On the Tronxy X3 the home position is off the print bed. It's about 20 mm to the left of the bed, and about 40 mm in front of the bed. But the home position is x=0, y=0 on the printer.
By default, Repetier-host sets up with the front left corner of the print bed at (0,0). But as I just said, (0,0) on the printer isn't at the front left corner.
To fix this, do the following:
Find the X coordinates of the left and right sides of the print area
Turn on your printer. Using the Buttons and the LCD panel, home all the axes. Then, using the LCD panel Position/X Pos. Fast menu item, move the head until the extruder is at the left end of the desired printing area. For me, that's a little to the right of the edge of the table. Read the X position (in my case, 23.00 mm).
Then move to the right of the desired printing area. In my case, 223.0 mm. Note that it's 200 mm greater than the left end, which is what I expect.
Find the Y coordinates of the front and back of the print area
Repeat the process for the Y axis (making sure the extruder nozzle clears the print bed). For me, the front of the print area was 34.00 mm, and the back of the print area was at 230.0 mm (this appeared to be a hard limit set in the firmware, as the carriage hadn't hit a physical stop, and the nozzle wasn't at the back of the print area. Later on, I'll try to adjust it in the firmware.) So to keep the full 200 mm of travel in the Y direction, I will set the front of the print area to 30.0 mm.
Enter the settings into Repetier-host
Click on printer settings in Repetier-host. Enter 0 for the X min and the Y min. Enter the maximum numbers you found in the previous steps for X max and Y max (223 and 230 for me). Set the width and depth of the print area to 200. Set the Bed Front to the value obtained in the previous step (30 mm for me). Set the Bed Left to the left side X value found above (23 mm for me).
Now you're ready to go! Make sure that slicer is set to 200 mm by 200 mm, with the origin at (0,0). Make sure your STL files get placed in the center of the work area (use the Center Object button on the Object Placement panel if necessary). Now you should have your objects right in the center of your bed. And most importantly, the bed in the Object Placement panel accurately represents your printer bed.
Happy printing!
