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Steel is an alloy of iron and carbon. These two elements are combined in the molten state and form the new material when it solidifies. This is done by dissolving the alloying elements, adding them to molten iron and casting this into an ingot. The ingot is then rolled into shape while still hot and allowed to cool, producing so-called wrought steel.

Powder Metallurgy

Current state-of-the-art knife steels are formed using a complex process known as powder metallurgy. This involves instant cooling of the alloy using liquid nitrogen to form a powder which is then purified and re-shaped. This prevents formation of the large carbide particles which form when an alloy is allowed to cool slowly.

Further heat treatment and quenching is performed to harden the final article. The resultant crystalline structure of the steel particles gives a honogenous, high quality steel. CPM S30V steel produced by Crucible Materials Coporation, USA. , is formulated to promote the formation of vanadium carbides, which are harder and more effective than chromium carbides in providing wear resistance. CPM S30V is substantially tougher than other high hardness steels such as 440C and D2, and its corrosion resistance is equal to or better than 440C in various environments. This steel is used in many Spyderco Knives for example; Spyderco Military Knife; Spyderco Mini-Manix Knife c101; Spyderco UK Penknife C94GP .

The standard blade steel used in Buck Knives is 420HC. This is a high carbon version of standard 420 martensitic stainless steels which is further hardened during Buck's exclusive heat treatment process. The finished blade steel has an optimum combination of wear resistance and corrosion withstanding properties.

Properties of Steels

Corrosion Resistance: The capability of the steel to resist damaging reactions with the environment. This is increased by addition of chromium, copper, molybdenum or nitrogen.

Edge Retention: The ability of the steel to withstand abrasion and wear. This is improved by adding carbon, chromium, manganese, nitrogen or vanadium.

Hardness: This is proportional to the strength of the steel, and measures resistance to deformation or penetration. Improved by carbon, chromium, cobalt, molybdenum, nitrogen or phosphorous.

Mohs Scale of mineral hardness: This characterises the scratch resistance of various materials by comparing the ability of a harder material to scratch a softer material. For example, talc measures 1, pure gold measures 3, hardened steel measures 7 , diamond measures 10. Alumina Ceramic sharpening stones manufactured by Spyderco, measure 9 on this scale. These are manufactured in USA, in a process which combines a bonding agent with alumina particles. Alumina particeles are essentially synthetic saphires measuring 15 - 20 microns. The Spyderco sharpening stones are shaped and kiln-fired at 1649 degrees centigrade. Medium grit and fine grit stones are supplied with the Spyderco Tri-Angle Sharpmaker 204MF. These have the advantage of lubricant-free sharpening, although after prolonged use will need cleaning to remove microscopic steel particles adhering to the stone. The sharpening effectiveness is gradually reduced as the stones become loaded with steel. They are easily cleaned by washing in fresh water and scrubbing with powdered abrasive and a scouring pad to remove steel residue from the open cell structure.

Hardenability: The ability of a steel to be harded by a heat tretment process. Improved by adding manganese, molybdenum or tungsten.

Heat Treating: A process which changes the physical properties of the metal by controlled heating and cooling to certain temperatures and limits.

Quenching: Rapid cooling of steel which has been heated to a high tempertaure, by soaking in air, oil or water. This process alters the crystalline structure, increasing hardness by forming martensite.

Austentitic Steel: The basic steel structure state being an alloy uniformly dissolved in iron

Martensitic Steel: A particular hard and brittle form of steel with a certain crystalline structure.

Tempering: A process of slightly softening and relieving stress in the steel by slow, steady heating to just below re-crystallisation temperature. This is followed by a slow, steady cooling phase.

Toughness: The ability of a material to withstand shock or impact, this is improved by addding chromium.

Classification of Steels.

Steel is classified according to the elements used in the production which alter the physical properties of the steel.

Carbon Steels.

These contain varying amounts of carbon, up to 1.65 % of manganese and 0.6 % of copper. There are 3 types of carbon steels. Low carbon steel contains 3 % or less carbon; medium carbon steel contains 4 - 8 % and high carbon steel (the type most commonly used in knives) contains more than 9 % carbon. The addition of carbon increases edge retention and raises tensile strength. It also increases hardness and improves resistance to wear and abrasion.

Alloy steels.

May contain specific percentages of vanadium, molybdenum or other elements as well as larger amounts of manganese, silicon and copper than do conventional carbon steels. Vandium is used to increase wear resistance and toughness and limits the grain size of the crytalline particles. Molybdenum increases strength, hardenability and toughness of steel. It also improves machinability and resistance to corrosion , helps retain fine grain size and is often used in high speed tool steels in place of tungsten. Manganese increases hardenability, wear resistance and tensile strength. In molten metal it helps to de-oxidise and de-gas to remove oxygen, in larger quantities it increases hardness and brittleness. Silicon increases strength and also serves to de-oxidise and de-gas to remove oxygen in molten metal. The addition of copper helps to increase corrosion resistance.

High Strength Low Alloy Steels (HSLA Steels)

These are low cost versions of regular alloy steels, containing only small amounts of the expensive alloying elements. Howvwer, they are specially processed to have greater strength than carbon steels of the same weight.

Stainless Steels

These contain a minimum of 12 % chromium, which provides a much higher degree of rust resistance than carbon steels. The amount of chromium needed also depends on the other elements used in the steel. Chromium increases hardenability, tensile strength and toughness and provides wear and corrosion resistance.

Tool Steels

These contain tungsten, molybdenum and other alloying elements that give them extra strength, hardness and resistance to wear.

Exotic Steels

Although generally accepted as steel, these are not technically steels, for example, H1, ZDP-189, Telonite and Titanium

References:

Spyderco Product Guide 2008. Spyderco Knives, 820 Spyderco way, Golden, Colorado 80403, USA

Crucible-Data Sheet. Crucible Materials Corp. USA

Buck Knives. www.buckknives.com

There are many geometrical variations of blade thickness, blade point, belly, spine, edge angle and grind and each variation has trade offs between cutting ability and strength.

The belly of the blade is the curving portion under the point which may be absent in Tanto or Sheepfoot blades. Blades with more belly are optimised for slicing rather than piercing. An optimal piercing blade with a strong and easily controlled tip may have little or no belly, being less useful for slicing.

The angle between the edge and the handle plays an important part in the knife ergonomics. The edge may not be parallel to the spine of the knife and may have a positive or negative included angle. A positive angle provides more belly and edge, whereas a negative angle provides a sharper point. A variation of this is when the blade and handle are joined at an angle to further enhance slicing ability.

The point of the blade is strongest in the Tanto design, made popular by U.S. manufacturers in recent times, as the spine is full thickness all the way to the point. For a sharp point, the steel needs to be as thin as possible such as in the dagger blade. For maximum control of the point, the point of the knife should be in line with the user's hand, below the level of the spine of the blade.

The thickness of the blade alters the strength and cutting ability. The objective is to have as fine an edge as possible, yet maintain the strength of the edge and the blade in general. Different types of grind may be applied to the blade. A flat grind will maintain the strength of a thin blade, whereas a hollow grind will provide a thin edge in a thick blade. The combination used depends on the function of the knife, whether intended for fine delicate cutting, or for heavy weight chopping and levering.

The edge thickness is determined by the thickness of the blade spine, the blade shape and the grind type. The primary bevel may be flat, hollow, convex, chisel or sabre ground. The cutting edge is formed by a secondary bevel and this may be altered by the knife owner by re-sharpening, to provide a thinner or thicker edge.

The hollow grind blade has a biconcave cross section and has the advantage of a very thin edge which is easy to re-sharpen.

The chisel grind edge is ground on one side only, with single sided bevels. Re-sharpening only needs to be performed on the bevelled side of the blade, with simple burr removal on the un-bevelled side. This provides a thin, strong edge which is easy to maintain, although it is inaccurate when cutting due to the assymmetry of the edge.

The Sabre Grind edge has a flat primary bevel starting near the middle of the blade which gives a strong edge for chopping and hard use.

The Flat grind has a V-shaped cross section, is stronger than a hollow grind, though less strong than a sabre grind. The Spyderco Military Lock Knife C36 has a 4mm thick blade spine and full flat grind primary bevel, with 20 degree secondary bevels on each side.

The convex grind has a biconvex cross section, without a secondary bevel and is formed using a flat belt grinder. This produces a blade with a strong point and strong edge although the bevel cannot be easily changed.

Serrated Edge Blades - A serrated edge increases the effective cutting edge length by up to 24%. The sharpened recesssed curve has more linear cutting surface than a straight edge. Edge retention is also greater because cutting is started by the serrations' tips, easing the workload on the recessed edges, and protecting the sharp inside cutting curves which wear less over time.

Spyderco Knives 'Spyderedge' is a secondary bevel, ground on one side of the blade only and may be re-sharpened using the pointed angles of ceramic sharpening stones.

Some of the blade shapes in popular use are outlined below:

Recurved Blade

The belly of the knife is 'S' shaped and presents a greater edge length to the material being cut. Although ideal for slicing, recurved blades are almost impossible to re-sharpen without specialised equipment.

Sheepsfoot Blade Shape

Sheepsfoot blades do not have a point, as the spine curves down to meet the edge and these are often used in rescue knives. Emergency procedures may involve cutting through a jammed seat belt in the aftermath of a car crash. Clothing may also have to be cut through in order to free a victim or to gain venous access. Cutting through fibrous materials in such close proximity to the casualty is much safer if the knife being used does not have a sharp point.

Clip Point Blade Shape

The tip is formed by a concave or straight cut out portion of the blade spine which is the 'clip'. The upper false edge usually has a bevel, making the point sharper. The point of the blade is lowered bringing it closer to the midline of the blade. The Buck Ranger B112 Model features the clip point with a bevelled, concave false edge on the back of the blade tip.

Drop Point Blade

The tip of the blade is lowered by a convex, unsharpened curve of the blade spine, providing a stronger, though less sharp tip. The Spyderco UK Penknife C94GP has a full flat grind drop point blade with a secondary bevel of 20 degrees on each side of the edge.

In some cases, a portion of the blade spine near the tip may be ground off, creating a 'Swedge' or unsharpened false edge. This removes weight from the blade, improving balance and penetrative properties.

The Spyderco Police C07 model has this type of weight reducing swedge near the blade tip. With a 3 mm thick spine, the hollow grind primary bevel gives a relatively thin cutting edge.

Tanto Blade

Re-popularised in recent times by U.S. knife makers, the tip of the blade is in line with the blade spine. The sharpened front edge meets the long edge at an acute angle, forming a second point where the two edge join. This creates an incredibly strong point, as the blade spine is full width until very close to the point.

Spear Point - The point is located at the midline of the blade and the blade spine may be sharpened on both sides near the tip.

Trailing point - The point is the same height or higher than the spine of the blade, providing an enlarged blade belly for slicing or skinning.

Hook Blade - A concave shaped blade found in pruning knives, marine and rescue knives. Cutting is improved by starting the cut at the edge near the handle and pulling the knife inwards, thus forcing the material being cut closer to the edge near the tip.

Dagger Blade - Tapers to a thin, sharp point, with both edges sharpened and ground in from the exact midline of the blade.

Blade Steels - The type of steel used determines the toughness, edge holding ability, corrosion resistance and ability to resharpen the blade. Steel with low carbon content has a higher resistance to corrosion, whereas high carbon content provides greater toughness and easier re-sharpening. (See article on blade steel types)

Tool Logic Multi-Tools Tool Logic improves design of Pro 2 Series multi tools

The latest incarnation of their highly popular lock knife / firesteel / torch combo has a major design improvement.

Regular users of this tool are familiar with the removable LED torch which is housed in the watertight compartment of the handle. The torch is activated by rotating the torch head anticlockwise to switch on and clockwise to switch off. A convenient one handed operation when holding the knife with torch in situ. Previously this relied on a tight fit, preventing the body of the torch from turning whilst rotating the knurled aluminium torch head.

Over time, however the the torch would loosen, causing difficulty when activating the torch light. The new design has a hexagonal torch body fitting into a correspondingly shaped water tight cavity in the knife handle. As before, the seal is maintained with a rubber 'O' ring. This makes the quarter turn on / off switch now 100 % positive. In addition a thicker stronger firesteel is provided. The only drawback is the lack of backwards compatibility in this model. Owners of the old Pro 2 knives will no longer be able to replace the torch / firesteel in those models, as the new hexagonal torch does not fit the old knives...

Cycling Gloves

As a regular mountain bike rider, gel padded cycle gloves are an essential piece of kit for me. There are many different brands on the market made from different textiles. 'Amara' is a durable synthetic textile often used in the outer palms of cycling gloves. Open cell foam padding is also used as the padding material in the outer palm. Effctive padding here is crucial to prevent possible nerve damage in the cyclist's hands. A decent thickness of gel padding is found to be more effective as a shock absorber in the outer palm. Open cell foam padding should also be placed in the inner palm underneath the inner lining. A cotton inner lining is necessary to allow ventilation and prevent excess sweat build up. A natural leather palm is probably preferrable to synthetic Amara materila as the outer palm material.

Goat skin leather is a cheap commodity in many countries and makes an ideal palm material for cycling gloves, due to its soft, pliable nature. Active Gel Cycling Gloves have a palm made of soft goat skin leather. The inner lining of the palm is a made of smooth cotton material. The padding consists of 3 gel inserts which acts a shock absorber on the palm of the gloves. The backing material is made of stretchable, so called 'Fourway Material' . A stretchable, lightweight material is necessary as the backing material and 'Fourway' or Lycra is often used. The back of the thumb is made of a double layer of cotton towelling, an absorbent material, unlike the 'Fourway' used in the backing. This enables the towel-clad thumb to be used to wipe away sweat or nasal secretions.

Cycling and the risk of nerve damage

During a long bike ride, the localised force exerted in one area of the palms by the pressure of the handlebars can affect the median nerve, which passes along the palm of the hand.
Prolonged pressure on the median nerve may cause symptoms of a burning sensation in the hands and numbness in the fingers. Palm protection is an important factor in choosing bike gloves. "Active Gel" gloves have 3 gel inserts designed to absorb the forces directed towards the palms of the hands. Total thickness of 5 mm of padding is achieved with a 3 layer construction. On the inside is soft cotton material, with exterior palm of pliable goat skin leather. Sandwiched in between is the gel padded layer.

Gel padded gloves are equally useful for wheelchair or crutch users. Using gloves helps prevent friction damage to the skin as well as long term median nerve damage. Likewise use of gel padded gloves is recommended for weightlifting , rowing and other gym activities where there is prolonged pressure on the palms.

Choosing the fit.

Loose fitting gloves are preferrable to tight fitting ones. Over tight gloves may compromise finger circulation and cause discomfort. Hands may swell slightly during cycling and gloves should allow free range of movement of your thumb. An adjustable velcro strap allows a comfortable fit to be achievd.The backing of each glove is made of a lightweight and flexible 'Fourway' material, as this prevent excess hand sweating and allows free movement. In addition, "Active Gel" gloves feature Terry Cloth backing on the thumbs, to use in wiping sweat off your face. Because of the somewhat delicate nature of the materials, when taking off your gloves, care should be taken. It is important not to simply tear them off, pulling them inside out, as this may damage the stitching. Instead, pull them off from the fingers, this way preventing any tears to the stitching.

National Cycling Network

Sustrans is a charity that promotes cycling and has developed the National Cycling Network using Government Grants and Lottery funding. Established over the last 10 years , the National Cycling Network now passes within 1 mile of half of the population, using pedestrian routes, disused railways, minor roads, canal towpaths and traffic calmed routes in towns and cities. More information can be found online in WIKIPEDIA including all completed regional sections of the network.

The Government Cycle to Work Scheme

Introduced in 1999 as part of the Government Green Transport Plan, this scheme allows basic rate taxpayers to receive a 40 % reduction in the cost of buying a bicycle. A 50 % saving is available to higher rate taxpayers. The employer is allowed to provide employees with a bicycle to cycle to work as a tax free benefit. And this can also be used for leisure cycling, provided it is used to cycle to work from time to time. Tax benefits apply to the cost of the bicycle and cycling equipment. The scheme is operated through service providers and involves the employer purchasing bicycle and equipment from the provider. Employers are entitled to reclaim VAT from the purchase. The employee then leases the equipment for a year, paying this from pre-tax income. At the end of the year this can bought by the employee at a cost of 2.5 % of the original cost.

Buy Cycling Gloves

August 2007 - Lifeboat Crews Supplied with Spyderco Atlantic Salt Knives

The Bude inshore lifeboat crew now include Spyderco's Spyderco Atlantic Salt Knife in their essential kit. This was chosen over the less costly Spyderco Rescue 93 mm. Knife which had, unsurprisingly started to show signs of corrosion after exposure to sea water. The crucial difference between the two knives is the H1 steel used in the Atlantic Salt's blade. A precipitation hardenend alloy with 0.1 % nitrogen instead of carbon, H1 steel has edge holding abilities comparable to premium carbon steels. In addition, non-rust internal components are used in the Salt Series of knives, including pocket clips made of titanium.

Blade Style

Rescue Knife designs often feature a modified Sheep Foot or Wharncliffe style blade. Emergency procedures may involve cutting through a jammed seat belt in the aftermath of a car crash. Clothing may also have to be cut through in order to free a victim or to gain venous access. Cutting through fibrous materials in such close proximity to the casualty is much safer if the knife being used has a blunt or rounded tip.

The Emerson Knives US Navy Search and Rescue Knife (SARK) has a partially serrated blade with a Wharncliffe style blade, similar to the Eickhorn Pocket Rescue Tool PRT XII. The Spyderco Atlantic Salt and Rescue 93 mm knives are blunt-ended Sheep Foot style blades A serrated edge increases the effective cutting edge length by up to 24%. The sharpened recesssed curve has more linear cutting surface than a straight edge. Edge retention is also greater because cutting is started by the serrations' tips, easing the workload on the recessed edges, and protecting the sharp inside cutting curves which wear less over time.

Seat Belt Cutter

A Secondary blade or seat belt cutter is a safety feature for use when cutting in close proximity to a living person. This may involve cutting through a jammed seat belt restraint or cutting through clothing. Incorporated into a slot in the handle it is used by positioning the fixed material within the slot and pulling the knife in the opposite direction. The 'Rescue Hook' is a design variation where the blade tip has a blunt outer surface, and a sharpened inner crescent shaped edge. Many manufacturers have their own variants of this design. An example is the Eickhorn Pocket rescue Tool PRT XI

One-Handed Opening

The Emerson wave Hook, invented by Emerson Knives provides a solution to the one-handed opening of a folding knife. This opens the blade when the knife is withdrawn from a pocket. Grasping the end of the handle between forefinger and thumb, the knife is drawn out and backwards. The hook protruding from the blade back catches on the pocket and opens the blade. If the knife is drawn out and backwards in one complete motion, the blade opens fully to the locked open position. Another option is the thumb stud, which can be right or left handed or ambidextrous. This may be permanently riveted to the blade as most ambidextrous thumb studs are, or removable to allow for right or left handed positioning. The so-called ambidextrous thumb lug is attached to the back edge of the blade instead of the flat surface of the blade. The disadvantage of having a thumb stud or lug attached to the blade is that it may interfere with the cutting activity when using the knife. If the thumb stud is positioned too far along the blade it will compromise the blades usefulness, whilst if positioned too close to the handle, it will be difficult in practical use.

The blade opening, thumb hole-pull also allows one-handed opening. The cut-out portions of the blade are different shapes depending on the manufacturer. There are many variations such as the Spyderco Round Hole, the Tool Logic oval hole, the Byrd Knives, tear-drop shaped hole and the Leatherman oblong shaped thumb hole pull. The size of the thumb opening hole in Spyderco knives is increased to 14 mm diameter in military and rescue models, an allowance for gloved hand-use. Thumb hole sizes in Spyderco knives varies from 11 mm in the Lava and Kopa knives, 12 mm in the Police knife, 13 mm in the UK Penknife and 14 mm. In the Assist and Atlantic Salt knives. The Spyderco Assist Knife has an added 'Cobra Hood', which is a raised border along the top edge of the spine cusp above the thumb hole. The 'Cobra Hood' makes blade opening easier when the thumb is not fully engaged in the thumb hole, for instance when the user is wearing gloves. Holding the knife in the palm of the hand at the base of the fingers, grasp the handle with the tips of the fingers, place the pad of the thumb in the thumb hole, then slide the blade away from the handle using the thumb.

Window Puncher / Glass Breaker

The window puncher or glass breaking stud is a pointed, cylindrical protrusion mounted on the handle, usually at the opposite end to the blade pivot. It is made of tungsten carbide, effective at breaking toughened glass due to its diamond-hard nature. The Spyderco Assist knife has a retractable carbide tip, which is activated by squeezing the blade into the handle. Handy Niknaks Website