Strange axis not home error
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@fcwilt I understan this and your explanation is correct, but the thing it is not clear to me is:
if you want to probe the center of the bed, you are telling me to move the nozzle to X175+-offset and Y175+-offset so the probe is positioned at 175,175. But the machine doesnt know that, all the machine knows is she is at position X175+-offset and Y175+-offset , not at the center. That is my trouble into understanding this
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@tinchus said in Strange axis not home error:
@fcwilt I understan this and your explanation is correct, but the thing it is not clear to me is:
if you want to probe the center of the bed, you are telling me to move the nozzle to X175+-offset and Y175+-offset so the probe is positioned at 175,175. But the machine doesnt know that, all the machine knows is she is at position X175+-offset and Y175+-offset , not at the center. That is my trouble into understanding this
That is true but the data obtained when probing is from the point the probe touches - which is 175,175.
That data is only information about Z, there is no information about X or Y.
Let's say the Z Trigger Height setting in G31 is Z2.34.
When the probe, positioned at 175,175, triggers it tells the firmware the Z position at that instant was 2.34.
If the setting in G31 is correct the logical Z position (where the firmware "thinks" Z is) will match the physical Z position - which is the whole purpose of setting the Z=0 Datum, getting the logical and physical positions in sync.
Having established the logical Z position all subsequent Z moves should be accurate so, for example, a move G1 X175 Y175 Z0 should result in the nozzle just touching the bed at 175,175.
If it does that you know that the G31 setting is correct, which is essential to creating accurate height maps.
Frederick
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@fcwilt said in Strange axis not home error:
That is true but the data obtained when probing is from the point the probe touches - which is 175,175.
OK! Then this is the answer I was looking for. Following you explanation, the the formware is actually taking into account the probe offset when I tell it to probe the bed.
