How to calibrate the print center??

Hi
Im having trouble getting the print central on the heatbed on my i3, the X axis isnt that far out but the Y axis is to far back, im guessing it has something to do with the fact that the Y endstop is right at the back, but i cant really change that as the endstop holder is built into the motor mount. Im sure im probably missing something really simply but if someone could point me in the right direction i would be grateful

Your center is set in your slicing program. The corner you home to is 0,0,0. The center is put in relative to the home.

i think im being abit dense, when i place the object in the center of slicer and set it off printing its off center on the heatbed, i homed the X / Y axis and then manually moved it into dead center of the bed using repetier host and to get it in the center i have to move X = 103mm and Y 139mm, i figure that value has to be entered somewhere, perhaps in the firmware?

When you set up Slic3r you enter the 103 and 139 under the printer settings tab, general sub section, under Print Center X and Y (second item from the top of the frame).

All that's on the latest version. They tend keep things in the same general locations between versions.

I had a similar problem with my ReprapPro Mendel and I had to fiddle with the offsets set by the G10 command to get it correct. This is the procedure that I used :-

1)Set up the offset for the primary extruder ( I have 3 extruders in mine) using M206 x Y such that when you issue G1 X1 Y1 F
the primary extruder noxzzle is over the bed position of X1 Y1 then save it with M500.
2)Set up the offsets for each extruder relative to this location using G10 P X Y Z so that my test object printed in the center of the bed.
Where:-
P is the extruder number starting at 0,
X is the X offset relative to the origin,
Y is the Y offset relative to the origin
Z is the z offset (on my Mendel this is always 0 because it is set by the end stop).

Thus for extruder 0, an X offset of 5, and a Y offset of -21 you issue:-G10 P0 X5 Y-21 Z0.
When you have got the values correct, dont forget to save them with M500.

I used a thin, cube about 10mm square as a test piece and kept varying the values and printing the cube until I got what I wanted. I found it useful to set up a spreadsheet in which I entered the offsets I had issued, and the position over the bed that resulted from this and it took quite a bit of fiddling until I got the cube to print in the center of the bed.

Hope this helps

Harvey

Edited 1 time(s). Last edit at 11/29/2013 11:37AM by HarveyC.

am using pronteface all i do to find the center is home the printer, manually move the nozzle till its over the thermistor in the center of the heatbed ,enter M114 (marlin F/ware) and "bob's yr uncle " the value off the axis is returned

Hi, thanks for the replies, i went into slic3r settings in Repetier-Host and and change the print center for X = 103 and Y = 139 and saved the settings, i then tried to print an object in the center of the heatbed and it printed in the front middle of the heatbed, i was abit puzzled by this as it should have printed in the middle, its as if the bed isnt moving far enough forward, so i altered the print center settings for Y to be 239 and then repeated the same print, to my surprise, it again printed front middle, its like its not seeing the changes i make to the print center settings and i have no idea what to try next