Delta Distortion Correction Head is moving too high

ebrithil

Hello,
When I use the G33 command, the printer homes, then moves all the way down. But then he moves too high up again and starts the probing-process but after two probes he stops and gives this error:

18:23:08.203: Warning:Invalid delta coordinate - move ignored x:-61373 y:76177 z:11784

18:23:08.207: Warning:in queueDeltaMove to calculateDeltaSubSegments returns error.

18:23:08.215: Warning:moveToReal / queueDeltaMove returns error

18:23:18.533: Z-probe:20.603 X:-74.17 Y:71.27

18:23:18.537: Error:Bpos x square

18:23:18.547: Warning:Invalid delta coordinate - move ignored x:-47806 y:90333 z:11631

18:23:18.551: Warning:in queueDeltaMove to calculateDeltaSubSegments returns error.

18:23:18.559: Warning:moveToReal / queueDeltaMove returns error

18:23:22.839: Z-probe:17.564 X:-74.17 Y:71.27

18:23:22.843: Error:Stopping distortion measurement due to errors.

18:23:22.847: RequestStop:

18:23:23.365: fatal:G33 failed! - Printer stopped and heaters disabled due to this error. Fix error and restart with M999.

Also at the beginning of the process he shows this line whitch I don't understand how he get on this value:

18:23:08.195: Reference Z for measurement:20.000

Here are the parameters for Distortion Correction for my Delta:

#define DISTORTION_CORRECTION 1
#define DISTORTION_CORRECTION_POINTS 5
#define DISTORTION_LIMIT_TO 2
#define DISTORTION_CORRECTION_R 150
#define DISTORTION_PERMANENT 1
#define DISTORTION_UPDATE_FREQUENCY 15
#define DISTORTION_START_DEGRADE 0.5
#define DISTORTION_END_HEIGHT 1
#define DISTORTION_EXTRAPOLATE_CORNERS 0
#define DISTORTION_XMIN -100
#define DISTORTION_YMIN -100
#define DISTORTION_XMAX 100
#define DISTORTION_YMAX 100

#define Z_PROBE_HEIGHT 0.409
#define Z_PROBE_BED_DISTANCE 3

I hope someone can help me.

ebrithil

Ok I got it figured out so far, with these settings it seemes to work for no obvious reasons:

#define DISTORTION_CORRECTION 1
#define DISTORTION_CORRECTION_POINTS 7
#define DISTORTION_LIMIT_TO 2
#define DISTORTION_CORRECTION_R 75
#define DISTORTION_PERMANENT 1
#define DISTORTION_UPDATE_FREQUENCY 15
#define DISTORTION_START_DEGRADE 0.5
#define DISTORTION_END_HEIGHT 1
#define DISTORTION_EXTRAPOLATE_CORNERS 1
#define DISTORTION_XMIN -75
#define DISTORTION_YMIN -75
#define DISTORTION_XMAX 75
#define DISTORTION_YMAX 75

And also for a strange reason, the firmware uses the ZHOME_HEAT_HEIGHT value if its bigger than z probe distance to set the distortion distance, whitch makes no sense to me.

But now I have another problem, the measurement works fine but it actually makes printing much worse than before, I don't think hes calculating something right because it lifts the head up on places even more than before.

Repetier

Correct usage is something like this
G28
G1 Z10 ; so z probe is enough above bed
G32 S2
G1 Z10
G33

Afterwards you can see with
G33 L0
if the values swing around 0. Also remember that G33 should only be used after geometry is calibrated. If you have differences of more then 0.1mm optimize geometry instead. G33 reduces correction over height normally (on deltas you might want to disable this reduction since the error might come from geometry error and thus stays the same over Z).