Issue converting bed.g to use Conditional gcode

gtj0

A quick experiment revealed that if the M671 S limit is reached, no correction is done at all so it can't possibly converge by running multiple times. The only way out would be to manually move the screws until the correction would be inside the limit.

fcwilt

@gtj0 said in Issue converting bed.g to use Conditional gcode:

A quick experiment revealed that if the M671 S limit is reached, no correction is done at all so it can't possibly converge by running multiple times. The only way out would be to manually move the screws until the correction would be inside the limit.

It seems that something may have changed since I last used auto-leveling. Back then it made the max adjustment it could and multiple runs kept improving things.

Frederick

gtj0

I thought it did as well which is why i tested it. I set my limit to 1mm and manually moved 1 screw so it would need at least 3mm then ran G32 S3. It probled the 3 points but returned Some computed corrections exceed configured limit of 1.00mm: -0.219 3.092 -1.290 with no movement.

Bear in mind, I'm using RRF3 via the DSF/SBC. It may be different in standalone mode. I can check that in a bit.

gtj0

Nope, no change in standalone mode...

M671 X-23:238:498 Y13:485:13 S1
ok
G28
ok
G32 S3
Error: Some computed corrections exceed configured limit of 1.00mm: 0.935 -3.386 -2.561
G32 S3
Error: Some computed corrections exceed configured limit of 1.00mm: 0.939 -3.385 -2.561

gtj0

@dc42 : Bug?

A Former User

@gtj0 it can be a bug or a feature depends on how the G32 was designed by author
to me it looks like it's intentional to do not do any correction if discrepancy is larger by limit set by M671Sxxx. I'd too probbly do it exactly like that but would be cool to have a separate parameter for M671 to "do max x mm of adjustment" in order to be able to do what you want (adjust only 1mm then measure again, adjust 1mm max, measure etc etc.. ) ... but I'd keep Sxxx limit as a "hard one" as if "too badly missaligned" or "damaged probe" or "$h1t on the print bed you are probing over" trying to fix it could be damaging to the printer itself

Danal

@gtj0 said in Issue converting bed.g to use Conditional gcode:

The only way out would be to manually move the screws until the correction would be inside the limit.

Or chose to configure a larger limit. M671 S10.

Only you can know what limit represents "this is about to damage the printer" vs. "OK to adjust this large amount".

tekkydave

@gtj0 said in Issue converting bed.g to use Conditional gcode:

A quick experiment revealed that if the M671 S limit is reached, no correction is done at all so it can't possibly converge by running multiple times. The only way out would be to manually move the screws until the correction would be inside the limit.

That's what I've found.

tekkydave

@fcwilt said in Issue converting bed.g to use Conditional gcode:

@gtj0 said in Issue converting bed.g to use Conditional gcode:

A quick experiment revealed that if the M671 S limit is reached, no correction is done at all so it can't possibly converge by running multiple times. The only way out would be to manually move the screws until the correction would be inside the limit.

It seems that something may have changed since I last used auto-leveling. Back then it made the max adjustment it could and multiple runs kept improving things.

Frederick

Yes, I thought it worked that way but obviously not.

tekkydave

Thanks for all the helpful comments. Just to say I have no issue with the way G30 works although the option to move by a limited amount per session would be a nice to have.
My issue is about the example code which seems to suggest it can iteratively home in when it can't.

I usually have my limit at 3mm which works fine and to be fair G30 usually achieves a deviation of 0.0 on my D-Bot first time it runs.

droftarts

@tekkydave said in Issue converting bed.g to use Conditional gcode:

My issue is about the example code which seems to suggest it can iteratively home in when it can't.

"if calibration yields a standard deviation that is above a limit, it repeats the calibration process"

From https://duet3d.dozuki.com/Wiki/GCode_Meta_Commands#Section_Using_conditional_GCode_commands_in_bed_g_to_calibrate_a_delta_printer

I think you have misinterpreted what the 'limit' is; it's not the hard limit imposed by M671, it's the limit set in these lines:

if move.calibrationDeviation.deviation <= 0.03
break
echo "Repeating calibration because deviation is too high (" ^ move.calibrationDeviation.deviation ^ "mm)"

ie 0.03mm. If the calibration is more than 0.03mm out, it repeats it for up to 5 times.

Ian

tekkydave

@droftarts said in Issue converting bed.g to use Conditional gcode:

@tekkydave said in Issue converting bed.g to use Conditional gcode:

My issue is about the example code which seems to suggest it can iteratively home in when it can't.

"if calibration yields a standard deviation that is above a limit, it repeats the calibration process"

From https://duet3d.dozuki.com/Wiki/GCode_Meta_Commands#Section_Using_conditional_GCode_commands_in_bed_g_to_calibrate_a_delta_printer

I think you have misinterpreted what the 'limit' is; it's not the hard limit imposed by M671, it's the limit set in these lines:

if move.calibrationDeviation.deviation <= 0.03
break
echo "Repeating calibration because deviation is too high (" ^ move.calibrationDeviation.deviation ^ "mm)"

ie 0.03mm. If the calibration is more than 0.03mm out, it repeats it for up to 5 times.

Ian

Not what I found. G30 exits if the limit in M671 is exceeded without getting to the test.

droftarts

@tekkydave ANY G30 bed levelling exits if it exceeds the deviation limit set by M671, whether it's called in conditional gcode or a manual bed levelling. If you'd rather M671 issued a warning and attempted to level, rather than exiting, you'd best ask @dc42 for that functionality.

Ian

tekkydave

@droftarts said in Issue converting bed.g to use Conditional gcode:

@tekkydave ANY G30 bed levelling exits if it exceeds the deviation limit set by M671, whether it's called in conditional gcode or a manual bed levelling. If you'd rather M671 issued a warning and attempted to level, rather than exiting, you'd best ask @dc42 for that functionality.

Ian

I'm ok with how G30 works and I understand what you mean about the "real" test being the 0.03. I just wanted to point out that the example needs a line explaining that it will only work within the limit you have set in your M671 command. Most users would have left this at the default of 1mm. If you have disturbed one of your leadscrews by more than 1mm you will need to manually level the bed before running the macro.

dc42

Currently, if calibration fails then move.initialCalibrationDeviation and move.finalCalibrationDeviation are not changed. I'll change this in beta4 so that they are both set to the measured initial deviation. Also I'm thinking of moving them to a separate move.calibration section.

droftarts

@tekkydave I've just realised the example code is for a delta printer, which doesn't use M671 (no leadscrews) to limit correction, so hasn't been considered in the description or writing of the code. I've updated the page to reflect this.

NOTE: If you use this method to iterate the levelling of a bed/gantry mounted on leadscrews (eg Cartesian, CoreXY etc), the maximum deviation corrected is still limited by the S parameter of M671 (default 1mm). If the maximum deviation exceeds this limit, the script will exit with "Error: Some computed corrections exceed configured limit of 1.00mm", as it would if G30 bed levelling was called manually.

https://duet3d.dozuki.com/Wiki/GCode_Meta_Commands?revisionid=HEAD#Section_Using_conditional_GCode_commands_in_bed_g_to_calibrate_a_delta_printer

Ian

tekkydave

@droftarts said in Issue converting bed.g to use Conditional gcode:

@tekkydave I've just realised the example code is for a delta printer, which doesn't use M671 (no leadscrews) to limit correction, so hasn't been considered in the description or writing of the code. I've updated the page to reflect this.

NOTE: If you use this method to iterate the levelling of a bed/gantry mounted on leadscrews (eg Cartesian, CoreXY etc), the maximum deviation corrected is still limited by the S parameter of M671 (default 1mm). If the maximum deviation exceeds this limit, the script will exit with "Error: Some computed corrections exceed configured limit of 1.00mm", as it would if G30 bed levelling was called manually.

https://duet3d.dozuki.com/Wiki/GCode_Meta_Commands?revisionid=HEAD#Section_Using_conditional_GCode_commands_in_bed_g_to_calibrate_a_delta_printer

Ian

Thanks I realised the code was for a delta but adapted it to the commands I normally used in bed.g. I didn't know delta's don't use M671 so to me for using it in the wrong context. I was keen to have a play with conditional g-code.
Dave