When not all layers of your 3D print are printed correctly, this is probably due to under extrusion. Under extrusion is a complex problem that can cause missing layers or layers that are not completely printed, leading to holes in the model. Unfortunately, we cannot point out one single culprit. Under extrusion can have various causes, which makes it hard to determine the actual problem. It mostly has to do with using the right extrusion width.
Unfeasible extrusion width
When we’re talking about extrusion width, we mean the width of the printing layer that the printer extrudes. How wide or narrow this layer can be, depends on the used nozzle size. The printer software has default values for how broad a layer can be for a certain nozzle size (100% is the minimum extrusion width for every nozzle and 120% the maximum). When you enter a too thin layer value or when you use the wrong nozzle, the layer cannot be converted to a printing layer and it will therefore not be printed. This results in missing layers in your model. Check which extrusion width should be used and whether you use the right nozzle for this width. When you cannot obtain the desired width with any nozzle, the model will have to be adjusted in the CAD software. You can also manually adjust the extrusion values in the printer software, but the possibilities are limited because it needs to be technically feasible.
When under extrusion occurs, you would expect the solution to lie in pushing more filament through the nozzle and thus adjusting the pressure. This is possible, but only to a certain extend and with the right temperature. When the pressure is too high, the chance of a clogged nozzle is very big. Which in turn causes under extrusion to occur again, because the filament isn’t printed correctly anymore.
Under extrusion is an adhesion issue, that could be caused by an unfeasible extrusion width. The dddrop printers have changeable nozzles, which allows for a big range of extrusion widths that can be printed. Furthermore, dddrop delivers the right basic settings for each material which helps to achieve the best result possible.