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Although there is much overlap with abrasive shaping, cutting here implies severing and separation of relatively large particles from stock to size or shape it with chisel type blades. As such the cutting edges and removed particles are relatively large. Whereas abrasive processes are generally for finishing touches. Most of these processes, utilize individual or multiple chisel type edges or teeth. Each with its own advantages and techniques, the basic functions are slicing, chopping, shearing, chiselling and sawing. The following overview covers the methods, while specific tool types follow after.
Slicing is done by drawing or pushing a very acute, sharp edge through the material using one or more light passes. The edge separates particles on either side, more often raising ridges on the outside. The edge must be honed to assure there are no nicks or irregularities that may produce drag. Often these edges are hollow ground to produce better cutting. Large, circular blade, slicers perform the same function at the meat market.
Chopping generally uses a less acute blade angle and a thrust perpendicular to edge, which splits the particles aside. Examples of single bladed versions ae axes, adzs, sickles, sythes, cleavers and most modelling choppers. With opposing blades, common are nippers, side and diagonal cutters.
Chiselling uses a sharp wedge to split away particles below the surface. The common chisel is usually driven by the heel of the hand, a hammer or reciprocating machinery as in a jack-hammer. Many rotary bits have mutiple chisel blades which cut in succession including metal bur, drill, shaper, planer, router and mill bits. In shaving (not face), a single, handle or housing mounted, blade is pushed through and below the surface to cut away thin slivers as with a spoke shave or a carpenter's plane. With successive chisel teeth, files act as a series of plane blades. In some cases the work piece is moved into a fixed chisel as with lathes.
Shearing comes in two types. Closely akin to chiseling, in the first, a sharp wedge is driven parallel to a surface through a projection from it, splitting it away. More often the force is supplied by a hammer blow. In modelling a chisel blade is pushed along surface to remove unwanted detail.
The second uses two opposing blades, one of which may be stationary. The cutting edges may be right angled or slightly less, with one face parallel to the direction of cut. .These are aligned to closely swipe each other, severing the work between them. Cutting edges may be straight. curved or formed into dies creating punches. Large versions, with one blade fixed, are often used in metal working shops driven by weights, compressed air, solenoids or leverage. More often hand tools, smaller versions usually joins the blades with a fulcrum as in scissors, shears, snips nippers, and paper cutters. Nibblers have smaller blades which may be straight or curved.
Sawing uses successive, narrow chisel, teeth arranged in a linear or circular pattern to produce narrower cuts into or through the body.
Files are similar to wide saw blades with successive teeth which are usually set in rows at an angle. On some a second set of teeth are set at an angle to th first. Rasps have larger teeth for faster cutting. Some have individual teeth in various scattered patterns to reduce clogging. More recently holes have been added in front of the teeth to permit particles to pass through, not unlike a cheese grater. The hardest thing to remember is that files must be lifted on the return stroke to avoid dulling teeth.
CAUTION: All these tools
are dangerous to some extent. Proper protection and care should be used at
all times. Familiarity breeds contempt. I just stabbed my finger while
opening a package in haste. Keep in mind that hand cutting tools are not
intended to cut your hands.
A fair share of these tools have been produced in modelling sizes in both hand and power types. Needs will be determined by your modelling requirements and limited by your budget. The discussions should help in selection and in avoiding wasteful investment in useless items.
HAND CUTTING TOOLS
For most, hand tools will suffice, since almost anything can be accomplished with them, given enough time and effort.
SINGLE OR DOUBLE EDGED KNIVES are probably the most common, but they have many variations that suite some jobs better than others. Again probably the most common are the Xacto or Xpo knives with interchangeable blades. To hold the very wide selection of blades, several sizes of handles are required with several variations of each. In addition to the html to perform the job, comfort in manipulating the blade is quite important.
A perusal of some catalogs will reveal more blades than one would care to use or purchase, but each can perform a function better than others. Used about 90 % of the time is the # 11 blade, which, with a little experience, can be maneuvered in very tight spaces.
In addition there are others that fit particular jobs like scalpels, razor blades, P-cutter, stencil and frisket knives and some heavier duty types. Also there are several accessories for cutting circles and strips.
Although chopping may be accomplished, with a standard knife, even with the aid of a few hammer taps, specialized CHOPPERS can make life easier by setting repeated lengths and angles.
Shearing tools come in a wide variety of forms to fit many jobs. They may be specially designed knife blades or chisels to remove unwanted surface details. Most stationary bladed shears are far too expensive for the average modeller. One exception is the HANDHELD NIBBLER , which has a small shear, about 1/4", driven by a a plier type grip, that is commonly used in auto body work or by sheet metal workers for enlarging holes and trimming.
Fulcrum types are more common. SCISSORS are indispensable for decal work and many light cutting jobs all over the layout, including card stock and thin sheet metal. Many variations exist for odd jobs. NIPPERS and various types of plier cutters are useful for cutting wire, rail, casting gates and many others. PUNCHES can produce clean holes in thin stock, where drilling is impractical.
SAWS come in knife blade form for rough cutting. Stiff backed, razor saws can make fine, straight cuts in almost anything (not rails). Some also come with frames like jeweler's for very fine curved cutout or hack saw for heavier work.
CHISELS come in many forms from various knife blades, turning tools through to very hard metal and stone tools. If your name is Michaelangelo, you may even sculpt Mount Rushmore in a scene. Its use diminishing with the influx of power sanders, the CHISEL BLADE PLANE _ can quickly shave wood for leveling and shaping. Many hobby sized variations have been offered over the years with adjustable blade depths, including spokeshaves.
FILES have been the old standby for shaping and fitting parts. They come in very small to very large sizes , in many cross sections to fit in tiny holes. Riffler files have compound curved ends for producing concave surfaces. As a machinist apprentice , my grandfather had to produce a perfectly square cube of metal with a file, before he was permitted to move on to learning other tools.
POWER CUTTING TOOLS
For those who have more money than time, power tools can increase production rapidly. But mistakes can happen just as rapidly. With some experience the common rotary tool, with its variety of bits, can perform a large percentage of work; but not always as well as some specialized machines.
Although there is a tool, in a housing, similar to the rotary tool type, that has two adjacent serrated, reciprocating blades, as in electric meat carving knives, most of the reciprocating saws do a better job. We have not found any electric choppers, scissors or shears worth the price.
If you do a lot of nibbling, an enblrELECTRIC NIBBLER can speed things considerably . However the die is fairly large and the machine is heavy.
Electric surface shearing, chiselling and filing can be done with several VIBRATOR POWERED, RECIPROCATING TOOLS . With a little experience, very delicate work ca be accomplished in a short time. Some of the work would be very difficult by hand.
SAWS present the widest selection, offering jig, scroll and circular. The band saws are a little too large for model work. Most units have speed controls which permit cutting plastics without melting or sticking or wood without burning. Some very fine blades are available for more delicate work. Most accept abrasive cutters, such as carbides and diamond for cutting hard materials. With their many accessories and guides, they can replace choppers, cutoffs, knives and shears, but at the cost of loss of material from kerf width and clean up of burred edges. Compatibility and standardization of blade sizes presents a problem. Each manufacturer designs to his own standards, which lock you in for replacements.
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