G43.1 Dynamic Tool Length Measurement - Program Exceeds machine maximum on axis

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29 Nov 2021 17:48 #227932 by harry4516
I understand what you explain, maybe this is an issue only in Axis-GUI. I'm using qtdragon and don't have a problem with boundaries check.
Anyway, boundaries check should only be done against the machine limits. G43.1 changes (at least in qtdragon) only G45 coordinates, not machine coordinates. In your code above you are mixing machine limits with tool length which could cause problems. But, I don't use axis, so maybe its different there.

Back to the limit problem of the tool-change code.
The calculation with variables #2002 and #2003 is not working correctly. Usually they are the same and don't have any effect. But as these are global variables they could get a value from somewhere else and then the strangest things happen. I have tested it for a week and never got reliable results, including the limit problem discussed here.

I have changed the code into two files, one for reference measurement and the second for use (M6) during normal operation.
Maybe it is useful for somebody, its attached here. We are using it for a few days and didn't have any more problems.
 
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01 Dec 2021 19:22 #228144 by +Jan+
Good evening,
thanks for the macros, I will have a look. 

The calculation with variables #2002 and #2003 is not working correctly. 


I can't confirm this, as long as no other macro uses the same parameters there should be no problems. The tool measurement works stable for me with the code since weeks. After I have measured the tool after starting Linuxcnc I set Z0 to sacrificial plate level with another macro (see attachment) or manually to another point. When I do this, there are no problems except for the faulty preview (which also shows up with an empty remap file). I hope to get around to experimenting with D2inventory's hints in the next few days.

Best regards

Jan 

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File Name: messen_z.ngc
File Size:1 KB
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20 Apr 2022 11:41 #240730 by andypugh

if o.canon.max_extents_notool[i] > machine_limit_max[i]:
to:
[code]if o.canon.max_extents_notool[i] + (o.last_tool_offset[i] / 25.4) > machine_limit_max[i]:[/i][/i][/i]
[/i][/i][/code]
 

This seems to be something missed as G43.1 was introduced some time after Axis was completed. 

Did you create the pull request? I think that units conversion is handled by some functions in the axis code:
github.com/LinuxCNC/linuxcnc/blob/master...scripts/axis.py#L285


 

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01 Jul 2022 11:21 #246350 by d2inventory

Did you create the pull request? I think that units conversion is handled by some functions in the axis code:
github.com/LinuxCNC/linuxcnc/blob/master...scripts/axis.py#L285



I have now :D

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01 Oct 2023 23:01 #282034 by andypugh

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02 Oct 2023 13:07 #282062 by andypugh
The behaviour can probably be explained by this sequence


The G-code extents are calculated at the point that the G-code program is loaded, using the tool-length data that was current at that point.

When the run button is pressed the system checks the G-code extents, unaware that the tool length might have changed.

In the scenario described, if you were to press the "cancel" button, reload the g-code and then press "run" again the calculation should be correct.

The "fix" here is wrong, apart from anything else it can only use the data from the last tool loaded, so can not be correct for any program with multiple tools used.

The max/min_extents_notool[] data already includes the effect of tool lenght offsets (it's the raw position of the spindle inside the axes, the version without the "notool" is the position of the tool tip inside the axes.)
The following user(s) said Thank You: +Jan+

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23 Oct 2023 14:22 #283604 by +Jan+
I actually always get the message, regardless of whether the tool used in the program has already been measured or not. In addition, it is inconvenient if I always have to click away a dialog box, since I actually use a hardware start button that is not bound to the monitor.

Therefore, I changed today on good luck - I am no coder - a small thing at the code. Now limit violations of the Z-axis are ignored in the function. In X&Y the check still works. Since the tool length does not change exactly predictably with every tool change anyway, I can accept that I have to take a look at it myself.

Here the original definition (from an older 2.8 master version)
def run_warn():
    warnings = []
    if o.canon:
        machine_limit_min, machine_limit_max = soft_limits()
        for i in range(3): # Does not enforce angle limits
            if not(s.axis_mask & (1<<i)): continue
            if o.canon.min_extents_notool[i] < machine_limit_min[i]:
                warnings.append(_("Program exceeds machine minimum on axis %s")
                    % "XYZABCUVW"[i])
            if o.canon.max_extents_notool[i] > machine_limit_max[i]:
                warnings.append(_("Program exceeds machine maximum on axis %s")
                    % "XYZABCUVW"[i])
    if warnings:
        text = "\n".join(warnings)
        return int(root_window.tk.call("nf_dialog", ".error",
            _("Program exceeds machine limits"),
            text,
            "warning",
            1, _("Run Anyway"), _("Cancel")))
    return 0

The only line I changed is this:
 for i in range(2): # check only for x & y violations

Best wishes

Jan

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