How to cut the steel bar?
One of the first things to do when you decide to build a knife that you have designed is to prepare the bar to begin the contouring of the knife.
It is important to remove all the excess metal to the figure of the knife you want to make and thus obtain a “clean bar” and work with the tape or file (if you do not have a sander) to achieve the desired contour.
This “cleaning” is important if you want to avoid removing mm of steel by hand or with the sander that consume tapes (which cost) and also makes you waste a lot of time.
To do this there are several ways depending on the equipment available.
The 5 main ways to cut the steel bar:
This is the solution used when you start making the first knife and you do not have power tools available.
This is the cheapest solution but also the most tiring.
The hacksaw for iron is found in slightly different versions:
- standard iron hacksaw with bow in steel plate or profile
- short iron hacksaw with thinner blade and shorter length
- mini iron hacksaw for cuts on sheet metal and small pieces
- front hacksaw to be used when there is no space for the headband
- standard metal blades with holes at the ends for attaching to the hacksaw
Always use a stable vice when cutting by hand and in case you need to make a precise cut use cutting guides.
A groove passes blade guides the blade of the hacksaw on the cutting line avoiding any deviation.
The flexible allows you to make cuts quite quickly and with little expense of money for the equipment.
My advice is to take a hose with good power because the steel is hard and the engine is very stressed.
If it is possible to choose a hose with adjustable speed, it can be useful in some cases to choose the speed of the disc, personally with time I bought as well as a more powerful sander than the one I had at the beginning and also one with the speed of the disc adjustable ..
The discs are cheap and with a little practice and experience you can have a good control and remove from the bar the steel that you do not need saving you sanding belts.
Vertical band saw
It is the solution that many professional knife makers use and it is the solution that I use.
It allows precise and rapid cuts.
It is the solution that I recommend if you have an economic availability to face the expense and make many knives.
Beware that there are band saws for wood that have low power and blades not suitable for metal.
Those for metal have more powerful motors and blades for metals, they have a higher cost but really allow you to make precise cuts and in less time.
Attention to safety when using tools of this type.
I personally use a portable band saw for metal and I created a stable support for working vertically and made him the worktop, many makers use this solution, look for a version with adjustable speed. It is really effective and economical.
The one in the following photo is the band saw I use! In addition to the support, I made him a plane that I can easily disassemble and on which I can also lock a guide to make the cuts of the wooden blocks for the handles.
The ideal is to be able to disassemble it easily to have the possibility to change the type of band saw most suitable for steel and most suitable for wood, especially when you have to cut woods for very hard handles such as IronWood or Cocobolo, etc.
Plasma cutting is a process used to cut steel and other metals using a plasma torch.
Today on the market there are different types and affordable prices and allow use with home meters and that allow you to cut steel bars even 12 mm thick which is more than enough for use by Knife Maker.
Also in this case there are quality products that allow precise cuts.
It is a tool that needs to have a compressor in combination because of its principle of operation that needs a gas and in the case of the compressor oxygen.
It’s the solution I’m using now in my lab.
Principle of operation of plasma cutting
Plasma cutting is a thermal break process in which a plasma arc is forced through the torch nozzle.
Such an arc, which is formed when electricity flows from the unmelted electrode (cathode) to the workpiece (anode), is used to cut electrically conductive materials.
We speak in this case of transferred arched torches.
On the contrary, when it is the nozzle that performs the function of anode, we speak of untransfered arc torches.
Over the professional plasma arc, the gases are partially dissociated and ionized, making them electrically conductive.
Thanks to the high energy density and temperature, the plasma can expand and move towards the workpiece up to three times the speed of sound.
Through the recombination of atoms and molecules on the surface of the workpiece, the absorbed energy is immediately released, intensifying the thermal effect of the plasma arc on it.
Combining the process with the high kinetic energy of the gas, plasma cutting acquires a very high cutting speed, which will vary depending on the thickness of the material.
To start the cutting process, a pilot arc is initially ignited between the nozzle and the electrode, applying a high voltage.
This low-energy pilot arc is intended to prepare the gap between the plasma burner and the workpiece by causing partial ionization.
When the pilot arc comes into contact with the workpiece, the main arc of the plasma ignites through an automatic increase in power.
Due to the thermal energy of the arc and plasma gas, the metal material melts and partially vaporizes.
Fusion is expelled from the shear groove – called a kerf – due to the kinetic energy of the plasma gas.
Unlike oxyfuel, in which about 70% of the thermal energy is produced by the combustion of iron, in plasma smelting the energy needed to melt the material into the kerf is produced only electrically.
The ones I am talking about are clearly with the principle of oxyfuel since they are machinery for domestic use and not industrial.
In plasma cutting, in addition to the melting temperature of metals, their boiling point is sometimes also exceeded: most metal vapors, for example Titanium, are toxic and do not have to be breathed.
This involves working in well-ventilated places or under an extractor hood, and for larger machines it makes an adequate flue gas disposal system necessary.
The high voltage present in a system and the risks associated with the use of current sources of these types must also be taken into account.
Like all electric arcs, the plasma arc also produces ultraviolet light radiation from which one must protect oneself with the use of special devices (masks, glasses with suitable filters and appropriate clothes).
The arc is also a source of noise, a source of electromagnetic radiation that can interfere with devices such as “pacemakers” especially if equipped with high-frequency sources.
Conclusion: do not underestimate the risks of using these devices, use protections, read well the ‘safety’ chapter of the use and maintenance manual that manufacturers are required to provide with the product, in the language of the country where the plant or machinery is sold (valid in Europe)
It is the option that uses those who make large productions and buy steel sheets and not bars and this allows him to save money on the material and through laser cutting can have multiple shapes all the same already shaped and with the punctures provided.
Great repeatability and speed.
Clearly they turn to external cutting suppliers who offer the service or those who have large sales volumes buy the laser cutting machine but it has significant costs.
Safety in cutting steel bars
Safety is essential in all cutting operations.
It is essential to always wear these operations during these operations:
- goggles or protective masks,
- anti-cut gloves and
- the mask with dust filters.
Ps. If you use the sander it is essential to have a good grip to lock the piece solidly.
Cutting the steel bar is a stage that some people find pleasant and others less so.
It is important to do this phase well before the contouring that gives the shape of the knife because in addition to speeding up the work phase it allows you not to consume the abrasive belts unnecessarily.
My advice is to devote the right time to this stage and if you have more knives to do since it is an operation that “dirty a lot” especially if you use the flexible to make multiple knives together to clean once.
The hose remains if you don’t have equipment the cheapest choice to start but if you have the economic option the metal ribbon saw (attention to metal) remains a great tool that allows you to make precise cuts.
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