struggling to set correct bed size

I'm trying to get my printer to use the full extent of the bed and I'm having problems.

this is what I've done so far..

// The size of the print bed
#define X_BED_SIZE 220
#define Y_BED_SIZE 220

// Travel limits (mm) after homing, corresponding to endstop positions.
#define X_MIN_POS 0
#define Y_MIN_POS 0
#define Z_MIN_POS 0
#define X_MAX_POS X_BED_SIZE
#define Y_MAX_POS Y_BED_SIZE
#define Z_MAX_POS 600

G1 X110 Y110 is quite far off centre. moving the hot end manually its at X118 and Y141 is centre on the print bed.

So I set M206 to the new coordinates. After a little trial and error M206 X-8 Y-30 gives dead centre with G1 X110 Y110.
G1 X0 Y0 also takes me to exactly the bottom left corner.

G1 X220 Y220 will only take the hot end to X212 Y190. I presume this is because I have set the home offset to -8 and -30. So Now do I increase the bed size to X228 Y250 so I can get to the top right corner?

Doesn't seem right somehow?

Draw a diagram of the machine- show the motion limits of the extruder and show where the outline of the bed is within that space. Mark the locations of the endstop switches. Pick the location of the origin. Mark the coordinates of the corners of the bed, coordinates of the limit switches, and the coordinates of the limits of motion. From that it should be easy to figure it out.

I suggest you set the origin to the center of the bed. That makes it very easy to switch from one slicer to another without having to mess around with custom gcode to get prints dropped on the center of the bed.

Make sure you use right-hand-rule coordinates or your prints will be mirrored.

More: [drmrehorst.blogspot.com]

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

That certainly looks like a good solution for switching between multiple printers/slicers. But I feel like it may be over complicated for my needs - I have one printer and one slicer.

the method I used is here [reprap.org] (method 2).

I have set the print bed size in firmware. Configured the offset with M206 so that X0 Y0 is exactly on the corner of the bed, and X110 Y110 is exactly in the middle.

for some reason G1 X220 and Y220 seem to be stop at the bed size minus offset. G1 X220 will only go to X190, which is exactly the bed size minus offset.

Whether you realize it or not, you're using my technique, you just haven't thought about it. It's much easier and less confusing if you simply draw the diagram and mark the coordinates that you want. You can apply the same technique to putting the origin at the corner of the bed.

Putting the origin at the center of the bed now will make it easier to use other slicers in the future. It doesn't cost anything to do it, and it will work with whatever slicer you're using now. Other wise, in the future, if you want to try another slicer, you may end up going through all this again. What's more complicated, doing it right once, or doing it multiple times and never being sure about what you're doing?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I disabled

// #define MAX_SOFTWARE_ENDSTOP_X 
// #define MAX_SOFTWARE_ENDSTOP_Y

and it seems to be working.

these commands now take the probe to the correct position of the bed (bottom left, centre, top right)

G1 X0 Y0 
G1 X100 Y100
G1 X220 Y220

It would seem the software endstops are being calculated from G28 home, not home offset. This might be a bug?

Now I have another issue. AUTO_BED_LEVELING_LINEAR probes off the back of the bed. Front and middle probe positions are fine.

I have the probe offset correct. (Probe is 80mm directly behind nozzle.

#define NOZZLE_TO_PROBE_OFFSET { 0, 80, 0 }
#define MIN_PROBE_EDGE 25

Edited 2 time(s). Last edit at 05/03/2020 07:08PM by nick9one1.

 *
 * - AUTO_BED_LEVELING_BILINEAR
 *   Probe several points in a grid.
 *   You specify the rectangle and the density of sample points.
 *   The result is a mesh, best for large or uneven beds.
 *

I cant see where in configuration.h I set " You specify the rectangle and the density of sample points."

All the advice online seems to be out of date as the code has changed but found some additional config in _adv

#if EITHER(MESH_BED_LEVELING, AUTO_BED_LEVELING_UBL)
  // Override the mesh area if the automatic (max) area is too large
  //#define MESH_MIN_X MESH_INSET
  //#define MESH_MIN_Y MESH_INSET
  #define MESH_MAX_X X_BED_SIZE - (MESH_INSET)
  #define MESH_MAX_Y Y_BED_SIZE - (MESH_INSET)
#endif

changed to

#if EITHER(MESH_BED_LEVELING, AUTO_BED_LEVELING_UBL)
  // Override the mesh area if the automatic (max) area is too large
  #define MESH_MIN_X 25
  #define MESH_MIN_Y 5
  #define MESH_MAX_X 220
  #define MESH_MAX_Y 140 
#endif

Edited 1 time(s). Last edit at 05/04/2020 05:01AM by nick9one1.

EEPROM probe offset was my problem all along.

fixed with M851

Edited 1 time(s). Last edit at 05/04/2020 08:14AM by nick9one1.