My A20M printer won't print in centre of plate after slicing with Cura

[BillAdo 0]

My A20M printer won't print in centre of plate after slicing with Cura. It Starts printing at x=0 & y=0 and only prints one quarter segment of model.  If I print the g code of the sample model supplied with the printer it prints in the centre of the plate perfectly. If I locate the model at the far right corner of the Cura platform before slicing, the printer prints the model approx centre of printer plate. Any suggestions?

[GregValiant 886]

Settings | Printers | Manage Printers | (Make sure your printer is the active printer) | Machine Settings and then DE-select "Origin at Center".

 

With a model located in the center of the Cura workspace - when you create a gcode for your printer you can open it in a text editor.  Near the beginning of the file will be lines:

;MINX:-59.762
;MINY:-28.957
;MINZ:0.2
;MAXX:59.764
;MAXY:28.954
;MAXZ:98.5

If MinX and/or MinY are negative numbers then "Origin at Center" was checked.  You can see that (MinY + MaxY) / 2 = Bed Midpoint = 0.

The only difference in the file these lines came from is that "Origin at Center" was de-selected.

;MINX:55.238
;MINY:86.043
;MINZ:0.2
;MAXX:174.762
;MAXY:143.953
;MAXZ:98.5

The math is the same  (MinX + MaxX) / 2 = Bed Midpoint = 115.  The midpoint of my bed is indeed X115, Y115.

Edited June 9, 2021 by GregValiant

[BillAdo 0]

Hi Greg,  Thanks for the very prompt reply. I can follow your reasoning but not sure what I have to do to correct the problem. There are boxes to set Min X, Max X, Min Y & Max Y in the prenter settings but no guidance on how to set them. Can I change these To correct the maths and deselect the Origin at Centre box to reset everything. 

[GregValiant 886]

Sorry I was confusing.  Just de-select origin at center.  

 

The rest of the reply has to do with determining what your actual midpoint is.  

 

The MinX and stuff on the right side of the Machine Settings dialog are the dimensions of your print head.  They are used if you enable printing "One at a Time" so Cura can tell if the print head is going to mash a finished part on the build plate.

[BillAdo 0]

Thanks, I thought it was a simple problem but not that simple!!!   I will try again and let you know.

[BillAdo 0]

Hi Greg,  yes it prints further into the plate, not the middle but far enough in for my purposes.  Shouldn't the printer use the 255mm range of the printer to come up with something like 125 for the centre and similarly for the Y centre?

[GregValiant 886]

This is where I started to go earlier...

Cura has a virtual build plate and your printer has a physical build plate.  They need to be synced so a print ends up in the middle of the physical build plate.

Your build plate looks to be 255 x 255.  Generally, you can't use the whole thing because you need some safety margin around the periphery.  The build plate is mounted on springs and so might be a little this way or a little that way.  It matters.

So figure a safety area of 2.5mm all the way around

Auto-Home the printer.

Use the LCD and move the nozzle to a point 2.5mm from the left edge of the build surface and 2.5mm from the front edge of the build surface.

Select "Set Home Offset" on the printer and then select "Save Settings".

In Cura go to the Machine Settings again and on the left under Printer Settings make the X width 250 and the Y  depth 250.

 

So the Cura virtual build surface is 250 x 250 with 0,0 in the left front corner and that will be origin for any gcode you make.  When the printer reads the gcode it will put the Cura virtual 0,0 at the Home Offset physical 0,0 position.

 

After setting your Home Offset, if you move the print head to X125 Y125 it should be really close to the midpoint of your 255 build plate.

[BillAdo 0]

I knew it wasn't as simple as I thought but I do follow you and will make the adjustments  Just for your information, I am 83 years old and still learning new tricks although I am slower than I used to be..Thanks again and I now know where to go to for "expert" help.

Bill A

[GregValiant 886]

3D printing just takes a bit of thought and knowing where to find the information.  Once the printer is set up nice and square and calibrated, the quality and accuracy of the parts can be dazzling.  Speaking of calibration - have you calibrated the Extruder steps/mm?  That needs to be done on all 3D printers (except maybe Ultimakers).

 

And I have to say that I'm pleased that there is finally someone around here that's older than me.

[BillAdo 0]

my printer is operating as it should.
 

Greg,

I bow to your superior knowledge even if you are a youngster.