I've upgraded my Anet A8 stock hotend to the E3D v6. The mounting for the hotend is slightly different, so that the printer isn't correctly centered to the bed. When printing small things their isn't any problem, but when I wanted to print things that nearly take the hole buildplate it can be tricky to align the things so that they are printed fully on the platform not midair.
These instructions should help you edit your Start-Gcode to counteract this problem.
I have an Anet A8, this tutorial will most likely also work for your printer, if it runs Marlin Firmware. For slicer I am using Cura 3.1.0, in different Versions or slicers this process may be different.
My solution works good, but you should change the offset in Firmware. Than the printer has the offset stored in his memory so that the printer knows this offset not only your currently printing part. There is an Tutorial for this https://www.thingiverse.com/thing:2280529 by thingiverse user 0scar.
Firstly you should mark where the center of your bed is. Then you can print the part with the settings you have currently in your slicer. It's a very simple print, shouldn't take more than a minute.
Secondly measure what the offset is that you got (in mm). Make notes of them and open your slicer. To change the Start-Gcode go to the Machine Settings. (In Cura: Settings -> Printer -> Manage Printers -> Machine Settings).
You need to add two lines of Code to the Start-Gcode textarea in the bottom left corner. First
G21, to use the metrical system (mm). Then you need to add
G92 X18 Y-3 to offset the center. Replace "18" and "-3" with your measurements.
If your printed y-axis is under the actual y-axis center you need to make an minus in front (like in my case). If your X-axis is left to the x-axis center also make a minus in front of x-value. Hopefully you get the point.
Slice the cross again now with the new Start-Gcode. If you are lucky your measurements where correct and the cross should now be in the center directly over your markings.
Please give this project a like to show me that you liked it and comment.
My complete Start-Gcode
G21 ;using mm not inches
G92 X19 Y-3 ;Offsetting the center
G1 Z15.0 F3000 ;Move the z-axis to 15 mm
G1 F200 E3