Numerical milling machine - rigidity and play control
In order to be able to consciously choose the right CNC milling machine model for the intended application, it is worth learning a little more about the construction details and key parameters of this type of equipment. Very important for the quality of obtained machining results is the execution of the supporting structure and drive system, allowing for feed in all three main axes (machine tools with a greater number of degrees of freedom are usually not found among amateur and semi-professional solutions). The structure should be rigid and free from unnecessary backlash - any inaccuracies in the machine will be reproduced in the workpiece, both as deviations from the set dimensions (e.g. too large diameters of holes) and as "jagging", waving on flat surfaces, etc. visible to the naked eye. Unfortunately, in case of lower quality machines, bringing them to the desired level of accuracy is in many cases a complicated and often expensive task. Therefore, it is necessary to pay close attention to the type of structural profiles, their dimensions and the type of guiding grooves - sometimes such seemingly insignificant details may affect the effects of the work.
Spindle power and type
Another very important element in the construction of a numerical machine is the spindle. It is an electric drive with a solid, bearing construction, used for direct transmission of rotations to the tool - usually a cutter or a drill. The power of the spindle depends on speed and torque - some types of materials (e.g. aluminium) should be processed at high speeds, but with relatively low torque. For some steel alloys, on the other hand, it is recommended to significantly reduce the number of revolutions per minute, but high torque is important - this is why CNC woodworking machines use different spindles than robust, expensive CNC metal milling machines. While small spindles can be used for delicate, easily machinable materials (e.g. plastics or soft wood), solid drives with a power of more than one kilowatt, equipped with powerful brushless motors, controlled by suitable inverters, become a necessity for metalworking. By the way, it is worth adding that the demand for torque increases not only with the hardness of the raw material, but also with the diameter of the tool - it is difficult to imagine grooving the material with a 16 mm cutter with a spindle that is adapted to tools with a diameter not exceeding a few millimetres.
WorkBee v2.1 CNC milling machine - a solid base for building your own CNC machine
The problem, which sooner or later will be encountered by a person interested in building his own CNC milling machine, is to make a suitably rigid support structure with small slack and high positioning accuracy. The creators of the WorkBee v2.1 project are well aware of this fact, which is why they introduced a set for assembling the base of a large milling machine with a working area of 800 x 770 mm. The whole is based on high quality V-Slot and C-Beam aluminium profiles and the bogie drive is provided by high quality ACME screws. The kit does not include the motors, spindle and controller themselves - the choice is up to you. Fortunately, it is not a problem today - we offer various types of stepper motor controllers as well as the drives themselves, available in the most popular NEMA23 standard. It is worth knowing that many amateur CNC milling machines constructors base their projects on controllers based on Arduino platform - there is even free software available on the network, which greatly facilitates the integration of the whole control system of CNC milling machine.