All of the motion axes are coupled to a single sheet metal part, reducing the need for factory calibration and ensuring that your Robox® is perfect for printing straight off the production line. The use of injection moulded parts combined with sheet metal components produces a very rigid structure, while allowing for a stylish consumer product.
By using a ‘Bowden tube’ extruder, we are able to keep the weight of the printing head to a minimum, allowing for much faster extrusion and travel speeds without affecting print quality.
Large High Torque Stepper Motors with High Resolution Axes
We have over-specified the stepper motors for all the motion axes, meaning Robox® should be able to cope with all future head developments without a hitch. We have used 2mm pitch belt drives for X and Y axes and our own custom machined 0.5mm pitch Z axis screw. All of the motors are custom designed for the printer. This gives us the highest theoretical accuracy on the market, and allows us to achieve super-fine layer height.
Separate Build Chamber and Electronics Enclosure
Due to the heated build platform, we can maintain approximately 50°C ambient temperature in the build chamber. This stable environment helps to maintain part accuracy and print quality by preventing uneven cooling. The problem with this feature is that this ambient temperature can be too hot for the motors and electronics which control the printer. These are all therefore outside the build chamber and actively cooled by outside airflow to keep everything running smoothly.
Automatic Build Platform Levelling
One of the major problems with almost all available 3D printers is that the bed must be manually levelled to ensure the first layer adheres correctly. This is be a fiddly process which has to be regularly repeated – a source of frustration for other 3D printer owners! Well, we’ve solved that. Robox® uses a proprietary bed probing mechanism which can measures the location of the bed before every print. As both Z motors are driven independently they can be adjusted to ensure the X axis is always parallel to the print bed.
Extruder Construction and Feedback Loop
The Robox® extruder contains the world’s first dual-pinch-wheel extrusion system. This allows for very consistent and reliable extruder operation with excellent resolution and control. The filament is fed to the head by two indexed contra-rotating feed wheels which are powered by a worm & wheel gearbox. This arrangement virtually eliminates the possibility of ‘stripping’ your filament, causing a loss of extrusion and poor print quality.
Pause and Resume!
The filament extruder incorporates a closed-loop feedback system which monitors the motion of filament as it enters the extruder, giving it the ability to instantly recognise extrusion issues. The software can pause the print if any error is found, allowing the user or firmware to rectify the problem without ruining the entire print. A long awaited feature on 3D printers is ‘resume’ – the user can restart the print and it will continue from where it left off. Another first for Robox®!
Nozzle Valve System
Another problem typical of 3D printers is ‘ooze’ -the stringing and over extrusion at the end of a section of printing. This happens due to the low viscosity of molten plastic. In most printers, this is solved by what is known as a ‘retract’, where the filament is rapidly reversed in conjunction with a very small melt chamber, however this is not always effective. Robox® overcomes this problem through the use of a needle-valve system which completely closes the nozzles at the point of extrusion, removing all stringing and ‘blobs’ from the part – resulting in an amazing surface finish. Because viscosity can be managed by the needle valves Robox is able to use a much wider range of materials than any other 3D printer.