Tools And Implements

In some structural work, cast iron is used extensively on account of its cheapness; but for certain classes of work, cast iron is not suitable, and wrought iron is employed almost exclusively; as, for instance, the -work of elevator enclosures, light railings, lamp brackets, and work of a like character.

Ornamental wrought-iron work may be divided into two general classes; namely, that which requires to be fashioned while hot, and lighter work which is manufactured from cold materials. In each case the original material is in the same form - long bars of varying widths and thicknesses, which are worked with vise and pliers, are forged with hammer and anvil into any desired shape. The dominating feature of some designs is frequently the repetition of similar scrolls or rings; and when there are a number of these, it is necessary that they should be produced rapidly and exactly alike. In making any small scroll of light iron, the first and most important step is the forming of the small quirk, or curl, at the center, and the method and machine for doing this is shown in Figs. 32 and 33. The tool employed is of a very simple character, and consists of a fixed cam a, over which the clamp, or die, b fits closely and is pivoted at the other end; the spring c keeps the die clear of the cam, and the lever d forces it into place. In Fig. 32 the lever is thrown back to allow the clamp to be pressed open by the spring c. The bar, the end of which is to be bent, is introduced between the cam a and the clamp b. The lever is then pulled forward, and the die is forced against the cam, and the beginning of the scroll is formed. The bar is then brought around to the position shown in Fig. 33, and the first convolution of the spiral thus completed.

Fig. 33.

31. The bar is now placed in the machine shown in Fig. 34, and the remainder of the scroll is formed. This machine consists of a shaft a, on which a screw thread is cut, and over which is coiled a steel spring b. On one end of the shaft is a crank or handle, and on the other end is the disk e carrying the coil or volute f, which forms the die or pattern for the rest of the scroll. This plate and volute are detachable, so that different sizes a scrolls may be formed on the same machine.

Fig, 34.

The bar, having had the first convolution of the scroll formed as already described, is now placed in the machine, as shown at h. The lever g is pressed against it to hold it in close contact with the volute f, and the disk is revolved until the scroll has assumed the proper number of convolutions. As the shaft turns, the screw thread causes the disk to advance, and the bar h is coiled evenly in one plane, instead of conically, as might appear from the spiral on the disk. When the shaft has reached the point where the proper number of revolutions has been attained, a catch releases the nut from the screw thread, and the spring b throws the shaft and disk back to their original positions, and releases the completed scroll, which is now cut off the bar, and another one prepared in the same manner. With such appliances one man can make from 300 to 000 scrolls a day, according to their size and weight; but where only a few are required it is usual to make them almost entirely by hand, for which tools similar to those shown in Fig. 35 are used, the operation being so simple that description is not necessary.

Fig. 35.

32. As it is more economical to have special machines for the manufacture of scrolls in quantities, the same applies to the twisting of flat bars, and for this purpose the appliance shown in Fig. 30 is used. This apparatus consists of a fixed upright a, with a socket to receive the pipe b, the other end of which rests in the movable upright c. The latter is arranged to travel along the bedplate by means of a threaded shaft d, so that the length of the pipe b may be changed to suit the length of the twist required to be produced. The bar to be twisted is passed through the pipe and the slot in the lever e until in proper position, and the slotted piece f is dropped into the pocket, as shown at (b). If the length of the pipe is such that the distance between the lever and the slotted piece is of the desired length for the twist, then the bar being held at these two points and prevented from revolving independently, the lever is wound around as many times as is necessary to produce the required twist. The greater the number of turns, the closer will be the twist. The piece f is made loose and dropped into place, so that it may be easily lifted out when the twist is complete, and the finished bar drawn out without twisting it through the slot, as would be necessary if the slots were permanently fixed in each end. The pipe b merely acts as a guide to prevent the bar from bending in a lateral direction when the twist is of considerable length.

Fig. 36.

33. This machine is for making a regular twist, as shown at (c), but another form of twist in common use, especially in light grille-work, is made by giving the bar a series of half turns, as shown in Fig. 37. The bar is dropped into two slots, as shown, one of which can be adjusted by means of a long screw underneath the bedplate, so that the length of the part to be twisted may be regulated. It is then grasped between these slots by the loose clutch, and given a half turn, producing the result shown at (b). If the bar is to form a part of a sqaure grille, as shown at (c), there will be a number of these twists to each piece, and the distance from center to center must be marked out before the twisting is commenced. If the quantity required should be great, it might be advantageous to make a set of fixed pockets set to the proper centers, so that six or more turns could be made without lifting the bar. The foregoing are a few of the tools used in the manufacture of light grille-work; where, however, this class of work is produced to any great extent, there is a constant demand for new tools to meet the requirements of special conditions, but these tools cannot be bought and must be made. It would be impossible to provide for the manifold variations that are likely to occur; but, apart from these special tools, those that are here illustrated are always in demand, and supplement the general machines, such as drills, punches, lathes, etc.

List of agricultural machinery

Traction and powerTractor
Crawler tractor / Caterpillar tractor

Soil cultivationRotavator
Cultivator
Cultipacker
Chisel plow
Harrow
Spike harrow
Drag harrow
Disk harrow
Plough
Power tiller / Rotary tiller / Rototiller
Spading machine
Subsoiler
Two-wheel tractor
Stone picker (rock picker)
Rock windrower (rock rake)

Planting
Broadcast seeder (alternately: broadcast spreader or fertilizer spreader)
Planter (farm implement)
Plastic mulch layer
Potato planter
Seed drill
Air seeder
Precision drill
Transplanter
Rice transplanter

Fertilizing & Pest Control
Fertilizer spreader, see broadcast seeder
Terragator
Manure spreader
Sprayer



Irrigation
Center pivot irrigation
Drip irrigation
Hydroponics


Produce sorter
Weight Sorter
Color Sorter
Blemish Sorter
Diameter Sorter
Shape Sorter
Density Sorter
Internal/Taste Sorter

Harvesting / post-harvest
Beet harvester
Beet cleaner loader
Bean harvester
Cane Harvester
Carrot harvester
Chaser bin
Combine harvester
Conveyor belt
Corn harvester
Cotton picker
Fanning mill
Farm truck
Forage harvester (or silage harvester)
Gleaner
Grain cleaner
Grain dryer
Gravity wagon
Haulout Transporter
Over-the-row mechanical harvester for harvesting apples
Potato digger
Potato harvester
Rice huller
Sickle
Sugarcane harvester
Swather
Winnower

Hay making
Bale mover
Bale wrapper
Baler and Big Baler
Conditioner
Hay rake
Hay tedder
Mower
Loader wagon, Self-loading wagon – used in Europe, but not common in USA


Loading
Backhoe
Front end loader
Skid-steer loader


Milking
Bulk tank
Milking machine
Milking pipeline

Other
Allen Scythe
Grain auger
Feed grinder
Grain cart
Conveyor Analyzer
Chillcuring

Obsolete farm machinery
Steam-powered:

Stationary steam engine
Portable engine
Traction engine
Agricultural engine
Ploughing engine
Steam tractor
Binder
Flail
Hog oiler
Reaper
Winnowing machine/Winnowing-fan
Threshing machine
Drag harrow

Agricultural Tools

There are a number of appropriate technology principles that specifically concern agricultural tools. Such tools should be produced within the country, in part simply because of the large numbers involved. They must be repairable at the local level. With much of agriculture characterized by short intense periods of activity, farmers cannot afford delays caused by equipment failures.

The FAO book Farm Implements for Arid and Tropical Regions includes a list of important general principles for appropriate agricultural tools, some of which go beyond the general criteria for appropriate technology.

“Such tools should be:

a) adapted to allow efficient and speedy work with the minimum of fatigue;

b) not injurious to man or animal;

c) of simple design, so that they can be made locally;

d) light in weight, for easy transportation (there are also considerable advantages when threshers, winnowers, and machines such as coffee hullers can be easily moved to where they are needed;

e) ready for immediate use without loss of time for preparatory adjustments;

f) made of easily available materials.”

Appropriate agricultural tools and equipment should contribute to the broad objective of increasing the viability of the small farm. Where small farmers are currently employing traditional technologies that are inefficient, they often cannot improve this technology because of the leap in scale and capital cost to commercially available equipment. It is therefore the goal of intermediate technology proponents to help fill this gap with good quality tools and equipment that are affordable and suited to the scale of operations of the small farmers.

There is a tendency for equipment development and commercial firms to concentrate their energies on tools that are affordable only to the wealthier farmers. This happens in part because of a focus on what technically could be done, without attention to financial constraints faced by the typical small farmer. Contributing factors include the inappropriate application of industrialized, extensive farming strategies to small intensive farming communities, and the failure to include the small farmer in the process of identifying helpful new technologies that can truly fit into the existing farming system. The result is usually either outright failure of innovations to attract interest or the consolidation of landholdings by wealthier farmers taking advantage of the technology newly available. The position of tenant farmer may become worse, and that of small farmer in general is not improved. Appropriate technology advocates must be careful to avoid repeating these mistakes.

The degree of concentration of land ownership is a key factor in determining if there are opportunities available for appropriate technology strategies in a community. Agricultural technologies developed with and for the smallest farmer can certainly strengthen the viability of their farms. But if most families have no land at all, land reform and the establishment of rural industries may be far more important steps in a positive community development program than the improvement of agricultural tools and equipment.

In most of Asia and much of Latin America, farms are quite small. Under these conditions, most mechanized equipment will not increase the amount of food produced, but will only decrease the amount of labor required. Productivity per acre or hectare may in fact decline if these large tools require extra space to maneuver and wide lanes to drive or roll over. The appropriate tools under such circumstances, even if supported by unlimited resources, would be very different than those used in the United States, where the amount of cultivated land per capita is relatively large.

From the national perspective, support for communities of small farms should bring significant benefits. Whereas it has been widely assumed that only the large farm could efficiently increase national food production in the struggle against hunger, mounting evidence from many countries indicates that the small farm has higher yields per acre and plays a crucial role in the distribution of food. Small farms also make the best use of national capital resources:

“To maintain … a rational growth of capital in a low-income economy, small farms are better suited than large ones, for the small farmers do not experience the same pressure to substitute capital for labor; no one wants to mechanize himself out of a job.” (Folke Dovring, in Agricultural Technology for Developing Nations).

People interested in improving local agricultural equipment should be looking for technologies that accomplish one or more of the following:

1) Remove labor bottlenecks in the agricultural calendar that are limiting production (e.g., short periods of time when all available labor is fully employed, such as during planting or harvesting).

2) Replace or speed up activities that are extremely inefficient in the use of time (e.g., traditional hand-milling). This can free time for more productive activities.

3) Increase the productivity of land (e.g., with irrigation weeding, natural fertilizers)

The effectiveness of efforts to create relevant new tools can be increased by.concentrating on some key agricultural activities. Irrigation is the biggest single factor in increasing crop yields. The successful widespread use of hand pumps for small-plot irrigation in Bangladesh is a very interesting development. Water-conserving irrigation methods in arid lands have similar potential benefits. Animal-drawn plows, cultivators and carts tend to satisfy the equipment needs of small farmers using both intensive and extensive techniques. Good quality hand tools should not be overlooked. Equipment that helps to conserve expensive fertilizers and pesticides will reduce cash costs and have beneficial environmental effects. Greenhouses can conserve water, and in temperate climates, they offer an early start on the growing season. Crop processing equipment, including threshers and mills, can reduce losses caused by traditional techniques and save much low-productivity labor time. Very small-scale equipment of this kind could allow the small farmer to retain full crop production instead of paying 10% or more to the mill owner. Crop storage is a prime area for improvement as a significant percentage of food produced on small farms may be lost due to poor drying and storage. Low-cost, small-scale storage bins are particularly promising (see CROP DRYING AND STORAGE chapter). In many areas it is difficult to move agricultural inputs to the farm, harvested crops from the fields to storage, and surpluses from the farms to markets. Appropriate transportation technologies are thus of great importance to the farmer (see TRANSPORTATION chapter).

Many of the books in this chapter make recommendations as to the kinds of agricultural tools and equipment most needed by small farmers in developing countries. Encyclopedic listings of commercially available equipment are contained in Tools for Agriculture and two other books. These and the books documenting older small-scale equipment contain a wealth of ideas that may stimulate the imagination of readers. Rural Africa Development Project describes a method of identifying labor bottlenecks in the agricultural calendar.

A group of excellent books on the use of draft animals are reviewed. Animal-drawn equipment, carts, harnesses, and draft animal training techniques are well-covered in these comprehensive volumes.

Solar photovoltaic irrigation pumps are discussed in several entries, including information on cost and output. (Hand and foot-operated pumps for irrigation have made an impact in some countries such as Bangladesh; these pumps are covered in the WATER SUPPLY chapter. Wind-powered irrigation pumps are to be found in the ENERGY: WIND chapter.)

On North American family farms, the partner is often expected to act as a mechanic and handy-person during daily farming activities. The well-equipped farm workshop and multiple skills have continued to play a powerful role in generating farm equipment innovations. Mechanics in Agriculture is a text for vocational courses teaching the skills commonly required on these farms.

A large number of small engines are used in the South for power tillers, irrigation pumps, crop processing and other applications. The two books on small engines should be helpful references for maintenance and repair of many of these power units.

Most of the remaining entries are plans for threshers, winnowers, corn shellers and so forth, all of them hand or foot-operated, that can be produced in small workshops by local craftspeople.

Understanding the Tool Making Process

A tool maker understands the product design and creates parts, tools and dies, to be used in the manufacture. The tool maker’s advice may also influence the industrial designer – so that the idea can be made easier. The tool maker will typically work in a specialist machinist shop, and using a number of different hand tools and even often other large equipment such as lathes, milling machines, grinding machines, jig borers to make those tools and parts. Many tool makers now use computer aided design, and computer aided manufacturing and machining tools to execute their tasks. For example if you need a die to cast your new components, it is the tool maker that makes this die for you. If your die has been used for considerable time and it has become worn out, it is the tool maker who repairs it for you. Certain delicate jobs, however, require a tool maker to perform cutting, grinding, and finishing tasks by hand.

Tool making: Tool making generally means making tooling used to produce products. Common tools include metal forming rolls, lathe bits, milling cutters, and form tools. Tool making generally includes high precision, so that parts can be made perfectly many times over, or machine tools used to manufacture, hold, or test products during their production. Due to the unique nature of a tool maker’s work, it is often necessary to make custom tools or modify standard tools. Tool making is making the tools we need to produce. A simple example is the tool maker makes the tool so that you can use it to make other items, you might need a slightly different hammer for your purpose. When your hammer is broken, the tool maker will fix it. Your tool maker will also make you dies for casting.

Die making: This is a common and very important genre of tool making. Making the dies for many processes of production in molten casting, or even for casting the parts of plastic injection moulding – the tool makers job is varied and very hands on. The tool maker makes the cast so that production can be executed many times over, effortlessly and perfectly. Using the example of the hammer, the tool maker makes the cast, so that the hammer can be produced so that you can use it to do something. With large and high volume manufacturing, the tool maker is often required to make die sets that are machined with tolerances of less than one thousand of an inch.

Complete process: Tool making may and normally involves the original design of new machines and tools, to match production of a new product design. This includes original blueprints through to testing and construction of the tools that a factory will use to output a new product. When we are considering parts for large machinery and factory equipment, the tool maker must have an understanding of the assembly process. Once a machine is fully assembled, the toolmaker will test, and make sure the tool can be used as a part of the production process, to output the desired component as originally designed.

Essential. Tool makers are essential engineers understanding much more than the process of production from design, they understand how to make the things, that will be used to make that idea a reality.

Button Making Process

Textile is one of the earliest inventions of our civilization. As time passed by, fabrics got refined and many textile accessories too were invented for the comfort of using these fabrics in an effective way. As textile became a style and fashion statement from being a mere necessity, these simple accessories also got trendy. One of the good examples of such accessories is the commonly used fabric closure, the button.


Journey of Button

Buttons date back to prehistoric period when they were made from stones and bones. Gradually, they began to be made out of a variety of materials including wood, brass, pewter, gold, and silver. The buttons were first made and used in Europe. By 18th century, the button industry flourished all across Europe, and many different techniques for making buttons were developed by the artisans there. By the late 18th century, metal buttons started to be made in factories but they were a bit expensive. Although, England tried hard to stop the emigration of its die-makers, who made buttons, yet the technique spread in the other parts of the world.

By early 20th century, inexpensive buttons, made of sea shells or other natural materials in a wide range of varieties, were available and then came the plastic buttons sometime in 1930's. After World War II, almost all the buttons were made out of plastic. They could be mold cast, where plastic slugs cut from a long rod are placed in a two-part mold. The mold is then closed, and heat & pressure applied to finish the button. In yet another process of injection molding, melted plastic is forced into a mold with a button-shaped cavity. In present times, the process most commonly followed for making buttons out of plastic is that of 'die cutting from cylinder-cast polyester'

Manufacturing Process of Buttons
The basic raw materials for making buttons is polyester, a special kind of plastic, and wax. Many chemical dyes are also added to polyester to give it different colors. Chemical catalyst is also used to harden the polyester and wax. Polyester, used for making buttons, is initially in liquid form. First of all, polyester is drained from the storage tank into a stainless steel kettle. For making colored buttons, chemical dye is added. Red carbonate, carbon black and titanium are mixed for obtaining pearl like sheen similar to shell buttons, black and white colors respectively. After the dye has been mixed, the liquid polyester is poured into a metal beaker having capacity of approximately 3-gallons or 11 liters. At this stage, the chemical catalyst and liquid wax are added to the prepared mixture of polyester and the dye.

The prepared mixture is then placed into a large rotating metal cylinder made of steel and lined with chrome. The cylinder is typically 2 feet long and 4 feet in diameter. The cylinder lie on its sides on rollers which rotate the drums at about 250 rotations per minute. The polyester mixture is slowly poured into the rotating interior of the cylinder. The centrifugal force of the rotation causes the polyester solution to spread, lining the drum with an even sheet. When thicker buttons are needed, greater amount of polyester is used while less polyester is used for making thinner buttons. A 2-inch lip around the ends of the cylinder prevents the polyester solution from leaking out.◦As a result of reaction with the chemical catalyst, polyester, rotating in the cylinder, begins to harden. As the wax rises to the top of the sheet, and also sinks to the bottom, the hardening polyester is held between two layers of wax. After about 20 minutes of rotation, the polyester sheet changes from its liquid state to a crumbly solid sheet having consistency of stale cheese.

◦After the hardened sheet of polyester is made, it is cut and rolled out of the cylinder onto a wooden tube. Although, it is still delicate, wax helps in removing the sheet without much effort. Top layer of the wax is then peeled off, and the sheet is placed into a blanking machine

The blanking machine moves the polyester sheet on a conveyor belt and as the sheet passes along the belt, circular shaped cutting dies, made of steel, descend over it and punch out button-sized circles, known as blanks. Although, standard size of buttons is specified and the dies are prepared accordingly, dies with different diameters according to the requirements can also be made and loaded into the blanking machine. After the blanks are cut, they fall into a chute, and the punched out polyester sheet rolls beneath the chute. This whole process of cutting the sheets take about 2-4 minutes, depending upon the size of the buttons being made.

As the blanks are still hot, a cooling process, having hot and cold baths, follows. The blanks are placed into a nylon bag directly from the chute. The bag is placed into a tank of salt water, which is heated at 110°C, wherein the bag floats for about 15 minutes. As the water slowly cools, the polyester blanks get hardened. Then the nylon bag is transferred to a cold water tank, where the blanks reach their final state of hardness. Then the blanks are dried in a centrifugal drying machine, which spins them in a wire mesh basket.

◦The final stage of button making involves designing the buttons according to the buttons suppliers or garment companies specifications. Different cutting tools are used for making different shaped buttons such as beveled edge, or a slightly concave button. The cutting tool is placed in the cutting machine and the buttons are poured into a hopper at the top of the machine. The blanks fall into a holder where they are clamped tightly and moved toward the cutting tool. The spinning blade comes out and cuts the button and then retracts. Then the buttons moves beneath a set of drills, which make the holes in them. The design specification allows two or four holes, and also the diameter of the holes and the distance between them. After the holes are made, the buttons are sucked by vacuum out of the holder and into a box beneath the machine. Hundreds of buttons are made in a minute, though the number varies according to the size of buttons and complexity of the design.

The buttons thus created have rough or sharp edges, scratches, and tool marks and therefore need finishing process. They are Kept into hexagonal tumbling drums, that contain water, abrasive material, and a foaming agent. The drums spin for about 24 hours. The buttons bounce around in the drum until they are smooth and shiny. Lastly, the buttons are washed and dried.

Different types of Tool and Die Maker Apprentice Training Course List

Basic Industrial Math
Addition and Subtraction
Multiplication and Division
Fractions, Percents, Proportions, and Angles
Metric System
Formulas
Introduction to Algebra

Practical Measurements
Linear and Distance Measurement
Bulk Measurement
Temperature Measurement
Energy, Force, and Power
Fluid Measurement

Trades Safety: Getting Started
Working Safely with Chemicals
Fire Safety
Material Handling Safety
Electrical Safety for the Trades
Working Safely with Electricity (Video)
Jobs, Companies, and the Economy: Basic Concepts for Employees
Manufacturing Processes, Part 1
Introduction to Print Reading
Dimensioning
Tolerancing and Symbols
Sectional Views and Simplified Drafting
Reading Shop Prints

Hand and Power Tools
Common Hand Tools, Part 1
Common Hand Tools, Part 2
Precision Measuring Instruments, Part 1
Electric Drilling and Grinding Tools
Power Cutting Tools
Pneumatic Hand Tools
Plumbing and Pipefitting Tools
Electricians' Tools
Tool Grinding and Sharpening
Woodworking Hand Tools
Routers, Power Planers, and Sanders
Jacks, Hoists, and Pullers
Bench Work, Part 3
Fasteners

Basic Machining Skills
Practical Shop Math, Part 1
Practical Shop Math, Part 2
Practical Shop Measurement
Safe Shop Practices
Properties and Classifications of Metals
Using Shop Drawings, Process, and Routing Sheets, Part 1
Using Shop Drawings, Process, and Routing Sheets, Part 2
Layout
Metal Cutting and Machine Tooling, Part 1
Metal Cutting and Machine Tooling, Part 2
Metal Cutting Machinery, Part 1
Metal Cutting Machinery, Part 2
Fundamentals of Grinding
CNC Machine Tool Features and Applications
Machine Shop Safety
Precision Measuring Instruments, Part 2
Precision Measuring Instruments, Part 3
Tool and Die Making
Drilling
Metal Processing
Ferrous Metals
Nonferrous Metals
Identification of Metals
Lubrication, Part 1
Lubrication, Part 2
Applied Geometry
Practical Trigonometry
Layout
Lathes, Part 1
Lathes, Part 2
Lathes, Part 3
Lathes, Part 4
Lathes, Part 5
Milling Machines, Part 1
Milling Machines, Part 2
Milling Machines, Part 3
Basic Engine Lathe (Video)
Milling: Machine Practice
Fundamentals of Grinding
Cylindrical Grinding, Part 1
Cylindrical Grinding, Part 2
Surface Grinding, Part 1
Surface Grinding, Part 2
Nontraditional Machining Technologies
Hardening and Tempering
Tool Grinding
Geometric Dimensioning and Tolerancing
Quality Concepts: Tools and Applications
Quality Control for the Technician
CNC Technology and Programming
Toolholding Systems
Milling and Tool Sharpening (Video)
Machine Sketching
Metallurgy of Iron
Metallurgy of Nonferrous Metals
Metallurgy of Steel
Metallography
Heat Treatment
Toolmaking
Gage Making
Jigs and Fixtures
Jig and Fixture Making
Dies and Die Making
Making Forging Dies
Forging Dies
Manufacturing Processes

Best Engineering Drafting Tools

Although much of today's drafting projects are completed using software, any technical drafter should have a good understanding of the different manual tools used to complete a drafting project. Many people continue to use the manual drafting process even after mastering drafting basics. The art of technical drawing is a precise one, and the tools used to complete a project are designed to create the most accurate scale model possible in the smallest space. The following outlines the best tools you can provide yourself as a prospective drafter.

Architect's Scale

The architect's scale is a three-sided ruler constructed either of plastic or aluminum. A high-quality architect's scale will offer you a larger number of fractional scales. Different fractional scales will allow you to create a larger assortment of technical drawings. Like any ruler, the architect's scale offers flat sides for straight drawing ease. Purchase an architectural scale that has been constructed of hard plastic, as the corners on aluminum models can bend if the scale gets dropped. Because of the flow of manual use, many drafters find it easier to construct drawings using an architectural scale and pencil rather than CAD, or computer-aided design, software.
Bow Compass
Bow compasses aid the drafter in creating curved lines and circles within their designs. The bow compass can be vital, as it is the only tool that can accurately draw curved lines to scale. The bow compass will have a point that stays in the middle of the circle, and another end to hold a pencil or other lead source. You can create a perfect circle with a bow compass by holding the compass' point in one position and rotating the pencil end around that fixed center. A ruler placed through both sides of the bow compass allows you to control your circle's size.
Divider
Dividers look much like bow compasses, but instead of a pencil holder or lead source, the divider has two metal points and is used to transfer measurements to a technical drawing. When applied with pressure to drafting paper, dividers can leave marks that are clearly visible upon closer inspection. A high-quality divider can be locked into place to ensure the consistency of your measurement.

Protractor
Protractors are semicircle-shaped pieces of clear plastic that help a drafter create whatever angle they need for a design. Find the center point of your protractor. It will be located on the long bottom line, usually surrounded by a tiny circle. Place that center point on your design exactly where you want your line to start. Because drafting designs are drawn to scale, the angle of the corner in real life is the same angle you will use on your protractor. Find the degree value you need on the outside of your protractor, and then make a small mark on your drawing at that location. You can then draw the line at the proper angle by lining up the flat edge of your architectural scale with both the line's beginning and your angle marking. Be careful to make sure the line you draw is still to scale.

Triangle
A triangle will help you draw a parallel or perpendicular line through another line in your drafting project. To draw a perpendicular line, simply line up the short end of your clear plastic triangle on the line you will be drawing through with the point where the lines intersect somewhere in the middle of your triangle. Place your architectural scale against the hypotenuse of your triangle, and slowly move the triangle down along the scale until the point of intersection reaches the long side of the plastic triangle. Drag your pencil along the triangle's long side to create a perfectly perpendicular intersection.

To draw a line parallel to another in your drafting project, line the long edge of the triangle up with the line you want a parallel line for, and then line your scale against the short edge of your triangle. The scale should be lined up with the line so that the line rests at the 'zero' position, or the spot where you would begin any measurement. Move your triangle down the scale, without changing its angle, and stop when the long edge of the triangle has reached the proper distance between the lines. Drag your pencil along the long edge of your triangle to complete a perfectly parallel line.