XL Calibration Tools

I have found the automatic tool offset calibration to occasionally unreliable so I made a few test prints to help dial in the X,Y and Z offsets for each tool. I made these to be as simple as possible so it only takes a few minutes to print. I can usually get everything within .05mm using these.  Calibrating based on the actual print dimensions is fundamentally going to be more accurate than touching off on the nozzle surfaces.

I would recommend using these if you are using small nozzles, or mixing small nozzles with large nozzles as any offsets will be more obvious.

X/Y Calibration

This is a pair of jagged lines similar to the official calibration tool, except I am giving you the 3mf file so you can slice for different nozzle sizes.  The pitch of the top line is .05mm less than the bottom line so it forms a vernier scale of sorts.  Always set the bottom line to be Tool #1 as all offsets are relative to tool 1 (there are no offsets to adjust for T1), and use the tool you are calibrating for the top line.  If the tool is aligned with T1, the center points of the patterns will be aligned.  If not, find the best aligned pair (I find this is easier done using a phone picture).  Multiply the number of points off from the center you are by .05mm and that is change you need to make in your offset, see example. I find this very counter-intuitive, but the offset entered into printer is the observed offset relative to T1.  So in the example below, T3 is printing with a +0.1 offset relative to T1.  So whatever the current X-offset is for T3, you would go in and increase it by 0.1mm, and then T3 and T1 would be aligned.  I will sometimes print without the wipe tower to reduce time and material; its messy but usually still functional.

Same process for Y, just make sure you are aware of which direction is +Y.

Z Calibration

This is just a simple 2 material height block. In PrusaSlicer, set the main portion of the model to Tool 1, and the tool you are calibrating to the 2 small blocks.  This allows for an easy caliper measurement of the height difference, regardless of which tool is higher.  You can also just eyeball it using a straight edge and backlight, usually the smallest discernible difference is about .05. An obvious but still small difference is about 0.10.  I do find a wipe tower is required to get a clean top surface.

Same as the X/Y offsets, you need to adjust the current offset by the observed offset relative to T1.

In the example below, I adjusted the Z-offset by +.15.

Cal check

This is a simple calibration check I will print alongside large prints so I can check that the tools are aligned so I don't find out 20 hrs into a print when a tool is first used.  There is a slight gap between the center and the frame.  If you are dialed in you should see light the whole way around the center portion if you hold it to a light (or it will separate when removed the bed). You can also use it as a rough check of tool height based on thickness and first layer quality.

In the figure below I used a +.05 X,-.05 Y offset to improve the calibration of this tool (angled corner is towards the origin). 

Full Calibration Set

This a setup for full calibration of all tools in X,Y and Z.  I don't usually use the whole thing but it is an easy starting point and you can disable what you don't need.