What is CNC wood router:
A CNC wood router is a CNC router tool that creates objects from wood. CNC stands for computer numerical control. The CNC works on the Cartesian coordinate system (X, Y, Z) for 3D motion control. Parts of a project can be designed in the computer with a CAD/CAM program, and then cut automatically using a router or other cutters to produce a finished part.
The CNC router is ideal for hobbies, engineering prototyping, product development, art, and production work.
A wood router is controlled by CAM and CAD applications such as Artcam, Mastercam, Bobcad, and AlphaCam, which are specifically designed for use with wood routers.
Wood routers are frequently used to machine other soft materials such as plastics.
CNC Woodworking Projects:
Few types of CNC woodworking projects:
Components of CNC wood router:
1. Controller.
The controller is the brain of the CNC machine. The term controller usually refers not only to the computer but also to all the electronic and electrical devices that give motion to the machine.
There are two types of controllers available on machines today.
2. Work Table
Today are available many types of tables and these vary depending on the type of work being done and the work holding methods that are being used.
This is the most basic table offered with a CNC router. It consists of a flat surface made of laminate, aluminium or MDF. To hold down parts onto these tables, glue, double sided tape, clamps or vacuum pods connected to a small rotary vane pump are used.
T-slot tables are a by-product of the metal working industry. The only difference is that for the wood working machine, they are usually made of aluminium extrusion. These tables permit the use of inexpensive bolt-on clamps to hold down parts.
Otherwise known as nested tables, this method is used when machining parts out of full sheets of materials. Little or no access is afforded to the edge of the material but vertical accuracy is very good. Machining glued-up solid wood panels works well when the panel is flat. Fixturing is often needed when machining small parts, rough or warped solid wood parts.
3. Motions.
Motion is defined as a continuous change in the position of a body (the cutting tool) relative to a reference point (the part), as measured by an observer (the operator) in a particular frame of reference. A frame of reference is the perspective from which space is observed.
3-axis machines move in a Cartesian manner along x, y and z.
A fourth axis often takes the form of a rotating device for the part being cut, similar to a lathe or an indexing head along the spindle that permits the controlled rotation of an aggregate tool.
5-axis machines have a much greater range of motion and can move in a manner similar to the human hand. These machines often have a deep z stroke to be able to work in a large three dimensional area.
There are 6 possible axes of motion, 3 linear and 3 rotational, one of which is considered to be the cutter spinning in the spindle. The CNC machine must calculate the direction, speed and acceleration on each of the axes in order to cause the proper movement to be made. This is done with the help of complex mathematical formulas called algorithms.
4. Drive System
The drives are the devices that cause the machine to move. Three different drive motors have been used to power CNC routers:
5. Spindle
Essentially there are two different types of spindles in use today, the belt driven, stand-alone spindle and the high frequency motor spindle.
6. Tool Changers
Manual tool change is done with the spindle turned off. The nut on the collet is loosened and the bit is changed. In some cases the tool change is commanded by the program which resumes once the change is done. Most often though, a separate program needs to be run for each tool change.
Some machines simply resort to multiple heads in order to accommodate different tools. Some machines, also known as “workcenters” have multiple heads mounted on one axis that are activated pneumatically by the program. A new tool can be lowered in seconds and start cutting much faster than initiating a tool change. The consequence of having all these separate moving parts can be lower accuracy.
There are many variations of tool holders. The two most prominent kinds in the CNC router market are ISO-30 and HSK63F. Although the HSK63F is more stable and can handle a larger tool, it is more costly and more prone to dust contamination than the ISO-30 tool changer. The cutting tools are set into the tool holder by various means. The most common is a tapered collet that is tightened by a nut. Other methods use hydraulic pressure or heat shrinking. Hydraulic locking tool holders and heat shrink tool holders are more expensive and require special equipment but they hold the tool much better which results in a more balanced tool, less vibration and a better cut finish.
Automatic tool changers are actually a specially designed spindle. This spindle uses a drawbar to pull a tapered tool holder into a tapered receptacle at the bottom of the spindle. This drawbar has several fingers that grip a knob screwed into the end of the tool holder. When the drawbar retracts, it pulls the tool holder tightly into the spindle taper.An automatic tool holder can be manually changed by pressing a button that releases the tool holder. A new tool holder can then be inserted by hand into the spindle. The simplest form of automatic tool changer is called the bar style tool changer. It is usually located at one end of the machine and consists of a series of receptacles. To change tools, the head moves to an empty receptacle and deposits the current tool. It then moves to the location of the next tool and retrieves it.
7. Tooling
Tooling, surprisingly enough, is often the least understood aspect of CNC equipment. Given that it is the one element that will most affect the quality of cut and the cutting speed, operators should spend more time exploring this subject.
Cutting tools usually come in three different materials;
8. Linear drive system
Each axis employs a linear drive system that moves the spindles in that axis. The CNC linear drive system includes a motor, a linear bearing system, and some sort of lead screw assembly.
9. Gantry
The moving table and the moving gantry designs are the most common in industry today.
The moving table machine is more popular than the moving gantry machine, not because it is inherently more stable but because of a control system limitation. A moving table machine has a single lead screw moving the head back and forth on the gantry and a single screw moving the table front to back.
A moving gantry machine has the gantry mounted to a rail located on either side of the table. One lead screw moves the head back and forth on the gantry, but two lead screws are required to move the gantry. As a result, the moving gantry machine requires one extra servo motor and drive making it more expensive.
10. Software
Software is at the heart of any NC machine. Even the most advanced piece of machinery cannot perform to its full potential without the proper software to make it happen. It is also the area that will require the highest skill set on the path toward CNC success. There are many levels of software needed to run a CNC router: from the technical drawings to the sales requirements and scheduling, to the actual NC code that makes the axes move. All have a specific role to play in the overall solution.
The acronym for Computer Aided Design (CAD) originally meant Computer Aided Drafting because of its use as a replacement for traditional drafting. CAD is used to design, develop and optimize products which include goods used by end consumers or intermediate goods used in other products.
Computer Aided Manufacturing (CAM) takes the CAD drawings and helps translate them into manufactured parts by adding tool sequences, machining parameters, cutting speeds, etc. CAM refers to a wide range of computer-based software tools that assist engineers, tool and die makers and CNC machinists in the manufacture or prototyping of product components.
Parametric design software has often been associated with very specialized industries but it is becoming more and more widespread.
Nesting or optimizing refers to the process of efficiently manufacturing parts from sheet goods to minimize waste. Although most nesting is done through the CAM software, there still exist stand alone nesting programs. Some will import part descriptions from other CAD or CAM software and others will also permit the user to import cut sizes directly from sales or spreadsheet software.
A post processor is a program that translates the centreline data it receives from the CAM software into the NC code that the machine will use to machine the part. There must be a post processor for each CAM software program and for each CNC machine. Even similar machines of the same make and model require subtle tool shift data that is unique to each machine
G-Code is the language that the CNC understands in order to move its axes and perform operations. Also known as RS-274D, it is the standard for numerically controlled machines and was developed by the Electronic Industry Association in the early 1960’s.