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6   Phone: 516-328-3970 www.technocnc.com Technical Section Router  to  invest  in,  there  are  several  important  aspects to  consider.  The  end  result  of  CNC  Router  design  and construction should be greater than the sum of its parts. The quality of a CNC Router’s components, in addition to the history and reputation of the company, should be weighed heavily during the buying process. This  technical  section  will  cover  vital  aspects  to  the buying process, such as: spindle options, tooling basics and maintenance, fixturing requirements, CNC accessories and software; items which, when looking to purchase a CNC Router, should be considered without exception. However, the fi rst topic to be considered is the router itself. The CNC Router market runs the gamut from hobbyist machines at $5000, up to huge CNC machining systems that cost in excess of $200,000. The idea is to fi nd the CNC Router with the right price to performance ratio within your budget. Size and space requirements should be decided upon before other more complex CNC features. Allotted shop space in relation to a router’s work envelope can determine whethera14”x19”tabletopmodelora59”x120”CNCsystem with a moving gantry are the right machine specifications to research. After  deciding  on  a  machine’s  footprint  (e.g.,  109”  x 149” x 60”), the element that greatly determines the quality, durability and overall performance of a CNC Router is found in its drive components. Basically, what method is used to move the machine’s axes. Techno’s CNC Routers utilize THK  rails  and  ball  screw  drives,  which  provide  smooth play-free  motion,  require  minimal  maintenance,  provide excellent accuracy and long life. The placement of the ball screw is in the center of the axis of travel, which eliminates the possibility of racking (i.e., when the system twists due to misalignment). This also ensures that the Techno machine does not need to be realigned ever, causing no wear on the  drive  or  carriage  system.  Eliminating  the  downtime spent repairing damage from racking, results in increased productivity and profits. Some CNC Routers use other drive systems, such as the  rack-and-pinion  gear  drive.  The  racks  are  typically installed on the outside of the machine, thus exposed to the elements. As the machine cuts, debris collects on the rack. These foreign materials get ground into the racks and gears, causing more friction in the drive system which, in turn, causes wear and makes the machine less accurate and unstable. In a rack-and-pinion system, there are typically two drive motors required to run the one axis (one on the right side and one on the left side of the machine). The two motors must stay completely in sync with one another. When these motors get out of sync, racking occurs. Racking deforms the gears within the system, wearing down the components, and the unit itself can be jolted out of square. The choice between what drive motors to use fi rst comes down to either servo or stepper motors. Servos are typically the more expensive motor, but certain Micro-Stepper motor options bring parity to the purchase price. The big difference between the two motors is in how they run. Steppers, as the name implies, have a set number of steps per revolution. Movement is measured assuming that each commanded step has been completed. Most steppers are run in what is called an open-loop configuration. This means that the location of an axis is not verifi ed on an ongoing basis. The motor is commanded to move a certain distance and it is assumed the move is successful without verifi cation. This can cause problems when excessive vibration or resonance from the motor/machine construction can cause the stepper motor to lose steps or even stall. CNC Router Components