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Mohammed Samaneh
Mohammed Masoud
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   Simple introduction A CNC router is a router whose tool paths can be controlled via computer numerical control. It is a computer-controlled machine for cutting various hard materials, such as wood, composites, aluminum, steel, plastics, and foams. It is one of many kinds of tools that have CNC variants. A CNC router is very similar in concept to a CNC milling machine.   CNC routers come in many configurations, from small home-style "desktop" CNC routers to large "gantry" CNC routers used in boat-making facilities. Although there are many configurations, most CNC routers have a few specific parts: a dedicated CNC controller, one or more spindle motors, AC inverters, and a table. CNC routers are generally available in 3-axis and 5-axis CNC formats.   The CNC router is run by a computer. Coordinates are uploaded into the machine controller from a separate program. CNC router owners often have two software applicationsone program to make designs (CAD) and another to translate those designs into a program of instructions for the machine (CAM). As with CNC milling machines, CNC routers can be controlled directly by manual programming, but CAD/CAM opens up wider possibilities for contouring, speeding up the programming process and in some cases creating programs whose manual programming would be, if not truly impossible, certainly commercially impractical. CNC routers can be very useful when carrying out identical, repetitive jobs. A CNC router typically produces consistent and high-quality work and improves factory productivity. A CNC router can reduce waste, frequency of errors, and the time the finished product takes to get to market.   A CNC router gives more flexibility to the manufacturing process. It can be used in the production of many different items, such as door carvings, interior and exterior decorations, wood panels, sign boards, wooden frames, moldings, musical instruments, furniture, and so on. In addition, the CNC router makes thermo-forming of plastics easier by automating the trimming process. CNC routers help ensure part repeatability and sufficient factory output.     Palestinian view We chose this project to carry out because of the following reasons:   The high cost of importing CNC machines from outside of Palestine.     Lack of skilled operators to deal with CNC machines in addition to the high cost of training technicians outside Palestine.   Unavailability of agents authorized to carry out maintenance and supply of spare parts for maintenance of CNC machines as well as the high cost of recruiting foreign technicians to do the necessary maintenance work.   Customs and security restrictions imposed by the Israeli authorities in the face of import of CNC machines, spare parts and other industries related to the CNC field.   Lack of development of the field of CNC in Palestine constitutes an obstacle to industrial progress in Palestine. For this reason, there isnt a possibility to manufacture mechanical parts and production lines on a high level of quality.   Log of CNC machines in the timber industry and home furnishings and other would raise the quality of national products and make a possibility to export it to the outside.       Starting point We start the project by choosing a studied mechanical model. Then we calculate maximum torque the machine should maintain. Then we chose the suitable type of motors based on some important points like driving circuit, simplicity, price and other things. We designed the printed circuit board and built it. After preparing all project parts we combined the whole parts producing our simple model of CNC routing machine.     General idea about our machine   Three dimensions CNC Routing machine with 3axis. It will have mechanical structure have the capability to move in the three axis which are X, Y, and Z axis. Driving the spindle in these axis will cause the working piece to be routed. There will be an electronics attached to the structure to drive it. These electronics will handle the electrical signals came from the numerical controller (computer) to drive the structure.   This structure will have the ability to move in the three direction X,Y and Z axis. The element that will be responsible of routing the wooden piece is the spindle motor. This motor will be installed on the Z-axis of the machine. Z-axis movement will done by a power screw attached to a stepper motor. That power screw will convert the rotational movement of the stepper motor into linear movement toward the (+) Z or (-) Z-axis depending on the direction of stepper motor rotation. The Z-axis will be installed on the Y-axis of the machine on this case, the hole structure of the Z-axis will move along the Y-axis. The Z-axis structure will be connected to a power screw which will be attached to another stepper motor.      At the same way, the hall structure of the Y-axis will move along the X-axis. So we installed a power screw and attached a third stepper motor to it. At the end, the mechanical structure is ready to be moved in the three axis. The movement of the structure will be in response to the rotational movement of the stepper motors and screws attached to it. The displacement of each axis depends on the lead value of the screw we used. Lead value is simply the amount of axial travel that the nut will experience during one single rotation of the screw shaft.   About driving circuit The drive circuit will contain all the components shown previously. One of the main functions of this drive circuit is to drive the stepper motors attached to each axis. Drive circuit will take movement instruction from the numerical controller (computer) through the parallel port. These instructions are two signals, one for number of steps and the other for direction of rotation.  Signals coming from the parallel port will be optically isolated from the drive circuit. Now we get to the block diagram shows the relations between the components in a single axis driving module.  This module will be repeated for the other two axis driving modules. Another function that the drive circuit should do is to pass feedback signals coming from the limit switches and the E-Stop button to the computer through the parallel port. Also feedback signals will be optically isolated to protect the computer hard ware. This leads us to design the drive circuit to meet the requirement of driving the machine.     Protection partsWe also didnt forget to protect user in our machine, so we used limit switches, emergency push button and isolating technique in order to isolate control circuits from power circuits.  Results: We satisfied to run the machine but using frequency generator instead of MACH3 program. This was because of the distortion on the computer signal from electronics. Finally I have to say it was very good experience to do so and I hope from electronics traders to import good electronics instead of faulty.