X,Y and Z axis 150mm calibration prints

thingiverse

Two calibrators for steps per mm calibration. They are this big (150mm) so that the calibration error resulting from wrong steps per mm is more measurable and errors stemming from other things, like wrong bed levelling or over/underextrusion are less pronounced, making the calibration more accurate. It is 150mm instead of full bed size (in common Prusa I3 clones and other printers with 220mm each way working area) to avoid hitting things like bed glass clamps and other accessories one might stick onto his printer especially if the calibration is way off, and also because this is about and slightly below the usual no-brand caliper max size. The square is for X and Y calibration: the outside edges are 150mm and internal edges are 140mm in length, and I recommend measuring it while still stuck to bed to avoid bending, as well as measuring each edge from corner to corner to avoid having the calipers slightly at an angle. New steps per mm = old steps per mm * 150mm/measured length. The tower's flat top is 150mm from the bottom side, it can be measured after removal. This test is designed as a compromise between accuracy and filament/time usage (uses about 3 times the filament a 20mm cube does, but the accuracy is better). I highly recommend doing it on a really well levelled bed and after setting extruder steps/mm by marking off a distance from the hole on the filament, moving the extruder from the menu less than tthat distance and then measuring again, thus knowing the ideal and real distance it moved and calculating it the same way. The XY square should be printed at 100% fill rate but can be made lower, this thickness is just so that it is easily measured, and the Z tower can be 15%, and it can also be reused as a stand for something like a small quadcopter or a starship model later on, and I might make a version with screw holes in the top surface. The legs are there primarily so that it doesn't unstick but still uses less material than a raft with similar effect. By the way, if your bed suddenly doesn't seem to be easily levellable (a corner or the center is either a lot too high or too low despite a lot of screw turning) and the Y axis moves less comfortably, check the bed and the frame it's attached to for being bent. It can gradually get bent by the action of thermal expansion and contraction of the bed combined with spring tension. And a bent H-frame causes the linear bearings to grind and vibrate making the print look crappy and full of noise. Edit: this calibration method is for horizontal expansion equal to 0 or slicers that don't have it, like Cura 14.07. For new slicer it can be used too, but measure both inside (140mm) and outside (150mm) and use it in the way described in this object: https://www.thingiverse.com/thing:3967147