Question about G92
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Hi,
I am working on my first (and perhaps last) tool changing machine.
Based on my reading and testing:
- a "plain" move like G1 Z5 is moving based on the current user position of Z
- a move preceded by G53, thus G53 G1 Z5, is moving based on the current machine position of Z
In the case where no tool is mounted the user position and the machine position appear to always be the same.
So a G1 Znnn move and a G53 G1 Znnn have the same effect.
When a tool is mounted with, say, a Z offset of -25 things get interesting or confusing depending on my state of mind.
The G1 moves with and without the G53 behave as I expect.
Now as to my question:
A G92 Znnn command appears to be setting the user position and the machine position ends up at a position based on the tool Z offset.
Is there a way to obtain the equivalent of a G53 G92 Znnn command?
The printer has a Z endstop which stops a homing move well clear of any tool that may be mounted. So I can home the machine with or without a tool mounted.
After a homing move, as expected, the machine position is what the Z min setting is - which is 0.
On a "normal" printer I would simply include in the homing code a G92 Znnn command to set the actual Z machine position.
If it was possible to do G53 G92 Znnn it would all work out fine and be simple.
However it seems I must test to see if a tool is mounted and use a Znnn value, for the G92, computed based on the tool Z offset.
Not hard but it makes the code a bit more complicated.
So I know that is a lot to read but is my understanding of it all correct? Or should I take up a new hobby?
Thanks very much.
Frederick
P.S. Maybe what I should post is a firmware request.
