Hi, I’ve had a 3d printer for sometime. It started out as a Anet A8 but has been greatly modified. I now have a Re-Arm control board and a BLTouch. I have been able to get things working for the leveling matrix but when slicing with Cura the x and y axis for the extruder are not centered on the build plate and I can not figure out what to do to correct it. I’ve tried changing things in both the config and the config-overide file but that messes with the probe matrix. If anyone can help I will send them both files. Cura doesn’t allow you to input an offset for the center of the build plate.
Sounds like you have the printer dimensions wrong in Cura. Home the axes, then use the manual controls to move the axes in 10mm increments to their respective maxima (or to the point where the nozzle goes off the side of the platform). You could also mark the minimum and maximum locations on your platform and measure the distance between them. Input these dimensions into Cura, and it will place the center at half of each value.
Of course, if your nozzle is offset such that it can’t actually reach one side of the platform, then some of the platform isn’t usable area, and prints will be placed in the center of the usable area, rather than the physical center of the platform. There’s not much to be done about that. If you want to physically center it on your platform, you’ll have to offset it manually.
Another thing to consider is the shape of your object. Cura determines the “center” of your object using its bounding box. This means that if you bring in an object that is roughly triangular, one or two points of the triangle will usually seem to stick out too far. This is because the center of a triangle isn’t in the same place as the center of the smallest rectangle it will fit inside.
This bounding box system is actually what you want for a rectangular platform, since centering a triangular object using its bounding box will place its leftmost point the same distance from the left edge of the platform as the rightmost point from the right edge of the platform, even if it makes it look off-center. It can be frustrating for deltabots though, which have circular platforms, because if you try to center a triangular object that takes up most of the platform, it will look like it doesn’t fit until you offset it manually.
The probe stays within the boundary’s of the 220x220 bed doing a 4x4. Cura is set at 220x220 but it prints only in quadrant 1. It is about 28mm right of center and 18.5mm back from the front of the plate. I was able to goto the extruder tab in printer setup for Cura and get the Y axis centered, however; I would need to enter a negative number to center the X axis which Cura doesn’t allow. The probe is the same distance in on both the X and Y axis so it is centered. The extruder has enough room to extend beyond the X axis on the right side of the plate by 28mm.
I figured it out after doing the probe matrix I had to add the following to the end of my start code. Changing any X Y offset in either the config or config.override file would throw the probe matrix off.
G28 X0 Y0 # home x y
G92 X-15 Y0 # set the x y offset