Auto Bed Levelling Glitches

[MiniMadRyan]

Alright, I'm losing my mind here....this is weird...

I fired up the printer again tonight, having not modified or changed anything from last night. Connected it, and my first command was a G28. The X and Y zero'd out, and then the Z took its probe, so after it was finished, the printer was at 0,0. It did not return to the centre of the bed like before. I then ran a G29, and it ran its probing from 0,0. I ran a few more G28 and they all homed at 0,0 without returning to the centre.

I then unplugged the printer, closed Repetier and started again. the first G28 did the same thing, 0,0. A second G28 then moved the head to the centre, and homes the Z axis there. G29 Probes from roughly the middle like what was intended.

So last night I reported that it was always returning to the middle of the bed, well...I guess it's not...it still always homes at 0,0 on the first G28, and only does it return to centre on subsequent G28's.


Edit.....CSI: Bed Levelling Edition is getting stranger...here's my output from Repetier....let's have a look:

In the screenshot, you can see i've connected the printer, and it's online at 7:52:45

Screen Shot 2014-11-06 at 7.54.07 PM.jpg

At 7:52:52 I issue an G28 command. The G28 Homes to 0,0 and takes the Z probe from that location. It does not return to centre at any point.
I issue a M114 at 7:53:14, and the results are: X:93 Y:131 Z:10.00

Another G28 is run after this at 7:53:27, this time, the X,Y go to 0,0 and then return to the centre of the bed where it takes the Z probe. The G28 completes and the extruder is in the middle of the bed.
My last M114 is taken at 7:54:01 with the results of X:93 Y:131 Z:10.00

Summary?....two identical commands, two completely different results on the physical printer, and yet the output are both identical.....WEIRD!


For fun, I then ran a G29 followed by a M114, the results being X:118 Y: 156 Z:4.95, This correlates with the position of the extruder after it's done it's final probe
I ran one last G28 and M114 after that G29, the results then being the same X:93 Y:131 Z:10

Screen Shot 2014-11-06 at 8.00.28 PM.jpg

So, I think I can understand why my Y crashed last night. When the print ran, it ran a G28 as usual, the resulting physical position of the extruder was 0,0. I can only assume that the values returned were in fact X93 and Y131, which, with the bed physically being at 0, would have caused the grinding crash when it attempted to move the bed.

Last Edit.....I'm an moron...I assumed that a single G28 command was the same as manually homing each axis, either through code or Repetier's on screen controls. Apparently I was oh so wrong....I can't believe I over looked that!.....well it no longer crashes, but when it prints, the head is still far too high above the print bed.....time to play some more!

[Roxy]

Last Edit.....I'm an moron...I assumed that a single G28 command was the same as manually homing each axis, either through code or Repetier's on screen controls. Apparently I was oh so wrong....I can't believe I over looked that!.....well it no longer crashes, but when it prints, the head is still far too high above the print bed.....time to play some more!

Ah... I think it should be the same. I couldn't read the attached screen shots because they were so small. So I bumped up the size.

But if it is working except for the height of the nozzle, that is easy to dial in and get correct.

At 7:52:52 I issue an G28 command. The G28 Homes to 0,0 and takes the Z probe from that location. It does not return to centre at any point.
I issue a M114 at 7:53:14, and the results are: X:93 Y:131 Z:10.00

So you issue the G28, it moves to (0,0), measures a point and then without moving any where else, a M114 claims it is at (93,131,10) ?
It kind of looks like it isn't moving to the right place for the G28 ????