I have a problem with the grid infill on my BCN3D+ Dual Paste extruder: when I print a structure the lines of the infill are not evenly printed, every two lines the gap between the lines is higher (see the photo) while in the Simplify printing preview (preview image) the space between the infill lines is the same all the time. Do someone know if it can be a problem of the printer or a Simplify command?
It looks like a case of one axis affecting the other. This is a subset of cases where things are not rigid enough. Basically the movement direction in X is causing an offset in the Y, or whatever you want to call the axes. It is present in small amounts in all screw-driven setups where the screw essentially acts as a wedge, and can be in others for various other reasons. The solution is to tighten up your linear bearings/slides so that there is less transverse play.
There is also a chance that you are trying to print beyond the resolution of your printer, in which case it is "rounding" to the nearest within its capabilities, but that seems less likely.