By Matthew Parkinson
Download TutorialDealing with Medium and High carbon steels
When making a knife or any edged tool a high or medium carbon steel is needed. This kind of alloy is sometimes called “spring steel” or “tool steel”. When working with these steels the higher the carbon content and the higher the alloying content the more sensitive the steel will be to working in the correct temperature ranges. Some of these alloys can be red hard (a temperature range that the steel is hard to work) or red short (a temperature range that the steel is prone to cracking or crumbling) generally these problems are more common in high alloy steels, simple high carbon steels tend less to these problems but will develop large grain size if over heated or held at high temperature. Large grain size weakens the steel, is detrimental to the cutting ability of the finished knife or tool.
The best way to avoid damaging the steel you are working with is to know what alloy you are working with. Look that alloy up on line, or in one of the many reference books. Find out what that alloy is prone to, (if it is red short or red hard) what the hardening and temper ranges are. (you will need this info later) how ever with all of these alloys there are a few things that should be done. First Do not soak the steel in the forge, second do not heat the steel to a higher temperature than is necessary to work it, and third as you forge closer to finished shape work at progressively cooler temperature And finally normalize the steel before finishing the knife (filing grinding etc). To normalize heat the steel to critical temp, this temp can be found by using a magnet to find the curire point,(the point that heated steel turns nonmagnetic) critical temp is a few hundred deg. Higher than the curie point. Heat to critical and let cool in still air to about 400 deg F.(the temp that the steel regains magnetism is generally sufficient), do this three times ( or cycles) this will reduce the grain size break down any carbides that might have formed, and soften the steel making the grinding/filing easier.
In the USA Steel alloys are graded using two main systems, the first is a numeric based system (SAE, AISI) in this system there are 4 or 5 digits that determine the alloy, the first two determine the alloy content and the last two or three the carbon content, theses are called points, 100 points equals 1 percent by weight of carbon so 1050 steel would be a simple carbon steel (10=simple carbon steel) with .50% carbon content. The minimum carbon content to make a good knife is about 40 points (.40%) and the maximum is around 1%.
The second grading system is the letter number system of tool steels, theses are specialty alloys that were developed for a purpose so with in one set of steels (O series for example) there can be a total change of alloys with similar fished properties. Some of the more common steels in this system are O1,W1,W2 ,L6,S7 and D2. Many of these steels can make very good knives but some can also be very difficult to work.
Steps in forging a self handled or full tang blade
Steps in forging a blade to shape.
Step 1 forge the point
Step 2 forge the profile of the blade
Step 3 forge in distal taper (distal taper is taper in thickness from base of blade to point)
Step 4 forge in bevels
Step 5 set in the tang or grip area
Step 6 shape tang/grip area
Step 7 cut off knife from bar.
Step 8 refine the end of the grip/tang
Steps in forging a hidden or partal tang knife
Point Bar
Shape Point
Set in Tang
Cut off and forge Tang to shape
Bevel cutting edge
Grinding Steps
Shape profile
Grind Bevels/Ricasso (Blade is ready for heat treating)
Fittings
Fit and shape guard
Drill antler/Polish and glue to complete knife
Forging the shape
Begin by deburring the end of the bar, easing the edges is sufficient. Now take a forging heat on the point of the bar,( a forging heat is a bright orange heat) set the end of the bar on the far edge of the anvil and hammer the top corner back into the bar. Every other heat forge the thickness back in line with the parent bar. By rotating 90DEG and hammering the flats (work both sides of the flats)
Forging in the point in this way avoids fish mouth. ( the end of the bar folding over it’s self, forming a crack) when working with off size stock forging a point as you would in square stock will lead to fish mouth. As the center of the bar will not move as fast as the out side. Once the bar has been taken to a point begin refining the shape of the profile into the perform of the blade shape. Take care as you forge in the shape that the flats do not get wider than the parent bar and that the bar stays flat.
Once the shape is forged in taper the thickness (distal taper) the point of the blade should be about 1/8”or a little under, and taper to the parent bar thickness at the hilt side of the blade. To taper the blade take a forging heat, and forge the point down to about 1/8” then work back toward the hilt tapering the flats, re forge the profile as needed.
Forging in the tang
Once profile is forged to shape, set in the tang using a spring fuller or the corner of the anvil. Be sure to account for the amount of growth in length due to beveling, if a certain length is desired bevel the blade first then sent in the tang once the blade is to length. The tang should remain ½ to 2/3 the width of the blade at this point, cut off leaving 1-2 inches of stock after the step forged in from the spring fuller for a partial tang. Then, forge out the tang to a taper 1/3 to ½ the length of the handle, for a stub style tang. If making a through tang or full tang knife. Be sure to leave more material on the knife when cutting off and forge the tang out to 1-2” longer than the finished knife handle. The extra length can always be easily trimmed off but adding length is much more difficult.
Tips
- Use the end of each heat to flatten the blade before re-heating.
- Only work the steel down to a bright red heat. DO NOT soak the steel at a high temperature in the forge.
Forging in bevels
Begin forging in the bevels at point of tang, to do this angle the cutting edge side of the blade on the anvil and strike at this same angle, strike as near to the edge as possible and once a bevel is established shallow out the angles and begin working higher up on the blade to shift the bevel up the side of the blade until it reaches the spine. If leaving a ricasso pinch out the beginning of the bevel by hammering inline with the edge of the anvil and drawing out the edge. Once pinched in the ricasso should NEVER be on the anvil when forging the bevels in.
Because the edge is expanding as it is forged thinner, the blade will curve away from the edge. Correct this at the end of each heat, when the blade is still in the reds by setting the spine of the knife on the anvil and firmly hammering the edge back to straight .As the bevels are forged in be sure to work both sides evenly. Flip the blade over and work the other side keeping the same angle used on the first. It is best to work both sides in the same heat, but if this proves difficult a workable option is to alternate side to side from one heat to the next. As the bevels are forged in concentrate on keeping the edge centered the bevels even and of an even thickness , forge the bevels to a thickness about that of a dime at the edge.
Refining and Straightening
Working cooler (dull orange-dull red heats) refine the shape in bevels using a lighter hammer with little crown. Use light blows with hammer to even out the edge. Work both edges down to even thickness, then refine the bevels and flatten the blade by sighting for thick spots or bends. work only on the facets or the bevels never on the spine. Soap stone or chalk can be used on the edge to help sight the blade for flat/straight. Work cooler as final shape is reached, The last 2-3 heats of each section of the blade should be in the reds. This will help reduce grain size and leave the steel in it’s softest state for grinding. Once the blade is as straight and flat as possible, take a normalizing heat. To normalize, heat the whole blade to non-magnetic and cool in still air.
Tips
- After normalizing, clamp blade point side down in vice to cool.
- Sighting the blade against a light colored wall can help to see inconsistencies in edge and bends in the blade.
Steps to Forging a Self Handled Dagger
1) draw a taper
2) profile blade
3) forge in bevels
4) cut off
5) shape grip
6) grind, polish and heat treat.
Steps to Forging a Hilted Dagger
1) draw a point on bar
2) profile blade shape
3) bevel edges
4) set in tang
5) forge out tang
6) grind/polish and heat treat.
7) make and assemble handle
(steps three and four may be reversed.)
Dagger Handle Construction Methods
Full Tang
This style of knife has a tang that is the full width and length of the grip. Bolsters are common, but guards and pommels are not. The grip is made up of two slabs pinned and glued to the tang. Self handled knives also fall into this category. This is a strong handle design, but is prone to moisture damage.
Partial Tang
This style of knife has a tang that passes partway through the grip and is pinned or glued in place. Guards and bolsters are common but pommels are not. This style is almost always used with antler crown grips. This is a sturdy and stable method, but in some designs can lead to a poorly balanced knife.
Through Tang
This style uses a tang that passes through the length of the grip. Guard bolsters and pommels are common. The end of the tang is secured on this style by peening, threading into the pommel, with the use of a decorative nut or in some cases by pinning. This is a very strong construction method when designed properly. Even most Western swords use this style of construction.
Beveling Double Edged Blades
Forging the bevels on a double edged blade is much the same as on a single edged blade just done on both sides. The tick is to forge all four facets at the same angle and all four facets of the diamond must be worked evenly. You can work from the tang to the point or from the point to the tang. Again use the same angle in all 4 facets. The blade will not curve if the bevels are forged in evenly each heat. This is a good indicator that you are forging evenly. Be sure to match hammer angle to angle the bar is held to anvil on ALL FOUR facets. Carefully forge the bevels up to the ricasso (if present) or into the tang if no ricasso is present. Work the edge down to 1/16” or so and forge the bevels until the spine to the edge is one plane of a flattened diamond.
Tips for beveling
Flatten and straighten at the end of each heat. Work only the flats of the bevels to straighten.
Cork screw is caused by changing angles from facet to facet. To correct set the height of the twist down and forge high up on the bevel increasing angles. Work both opposing facets.
Grinding
Using a worn coarse grit belt, grind the edge on the flat platen or contact wheel of the grinder. Clean up the profile of the blade, re-shaping the tip as necessary, until the blade is even and centered. Next, run the blade edge vertically on the grinder so all grind marks run vertically on the edge. Next, use a small wheel attachment on the grinder to even out tang junction or grip area of knife. If a small wheel attachment is unavailable, use files to refine shape of the tang or grip. The joint area between the tang and blade should be at least a 1/8 radius (1/4 inch circle), ideally with no tool marks crossing the edge. This will prevent stress risers from forming and make for a stronger blade.
Once profiling is complete, begin grinding the bevels using a worn coarse grit belt on the flat platen. After the scale is stripped off use a fresh grit belt to grind the bevels flat with the edge up. When grinding everyone has a weak side and a strong side. Begin grinding with your weak side and match your stronger side to it, as this provides more control. Grind the bevels down until the spine is centered and even, the edge is of even thickness and about the thickness to of a dime. If the design has no hard plunge cuts, move to an 8- inch contact wheel with a 120 grit belt and grind the bevels vertically, until all coarse grit marks are removed. If the design calls for a hard plunge, re-grind on the flat platen. First grind using 120 grit, then grind with 220 grit. At this point the blade is ready for heat treating.
Tips
- If tang is not square to center line of blade, file or grind until even or square.
- If blade edge is of uneven thickness side to side or along one edge this can cause warping during hardening and will making sharpening difficult. Regrind thicker sections to match, adjusting the angle of bevel to keep spine centered.
Basic Heat treating
Basic heat treating for knife making is a three step process, it is the heat treating that is the most important part of making a knife. It is heat treating that turns a Knife shaped object into a knife. Step one normalizing, step two hardening, step three tempering.
Step one
normalizing, heat the blade to a orange heat and let cool to still air down to a black heat, do this three times . this will remove any stresses built up by grinding, reduce the grain size, and leave the steel in the best condition to be hardened.
Step two
Hardening is heating the blade to critical temp.(the temp. at with all carbon is in solution with the iron) and quenching it (in most cases in oil.) this will force the steel into it’s hardest state. Critical temp varies from alloy to alloy (usually between 1450-1550 DEG F) to find critical, heat the steel and check it with a magnet, the temp at which it looses magnetism is called the curie point, about 100deg above this point is critical. In practice quenching from the point that the steel looses magnetism is close enough. judging the temp by color is affected by ambient light so even if when using a steel you are familiar with it is a good Idea to check the temp using a magnet. Heat the blade to this point and quench the blade in oil, quench the blade, edge down or tip first in oil, do not angle the blade when entering the quench or the blade will warp. For most steels vegetable or peanut oil works fine and is non toxic, motor oil can also be used,(fresh not used). For a more consistent quench and when working with faster hardening steels a commercial quenchant like Parks-50 should be used. Quench the blade until all color is gone from the blade then let cool to room temperature. Check the edge using a file to be sure the blade hardened, if the file “skates “ then proceed to tempering. If the file “bites” the blade didn’t harden, reheat to a slightly higher temp and requench then check again. If the blade still isn’t hardening the edge may have decarburized, lightly grind the blade and check again if it is still not hard the steel you are using may not have enough carbon to harden.
Step three Tempering.
Tempering is heating the steel to 150-1000 deg F. This will take away the brittleness along with some of the hardness in the steel. The tempering temps will vary depending on the alloy used , size and type of knife being made. For the most part a temper of 300-450 Deg F for an hour is common. Hardness in steel is measured using the Rockwell C scale (RC) this scale ranges from RC30 (unhardened steel) to about RC70 for a med sized knife (6-8” blade) a hardness of around RC58-60 is about right a smaller knife can be harder (RC58-62) and a larger knife should be a bit softer.(RC52-58)
Temper ranges for common some common blade steels
Steel
AS
Hard
300 Deg.
400 Deg.
500
Deg.
1050
RC59
RC55
RC52
RC48
1075
RC64
RC62
RC59
RC58
5160
RC62
RC59
RC56
RC54
O1
RC64
RC62
RC60
RC58
W1
Rc65
RC63
Rc61
RC59
(Temper ranges found online from various manufactures websites)
Basic Metallurgy
Understanding what is happening to the steel during heat treating allows the bladesmith to know when it is safe “to get away with something” and when it isn’t. It also allows the bladesmith to find solutions to the problems that crop up from time to time when working with new steel. Understanding the basics of metallurgy can inform you of what a digital controlled oven is necessary for some steels, and what steels can be appropriate to your equipment.
Steel is defined as iron alloyed with carbon. All modern steels have alloys other than carbon, but all steels must have carbon present to be steel.
Definition of terms:
- Hardness is a measure of a resistance of a material to deformation. For steels, this is measured on the Rockwell C Scale.
- Hardenability is a measure of the steel’s ability to reach hardness, both absolute hardness (at surface) and in depth of hardening (hardness at center).
- Toughness is a measure of the steel’s ability to withstand stress (resistance to shock, flexibility, deformation, etc)
- Each different alloying metal will change the properties of the steel. What each alloy and what different alloys together can do is a lifetime of study. As such, I will not go into further detail other than to say that most alloys are present to change the qualities of the steel (i.e. finer grain, higher hardenability, etc.).
Steel is a crystalline material and can form several distinct structures within that matrix. The first structure is ferrite, which is pure iron crystals in the steel with cementite (iron carbide) binding up the vast majority of the carbon. Ferrite is a body-centered cube of 9 atoms (8 iron atoms at the corners and one iron atom in the center) in which metallic alloys such as nickel can replace one or more of the iron atoms. When steel is heated above its “critical” temperature, a structure called austenite is formed. This is a face-centered cube of 14 iron atoms (again, metallic alloys can replace iron atoms in the structure), which can hold up to 2% carbon by weight between the iron atoms. For the most part, austenite is only present at temperatures above the austenizing temperature (beginning at 1375˚F). When quenched, austenite becomes martensite, which is hardened steel. Martensite is formed when austenite is “frozen” in the quench and is structured as a body centered tetragonal.
The goal of heat treating for bladesmiths is to free up the carbon from carbides and take it to solution with the iron (austenite) then quench to freeze the carbon into solution. In practice this is 3 main steps; normalizing, hardening, and tempering. The purpose of normalizing is to break up carbides, reduce grain size, and allow the ready formation of austenite. This will allow for a shorter soak time at temperature during hardening and finer grain martensite after quenching. Normalizing is defined as heating to the upper transformation point (about 1400-1500˚F) and slow cooling to the lower transformation point about (about 900˚F). Multiple cycles of normalizing can have greater benefits.( this is also called thermal cycling.)
The hardening step consists of heating to above the upper transformation point and cooling within a prescribed rate of time (quench). The length of time between heating and cooling is determined by the alloy (speed of quench). This rate can be found in a TTT (Time-temperature Transformation) chart. When mapped on a TTT chart the hardening curve will look like a nose. So long as the steel is cooled below the tip of the nose within the allowed time, it will harden. The TTT chart also shows the exact upper and lower transformation points, as well as the austenizing point used to generate that curve. After hardening the steel will mostly be martensite with residual carbides, and in the case of the higher-alloy steels there is often some retained austenite as well. Once quenched, the steel is in a highly stressed state. It is very hard, but also very brittle. By tempering (heating between 250-1100˚F) much of the stress is relieved , a portion of any retained austenite is converted to martensite and the overall hardness is lessened. As the hardness is lessened, the brittleness is lessened, and toughness is increased. A second cycle will temper both the original and newly formed martensite and convert more of the retained austenite to martensite. If the temper cycle is repeated 3 times 90% or more of the retained austenite will be converted to tempered martensite. For the average knife steel this isn’t really necessary since low-alloy steels have almost zero retained austenite after quenching. For blades made from high-alloy steels it can be worth the extra effort, and in some cases is actually necessary.
My method is to begin tempering 50 degrees below the finishing temper (i.e. a temper of 375˚F would be started at a temper of 325˚F). Soak at the lower temperature for 1 hour, remove and let cool. Then re-set the oven for 25 degrees higher, temper for 1 hour, remove and let cool. Then complete a final temper at 25 degrees higher, temper for 1 hour, remove the blade and let cool.
Steels come in three classes: hypo-eutectoid (less carbon than eutectoid), eutectoid, and hyper-eutectoid (more carbon than eutectoid). The eutectoid point (roughly 0.75% carbon by weight) in steel is the point at which the amount of carbon present has “saturated” the low temp material but is not yet sufficient for the formation of “free” carbides. In un-hardened steels all of the material should be pearlite, which is a mixture of ferrite (pure iron) and cementite (iron carbide). Below the eutectoid point the material will be a mixture of ferrite and pearlite and above the eutectoid point the material will be a mixture of pearlite and free carbides.
Hypo-eutectoid steels contain between 0.01% to 0.75% carbon by weight. Those steels above 0.4% carbon will harden and tend to be rather tough, though not especially hard. Addition of other alloys can improve hardness and hardenability. The hypo-eutectoid steels are generally easy to forge, grind, and heat treat.
Eutectoid steel is the range right around 0.75% carbon by weight. These steels will harden well and tend to be forgiving when working with them, but do not have the added toughness of hypo-eutectoid steels without added alloys. These are the best steels for beginning bladesmiths due to their forgiving nature and relatively high performance.
Hyper-eutectoid steel is between 0.75% to 1.25% carbon by weight. These steels can yield the highest performance because the excess carbon can form various carbides. They are almost always found with high alloy content, especially such carbide-formers as chromium, vanadium, and tungsten. When treated properly these steels have the best edge-holding and wear-resistance properties, but they are temperamental to work with and react poorly to overheating. Good knowledge of metallurgy and proper control of forging and heat treating temperatures are a must before delving into this group.
Re-polishing
After heat treating regrind the blade using a 120grit belt (remember to keep the blade cool) grind the edge thickness to the finale dimension before sharpening. The thinner behind the edge the knife is the easier it will be to sharpen and the better it will cut, but the weaker it will be. In general a thickness of 0.010-0.025 is appropriate for most knives, skinner or chefs knives should be below 0.010 and large choppers can be closer to 0.030. Once the thickness is established then move to the 220 grit belt and then the 400 grit. (or begin hand sanding at any point) Begin hand sanding starting with one grit lower than the last grit used on the grinder. Sand at an angle to the last grit until and even surface is achieved with no lines left from the last grit, then move on to the next grit. Again at an angle to the last grit sand until all mark of the last grit are removed. The last grit used should run length wise on the blade for the best finish.
For a brighter finish, the blade can be polished using a buffing wheel. Charge the wheel with emery and buff the blade. Clean the emery off with acetone and buff with green chrome.
A word of warning here the buffer is a very dangerous tool , do not present an edge to the wheel or it will catch on the wheel and be thrown. Knife makers have been seriously injured when a blade they were buffing caught and was thrown at them.
Fitting of a Guard or Bolster
Begin by laying out center line on the guard with a scribe. Next, using calipers measure the width and thickness of the tang. Mark the width on the guard centered were the tang will pass through. Then find the center and scribe a line there. Off the center line mark lay out the slot. Use a drill one fractional size under the thickness of the tang. Mark and punch the outside holes, ½ the thickness of the drill bit from the outside lines. Center punch and mark the width of the drill bit from the last center punch mark. Drill out the center punched marks. Use a needle file, to cut away the web of material between the holes. Now file the slot to size using the scribed lines as a reference. Once the tang passes through the slot, file a radius to allow the shoulder of tang to seat fully. A rotary tool or graver can be used to a cut a pocket to seat the blade into, for a cleaner transition. Mark this after the blade is seated, by tracing the blade on the guard with the scribe, then cut away inside the lines. Check the fit often and only remove enough material so that the blade just seats. once fit, the guard can be shaped as desired.
Fitting the Grip
Draw the tang on the handle material. Mark a center line on the side 90Deg. from this. Use a square to continue these lines to the top of the material. Using these lines as guides, clamp the material in a drill press and use a slightly undersized bit, drill out the slot for the tang. Clamp the grip in a vice and carefully heat the tang of the knife to around 900 DEG F. Then use the tang to burn out the slot for a perfect fit. If the blade has been heat treated be sure not to heat the tang past the junction to the guard as this will result in having to re-heat treat the blade. If this is a concern, a bar of steel may be shaped to match the tang and is used to burn out the handle material. Once the tang is fit, draw in the profile on the marked side of the handle. Using a band saw or belt grinder, rough in the shape to these marks (at this point if a pin is included in the design fit that then continue). Repeat for the other 2 facets. Then, round and shape the grip as desired. Check the fit between the guard and handle. Adjust as necessary. Hand sand the handle/grip to about 400 grit for the best finish.
- When hand sanding wood always sand with the grain.
- Lightly wetting the wood between grits will raise the grain and achieve a finer finish
- Adding Pins to the Grip
With the handle profiled to shape and well fit up to the guard, mark where the pins will be placed. Using the proper sized drill bit drill pin holes in the grip (pin holes should be drilled on size IE 1/16” thick pin use a 1/16” drill bit). Now assemble the knife and use a long clamp to keep it together. Use the holes in the handle as a guide to drill the holes in the tang to match. Cut a piece of pin stock 1 inch longer than the width of the grip. Rough up the pin with coarse paper and taper one end. Bend the last ¼-1/2 of the un-tapered end over 90Deg. Insert the pin in the hole and check the fit of assembly.
If the fit is off, carefully file away excess material or use a spacer to restore the fit-up. Leather works well as it will compress and take up any inconstancies when the pin is driven in. Once glued up the leather will be stable and sealed from moisture.
Fitting Antler Handles
Prepare the antler crown or point by using a drill to remove pithy center Antler that is obtained from sheds will generally have less pith than antler obtained from kills. Shape and round the end of the antler., and Remove any sharp projections using a fresh 120 grit belt on the grinder. Hand sand the surface to a grit of 220-420 and buff using a loose wheel and rouge. Use a small file or rotary tool (Dremmel, Fordem, etc.) to relieve the hole for the tang if necessary. (The tang can also be reshaped to fit.) once the tang fits, file the face to meet cleanly with the guard.
Final Assembly
After re-polishing, assemble the knife and re-check all fit ups. Disassemble the knife and lay out all parts in order and in the proper orientation. Mask off the blade with tape (be sure to keep the blade in the proper orientation ) and set the guard back on the tang. Mix up epoxy and coat the tang. Move the guard and get epoxy under it. Next, coat the inside of the grip and anywhere the grip will contact the guard; along with the spacers if any are used, insert the tang onto the grip. Clean off excess epoxy and let set up by clamping in a vice point up. Once the epoxy is set, scrap off any remaining epoxy, Re-polish the grip and seal. Remove the tape from the blade and clean with WD-40, acetone, or denatured alcohol. The blade, guard, and grip can now be waxed or oiled.
Tips
- A brass chisel can be used to clean off excess epoxy that has hardened on the blade without scratching.
- Applying WD-40 to a rag will ease in removing excess epoxy.
- A coat of wax on areas that epoxy shouldn’t be will add in cleaning it off
- Mix a good amount of epoxy. (Mix more than is necessary; better too much than too little.)
- Fill the cavity in the antler almost to the top.
- Spread epoxy on the tang and on any surfaces that contact each other.
- Clamp in a vice point up. do not move the knife until the epoxy is set up.
- Once the epoxy is set, but before it is fully hardened, any remaining epoxy can be more easily removed with a wooden or brass scraper.
Sharpening
The first edge on a newly finished knife should be cut in with the grinder to establish a secondary bevel. Once this is done, the edge can be re-sharpened or further dressed with stones.
On all knives with a secondary bevel (basically anything other than Japanese style work and razors), there are three types of edge: flat ground, convex, and concave (hollow ground edge), Most production knives have a flat ground edge of 15o to 25o. A flat ground edge can be easily re-sharpened and cuts well, Most custom knife makers use a convex edge of the same basic angle of 15-25. This type of edge is just as sharp as a flat edge, but it is stronger, and able to hold an edge longer. It is how ever slightly more difficult to re-sharpen with hand stones. The concave edge is a style that works well for some knives, such as meat cutting knives, that a steel will be used to sharpen but is of limited utility for an everyday knife as it is a relatively weak edge, will dull quickly and is impossible to re-sharpen with hand stones.
As said most custom knife makers use a convex edge, to set this type of edge the blade is ground on the slack belt of the grinder. ( I generally cut the edge with a 120 grit belt making sure to cool the edge frequently. ) Hold the knife edge down at a 10o angle, (as measured from the center line of the blade to the grinder) starting at the base of the blade press in slightly, and take one continuous pass along the whole edge. Cool the blade down and repeat these steps on the opposite side. Continue this process alternating sides until a burr (wire edge) develops all along the edge.
At this point move to a finer belt (220 grit) and continue alternating sides. Then, use 400 grit belt to re-polish the edge. Afterwards strop the edge on the buffer to remove the bur. The knife should be sharp. If the edge is not sharp after buffing, re-cut the edge at a slightly steeper angle and go through the steps again.
For Greater performance of the edge, the edges should be honed with oil or water stones. On a grinder or when sharpened with a dry stone heat is introduced into the cutting edge. The amount of heat introduced is enough to fully anneal the steel for up to 10 microns (a shaving edge is 1 micron or below) even is no color is seen on the blade. By honing away the annealed material using an oil or water stone (the oil or water will carry the heat away from the edge preventing damage) the edge performance will be greatly improved.
Wrapping
There are many different wraps that work well for a knife handle, and many materials that work well for wrapping. Para cord, leather lacing and silk cord all work well.
When planning some styles of wrap is a good idea to drill a hole in the end of the handle to secure the end of the wrap in.
The frap wrap
Begin by cutting off twice what is needed to wrap the grip loosely. Now take one end of the cord and tape it in place along one side of the grip so that is runs from the blade to the butt of the handle. Now tape the other end of the cord, to the reverse of the handle so that is runs from the butt of the handle to the blade. Form a loop with the second end around the top of the handle. Now tightly wind the cord around the handle until you reach the butt of the handle. Form a second loop and pull the extra cord through using the taped end. Pull of both ends to tighten the wrap then use a razor knife to trim the extra cord (cut extra off one of two turns in for a cleaner finish that will not fray)
Overlapping wrap
Prepare the handle by drilling a hole in the end. Then cut two and a half the amount it takes to loosely wrap the grip. Find the center of the cord and make a loop pull the loop tight over the blade side of the grip. Pass the two ends over each other and flip the knife over pull tight and repeat until end of grip. Be sure to pass the same side over the top each time. When you reach the butt of the knife pass the two ends through the hole and wrap one to each side of the hole then tie a knot. Pass the ends of the trough the hole and tie a second knot. trim and glue ends or leave long as a lanyard
Grinders, two wheel and three wheel styles
Recommended Reading:
- Wayne Goddard
- $50 Knife Shop
- Wonder of Knife Making
- Jim Hrisoulas
- The Master Bladesmith
- The Complete Bladesmith
References:
Machinery Handbook – (Pub.) Industrial Press
