Operate Routers
Topic 9 – Operate Routers
Routers
The router comes in a variety of styles (see figure 69 below). While the basic is operation remains the same, their application varies. They are all at their essence a motor attached to a chuck which holds a bit. The size of routers varies, and is usually indicated by its motors HP. Routers are available from ¼ HP to over 3 HP and can produce speeds of up to 35,000 RPM. Many routers come with variable speed.
The size of the chuck (known as the collet) can often be changed to fit different sized bits (most commonly ¼” and ½”). The size of the collet must correspond to the size of the bits’ arbor. The depth of the bit can be adjusted at the arbor to a small degree. Many routers also have an adjustable base which is used to adjust the depth of cut.
Router Bits
Router bits come in many different profiles and sizes. Generally, routers are used for trimming and shaping an edge of material. These bits contain a pilot bearing which guides the bit to produce a consistent profile (see figure 75 right). The bit is held by the arbor in the collet while the cutter defines the profile that will be cut. The cutter typically contains deep flutes which are used to collect and expel saw dust as it enters and exits the material.
Some router bits do not have a pilot bearing. These are used for making cuts and profiles within a piece of stock such as roman ogee, dados, and dovetails.
***Considering the variety of sizes router bits come in, what do you think the relationship between the bit and cutting speed is?
Maintaining and Operating the Router
When changing the bit, always check and make sure the power source is removed. The collet is loosened with two specialty wrenches. If the bit becomes stuck in the collet, tap the side to release the jaws and free the bit. When placing the bit in the collet, ensure that it is tight and secure with no movement.
When operating the router, the order and direction of cutting needs to follow specific rules. Do test cuts on a scrap piece when testing for depth of cut. When operating by hand, the router is fed along the material from left to right (when routering inside holes or slots, the operation is completed clockwise). Running the router with the rotation of the blade will result in chattering and jumping of the router. Because of the aggressive cut that routers produce, it is important to be aware of the tear out that can occur. When routering all four edges of a piece of wood, rout the end grain first, then the edges with the grain (see figure 7 right). Alternatively, one may also cut the edges in the following order (in reference to figure 7): 1,4,2, and 3.
Figure 7: the order in which edges of lumber should be routered
For smaller pieces, it is recommended that a router table be used, which is simply a table that is designed to hold the router underneath with the bit protruding through the top. The pilot bearing works the same as with hand operation, or a fence can also be used. When using a router table, the cutting action is done in reverse direction (the piece runs from right to left).
Review Questions
- What determines the size of bit that can be used in a router?
- What are the two most common arbor sizes on router bits?
- Describe the function of a flute on a router bit.
- What direction do you feed a handheld router when routing the edge of a board?
- What primary factor should determine the RPM of the router?
- Other than the size of the bit, what other factor may influence cutting speed?
- What is the correct order for routering all four edges of a piece of stock?
- When routering the edges of hole inside a stool top, what direction (clockwise or counter clockwise) should the material travel when using a router table?
Topic 10 – Identify the Compressed Air (Pneumatic) System
The Air Compressor
While cordless tools are quickly taking over the construction trades, pneumatic tools still play a vital role in certain tasks. The source of compressed air, the air compressor, it the motor that drives these tools. Understanding the maintenance and operation of the air compressor is key knowledge a carpenter should possess. The air compressor (pictured right) is equipped with parts that moderate its operation to ensure it is safe for use. It possesses an automatic shutoff that prevents the tanks from being overfilled. It is also equipped with a safety relief valve which releases air past a certain pressure.
There is two pressure gauges situated on the air compressor. One indicates the pressure inside the tank. Typically, the motor will disengage when this reaches 120-130 PSI. The other pressure gauge indicates the pressure that is going to the line and tool. This gauge is equipped with a dial which allows the user to adjust the air pressure going to the tool.
Maintaining the Air Compressor
Typically, the air we breathe contains anywhere from 46-75% relative humidity (water vapour). When air is compressed, the water vapour has a tendency to condense inside the air compression chamber. As a result, liquid water builds up in the tank and, over time, can cause the tank to rust. To remediate this, the air compressor is equipped with a drain cock which allows the tank to be emptied of both compressed air and liquid water. This should be done at the end of each day when the air compressor is put away for storage (both short and long term).
Some other maintenance considerations:
Pneumatic Fastening Tools
There are a variety of fastening tools available for purchase which include:
When using pneumatic fastening tools, it is important to check that the air compressor is supplying the correct pressure to the tool. This can be adjusted and monitored at the regulator valve. If the required or recommended pressure is unknown, it is good practice to start at a low pressure and work up to an acceptable operation.
Operating Pneumatic Tools
When connecting a pneumatic fastener to the supply line, always point the tool away from people and animals as a misfire can occur when it is connected. Ensure that all parts of the tool are secure and tightened prior to connecting.
To ensure proper operation and maintenance, check the supply line for debris or moisture prior to connection. Always use the proper fasteners the tool is designed for, and oil the tool regularly (two or three drops into the supply coupler with each use).
If the fastening tool experiences a jam, disconnect the tool before servicing. Some tools have a quick release clamp to break jams free. Always follow the manufacturers directions when maintaining tools.
Review Questions
- What is the function of the following in an air compressor?
- Drain cock
- Safety relief valve
- Pressure switch
- Regulator valve
- What maintenance must be done at the end of each day that the compressor is used? Why?
- List three safety precautions that should be observed when using compressed air.
- What is the purpose of the two-step triggering process?
- What must be done before clearing a jam in a pneumatic tool?
- What should be done if the required pressure is not known for a pneumatic tool?