Woodworking router bits ( milling cutter ) is a rotary cutter with one or more cutting edges, which is mainly used for woodworking milling processing. When the cutter body rotates, the machined object does not rotate, and the cutter teeth intermittently cut off the redundant wood in turn, similar to metal cutting milling cutter.
Structure of woodworking milling cutter
Chip evacuation groove: the groove of the milling head is a deep spiral groove running along with the cutter, while the sharp blade along the edge of the groove is called the blade. The cutting edge cuts the material, and the chip of the material pushes the chip discharge slot through the rotating drill bit. Each chip chute has almost always had a blade, but some cutters have two blades per chip chute. Generally, the chip chute and blade can be used interchangeably. Milling cutters may have one to more blades, and two, three, and four are the most common. Usually, the more teeth the blade has, it can remove the material faster. Therefore, the 4-tooth cutter can cut materials at twice the speed of the 2-tooth cutter.
Helix angle: the groove of the milling cutter is almost always spiral. If the chip chute is straight, the entire blade will immediately impact the material, causing vibration, reducing accuracy and surface quality. The chip discharge slot can be set at a certain angle to make the blade gradually enter the material and reduce the vibration. Usually, the finishing tool has a higher spiral angle to get better machining.
Router bits handle: a handle is a cylindrical (non-groove) part of a tool that is used to secure and position it in the tool holder. The handle can be completely circular and held by friction or may have a welding plane, where the set screw is also called a headless screw that contacts without tool sliding to increase torque. The diameter may be different from the diameter of the cutting part of the tool, so it can be maintained by a standard tool clamp.
What are the types of woodworking router bits?
According to processing purposes, wood milling cutter can be further divided into:
Straight knife: slotting
Bottom cleaning knife: slotting and bottom cleaning
Trimming knife: straighten the edge
Fillet cutter: rounding edge
End milling cutter: machining groove and step surface
Saw blade milling cutter: processing deep groove and cutting workpiece
Minzai knife: trimming round edge
Round bottom knife: round groove
90 ° V-knife: open V-groove and straight plate folding
45 ° Bevel knife: 45 ° hypotenuse
Horse nose thread knife: repair 60 ° Or 30 ° hypotenuse
Two arc nail clipper: drawer handle
Keyhole knife: open the frame hole and hang it on the nail
T-knife: cutting side groove or milling T-groove
Dovetail knife: board joint.
Square tooth tenon cutter: floor splicing
Fillet tenon cutter: door panel tenon
Parameter description of woodworking router bits
Although there are many types of router bits, it is important to understand the chip formation for using them. When the router bits rotates, the material to be cut is fed into it, and each tooth of the cutter cuts off a small piece of material. The size of the piece depends on several variables:
Surface cutting speed (VC)
This is the speed at which each blade passes through the material as the tool rotates. This should not be confused with the feed rate. This value is also known as tangential velocity.
Spindle speed (S)
This is the tool speed, measured in revolutions per minute (RPM). The typical value is hundreds of RPM, up to tens of thousands of RPM.
Tool diameter (D):
The diameter of the cylindrical part of the tool.
Feed per tooth (Fz):
This is the distance the material is fed into the tool as each tooth rotates. This value is the size of the deepest cut of the cutter teeth.
Feed rate (F):
This is the rate at which the material is fed into the tool.
This is the depth of the tool under the surface of the material to be cut. This will be the height of chip production. Generally, the cutting depth will be less than or equal to the diameter of the cutting tool.
Number of teeth (z):
That is the number of milling cutter teeth.
Calculation formula of woodworking router bits
Usually, we need to know three parameters: spindle speed (S), feed rate (F) and cutting depth to decide how to select cutting materials.
From the formula of spindle speed s, it can be seen that larger tools need lower spindle speed, while smaller tools may run at high speed.
The formula of feed rate f shows that increasing S or z can provide higher feed rate. So you can choose the tool with the highest number of blades, which can still handle the cutting load.
What are the processing methods of woodworking router bits?
There are two processing methods of woodworking router bits: forward milling and reverse milling. Router bits can cut in two directions, sometimes called reverse or up, forward or down.
Reverse milling: the cutting thickness starts from zero and increases to the maximum. At the beginning of cutting, the cutter does not cut, but slides over the material surface until the cutter teeth suddenly bite and start cutting. This will deform the material (point a in the figure) and blunt the tool, leaving a bad surface on the material
Forward milling: each blade joins the material at a certain position, and the cutting width decreases from the maximum to zero. The chip is set behind the cutter, which makes it easier to remove the chip. The blade does not rub against the material, so the tool life may be longer. However, climbing can impose a large load on the machine, but it is not recommended for older milling machines or machines.
How to choose woodworking router bits?
Choose the right woodworking tools, pay attention to a cost-effective. Milling cutters on the market can be divided into three grades: ordinary, high-quality and high-grade.
Some of the ordinary milling cutters are packed very ordinary. You can see that they are ordinary. There is another kind of ordinary milling cutter with paint and a transparent shell. This kind of milling cutter looks like a boutique. Its essence is ordinary. You should be careful when choosing it. Some of the high-quality milling cutters are packed simply, while others are packed fancy. The sharpness of the blade is the main factor for this kind of cutters. Generally speaking, the brighter the blade is, the finer the workmanship is. High-grade milling cutter is reliable in quality but expensive.
Generally speaking, ordinary milling cutter is used for low-density and low hardness plates. Plates with nails have a high loss of milling cutter. Ordinary milling cutter is used for few plates. Good milling cutter is used for high-density and high hardness plates. Good milling cutter is used for acrylic plate and artificial stone.