinder. When using a handheld saw, you attach the parts with the straight side of the outside of the block (or level on the belt sander).
19) If necessary, adjust the parts of the grip on the belt sander, which you no longer get after sticking on the handle. In this case it was the grip of the grip adjacent to the beginning of the blade.
20) Drill the handle parts with the handle one at a time: Fasten the handle part to the desired position on the clamp handle and drill. Make sure to keep the angle, it is important that you do not need to edit the holes later, gaps will arise, which can then be seen (see the resulting photo of the knives at the rear pivot). It is good to have a few millimeters on all sides, ie. overlap material - to work with the grinder.
21) Cut the two 5 mm long pins from a 5 mm stainless steel wire, depending on the width of the handle. The pins must protrude a bit on both sides. Make them longer if you aren\'t sure - cut off the protruding parts anyway.
22) Clean both ends of the pins on the disc sander so that they can be pushed in and "not stuck" easily. It would stay in bonding.
23) Now put everything together and check it. Fine-tune the details. Everything should sit beautifully.
24) It\'s time to stick. Carefully degrease the metal handle of the knife with technical gasoline. Coarse sanding paper (80) to roughen the sides of the grip that will fit on the handle and carefully remove the abraded dust (eg with a damp cloth and wipe dry). Then follow the type of epoxy that you have chosen to use. I recommend five minutes, you can easily do it with reserve and you will not have to wait until the next day to cure. Apply a layer of glue on the metal handle - just enough to prevent the glue from "slipping" when the handle is squeezed. Then complete the handle. Brush the pins a little before they plug them in. To do this, clamp the clamps to ensure even pressure across the entire surface. There is still time to wipe the glue that has spilled onto the blade by wiping it with a technical gasoline cloth - do so while it is still in a more or less liquid state.
25) After the adhesive has hardened, remove the clamps and cut off the protruding pins with an angle grinder to save grinding. This is advantageous because, when grinding off the belt sander, the pins are heated and could damage the inlays - no matter how small they are left.
26) Grind the profile of the handle on the belt sander. So far we do not care about the handle thickness. Simply twist until the metal part of the handle appears, defining the shape of the handle.
27) File the handle parts where you did not reach with the file using the file - just the profile again.
28) Now roughen the blade in the second axis, ie. adjust its thickness and shape the desired profile from above.
29) Cut off the edges (belt sander) and roughly shape the resulting handle shape.
30) Use the file and sanding papers to fine-tune the handle. Pay attention to all the edges and pads (I use a thin round file on them) and smooth out everything. Take the handle in your process to keep you comfortable. All you need to fit into your hand with a file and smooth with sandpaper. Inlace is greatly shaped, it\'s not hard work.
31) Handle the handle. First, smooth with fine-grained sandpaper (eg 500 and 600) and then polishing paste on the polishing disc. (I use a white, high gloss, white dry paste. If you can, you can use a green, rough polishing paste before.
32) Wrap the handle in a napkin and wrap it tightly with tape. The blade is sharpened on abrasive stones. Let\'s start with a coarser grain and then gradually get finer. Finally, pull the steel and possibly on the leather belt. I won\'t be more focused on sharpening - there are stacks of information and videos about it.
33) It is only necessary to wash the finished knife with lukewarm water (mainly the blade), wipe it with a paper napkin and try the sharpness on the “rubber” bun or overripe tomato.
Aleš Miláček
