need help to center object and set a Park position

Thanks to all that have helped us and hope we can contribute as well.

Our set up is a new Aurora Z605 Prusa I3, Melzi 2.3 controller board, Arduino IDE, Marlin firmware, Repeiter Host software.

We have not been able to set up the firmware to "park" the Extruder Nozzel at any position other than at the X, Y, X stops against the mechanical limit switches.

Additionally we are having difficulty setting a "center" position on the heated print bed.

Any direction would be greatly appreciated,

Thank you

Nick001

There is a good reason to park the nozzle at the "all home" position. Since you are using stepper motors, the printer really only knows where the all home position is, and not REALLY where the print head is at any other time. It might know that it TOLD the motor to move the print head to position X/Y/Z but it doesn't actually know if it happened, and if you reset the printer, it no longer knows where it is at all. The home position is the only time that it really knows where it is, and is generally the best place to rest.

Centering the printed object on the print bed is the job of the slicer application. If you know the actual dimensions of the printable area, and you know that the stops are positioned appropriately, then you can tell the slicer where the center of your print bed is, and it will generate G code appropriate to that purpose. I kind of tweaked my settings in slic3r until I got reasonable results, though since my Y axis home moves a bit whenever I adjust belt tension, it's never perfectly centered, but it's okay.

The area that the print head can physically move to is larger than the actual print bed, I find. I choose to limit in software not to print outside the heated area of the print bed.

Hi Supra,

Thank you for the reply.

You make an excellent point as the printer has no "feedback" mechanism in hardware or software, position is always relative from its last position, so your indicating that the mechanical/physical Home, is the only reliable "calibration".

This is not trivial, which you point out, as the "system" needs the physical stability with the frame, rails and bearings to be "stable" as possible.

So, the centering is as you indicate is handled not in the firmware but in the SLICER CAM software.

Excellent and thank you,

Nick