Hello,

in some circumstances I get faceted arcs even if "arcs to segments" is disabled. (Maybe it's not faceted, it's difficult to tell whether they are facets or other artifacts that make it look like it was faceted.)

example of a circumstance triggering the problem:

using KmotionCNC 4.34h

units mm

problem arc is:
starting point X13.3343 Y47.6702
G3 X0.0 Y49.5 I-13.3343 J-47.6702
G3 X-13.3343 Y47.6702 I0.0 J-49.5

using these feeds I get the artifacts:

F40.8
F89.1
F123.75
F129.6

using these other feeds I do NOT get the artifacts:

F137.7
F145.8
F153.9
F148.5

Long description of the problem:

It happened first a couple months ago, all the arcs of the workpiece were correctly machined as arcs except the arc with the larger radius, which was "faceted". I failed to report it on this list but now it just happened again with a different workpiece.
Again, "arcs to segments" is disabled but the arc having the larger radius in the workpiece looks like is faceted (it's the arc reported above).

I suspect it is a numerical problem affecting certain combinations of feed and radius. This time I did repeated testing (I had several workpieces to do) and could see that the problem happened with certain feeds but didn't happen with slightly faster feeds.

I also considered it could be some instability problem of my badly tuned servos, but then I'd expect the artifacts to happen more randomly. These happen very regularly instead, and happen exactly in the same places at different "Z" heights.
I was doing "2D 1/2" parts, contouring on the XY plane and repeating same contour at different Z levels.
At you end you get perfect "vertical stripes" i.e the "faceting" happened exactly in same positions at each Z height, looking much more like something generated by the software in exact same positions at each Z level, than some random vibration of the servos (which I'd expect to happen differently at each Z height).

Please note that it may be weeks/months before I have to machine again these same parts so even if a fix is made, I won't be able to give feedback immediately....

Thank you
EC

Hi EC,

Please post your Tool Setup | Trajectory Planner Settings.

Also your Initialization C File.

How much would you estimate the "facet" path deviates from the
theoretical arc path?

Regards

TK

On 2017-04-30 05:04, ericnc@... [DynoMotion] wrote:
> Hello,
>
> in some circumstances I get faceted arcs even if "arcs to segments" is
> disabled. (Maybe it's not faceted, it's difficult to tell whether they
> are facets or other artifacts that make it look like it was faceted.)
>
> example of a circumstance triggering the problem:
>
> using KmotionCNC 4.34h
>
> units mm
>
> problem arc is:
> starting point X13.3343 Y47.6702
> G3 X0.0 Y49.5 I-13.3343 J-47.6702
> G3 X-13.3343 Y47.6702 I0.0 J-49.5
>
> using these feeds I get the artifacts:
>
> F40.8
> F89.1
> F123.75
> F129.6
>
> using these other feeds I do NOT get the artifacts:
>
> F137.7
> F145.8
> F153.9
> F148.5
>
> Long description of the problem:
>
> It happened first a couple months ago, all the arcs of the workpiece
> were correctly machined as arcs except the arc with the larger radius,
> which was "faceted". I failed to report it on this list but now it
> just happened again with a different workpiece.
> Again, "arcs to segments" is disabled but the arc having the larger
> radius in the workpiece looks like is faceted (it's the arc reported
> above).
>
> I suspect it is a numerical problem affecting certain combinations of
> feed and radius. This time I did repeated testing (I had several
> workpieces to do) and could see that the problem happened with certain
> feeds but didn't happen with slightly faster feeds.
>
> I also considered it could be some instability problem of my badly
> tuned servos, but then I'd expect the artifacts to happen more
> randomly. These happen very regularly instead, and happen exactly in
> the same places at different "Z" heights.
> I was doing "2D 1/2" parts, contouring on the XY plane and repeating
> same contour at different Z levels.
> At you end you get perfect "vertical stripes" i.e the "faceting"
> happened exactly in same positions at each Z height, looking much more
> like something generated by the software in exact same positions at
> each Z level, than some random vibration of the servos (which I'd
> expect to happen differently at each Z height).
>
> Please note that it may be weeks/months before I have to machine again
> these same parts so even if a fix is made, I won't be able to give
> feedback immediately....
>
> Thank you
> EC
>
>
>
> Links:
> ------
> [1]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/messages/14657;_ylc=X3oDMTJyMnVkOHN2BF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRtc2dJZAMxNDY1NwRzZWMDZnRyBHNsawNycGx5BHN0aW1lAzE0OTM1NTM4NDc-?act=reply&messageNum=14657
> [2]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/newtopic;_ylc=X3oDMTJmdDJ2NnFtBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDZnRyBHNsawNudHBjBHN0aW1lAzE0OTM1NTM4NDc-
> [3]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/topics/14657;_ylc=X3oDMTM3NDB0YjRmBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRtc2dJZAMxNDY1NwRzZWMDZnRyBHNsawN2dHBjBHN0aW1lAzE0OTM1NTM4NDcEdHBjSWQDMTQ2NTc-
> [4] https://yho.com/1wwmgg
> [5]
> https://groups.yahoo.com/neo/groups/DynoMotion/info;_ylc=X3oDMTJmbTQ0bnFzBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDdnRsBHNsawN2Z2hwBHN0aW1lAzE0OTM1NTM4NDc-
> [6]
> https://groups.yahoo.com/neo/groups/DynoMotion/members/all;_ylc=X3oDMTJnc3I2dTVrBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDdnRsBHNsawN2bWJycwRzdGltZQMxNDkzNTUzODQ3
> [7]
> https://groups.yahoo.com/neo;_ylc=X3oDMTJlb290bnJtBF9TAzk3NDc2NTkwBGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTQ5MzU1Mzg0Nw--
> [8] https://info.yahoo.com/privacy/us/yahoo/groups/details.html
> [9] https://info.yahoo.com/legal/us/yahoo/utos/terms/

Attachments :

settings-14660.png

Hi,

here is a screenshot of the settings.
In this specific case, that arc is made of 16 facets (if counted them correctly) hence I estimate the deviation (chord error) to be about 1-2 hundredths mm.
Will send the C init file

Thank you
EC

---In DynoMotion@yahoogroups.com, <tk@...> wrote :

Hi EC,

Please post your Tool Setup | Trajectory Planner Settings.

Also your Initialization C File.

How much would you estimate the "facet" path deviates from the
theoretical arc path?

Regards

TK

On 2017-04-30 05:04, ericnc@... [DynoMotion] wrote:
> Hello,
>
> in some circumstances I get faceted arcs even if "arcs to segments" is
> disabled. (Maybe it's not faceted, it's difficult to tell whether they
> are facets or other artifacts that make it look like it was faceted.)
>
> example of a circumstance triggering the problem:
>
> using KmotionCNC 4.34h
>
> units mm
>
> problem arc is:
> starting point X13.3343 Y47.6702
> G3 X0.0 Y49.5 I-13.3343 J-47.6702
> G3 X-13.3343 Y47.6702 I0.0 J-49.5
>
> using these feeds I get the artifacts:
>
> F40.8
> F89.1
> F123.75
> F129.6
>
> using these other feeds I do NOT get the artifacts:
>
> F137.7
> F145.8
> F153.9
> F148.5
>
> Long description of the problem:
>
> It happened first a couple months ago, all the arcs of the workpiece
> were correctly machined as arcs except the arc with the larger radius,
> which was "faceted". I failed to report it on this list but now it
> just happened again with a different workpiece.
> Again, "arcs to segments" is disabled but the arc having the larger
> radius in the workpiece looks like is faceted (it's the arc reported
> above).
>
> I suspect it is a numerical problem affecting certain combinations of
> feed and radius. This time I did repeated testing (I had several
> workpieces to do) and could see that the problem happened with certain
> feeds but didn't happen with slightly faster feeds.
>
> I also considered it could be some instability problem of my badly
> tuned servos, but then I'd expect the artifacts to happen more
> randomly. These happen very regularly instead, and happen exactly in
> the same places at different "Z" heights.
> I was doing "2D 1/2" parts, contouring on the XY plane and repeating
> same contour at different Z levels.
> At you end you get perfect "vertical stripes" i.e the "faceting"
> happened exactly in same positions at each Z height, looking much more
> like something generated by the software in exact same positions at
> each Z level, than some random vibration of the servos (which I'd
> expect to happen differently at each Z height).
>
> Please note that it may be weeks/months before I have to machine again
> these same parts so even if a fix is made, I won't be able to give
> feedback immediately....
>
> Thank you
> EC
>
>
>
> Links:
> ------
> [1]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/messages/14657;_ylc=X3oDMTJyMnVkOHN2BF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRtc2dJZAMxNDY1NwRzZWMDZnRyBHNsawNycGx5BHN0aW1lAzE0OTM1NTM4NDc-?act=reply&messageNum=14657
> [2]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/newtopic;_ylc=X3oDMTJmdDJ2NnFtBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDZnRyBHNsawNudHBjBHN0aW1lAzE0OTM1NTM4NDc-
> [3]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/topics/14657;_ylc=X3oDMTM3NDB0YjRmBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRtc2dJZAMxNDY1NwRzZWMDZnRyBHNsawN2dHBjBHN0aW1lAzE0OTM1NTM4NDcEdHBjSWQDMTQ2NTc-
> [4] https://yho.com/1wwmgg
> [5]
> https://groups.yahoo.com/neo/groups/DynoMotion/info;_ylc=X3oDMTJmbTQ0bnFzBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDdnRsBHNsawN2Z2hwBHN0aW1lAzE0OTM1NTM4NDc-
> [6]
> https://groups.yahoo.com/neo/groups/DynoMotion/members/all;_ylc=X3oDMTJnc3I2dTVrBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDdnRsBHNsawN2bWJycwRzdGltZQMxNDkzNTUzODQ3
> [7]
> https://groups.yahoo.com/neo;_ylc=X3oDMTJlb290bnJtBF9TAzk3NDc2NTkwBGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTQ5MzU1Mzg0Nw--
> [8] https://info.yahoo.com/privacy/us/yahoo/groups/details.html
> [9] https://info.yahoo.com/legal/us/yahoo/utos/terms/

Here is the init file, too:

#include "KMotionDef.h"

#define INCH    (25.4)

#define RESOLUTION_X_MM         (2000)          // counts/mm
#define RESOLUTION_Y_MM         (2000)          // counts/mm
#define RESOLUTION_Z_MM         (4000)          // counts/mm

#define RESOLUTION_X_INCH        (50800)        // counts/inch
#define RESOLUTION_Y_INCH        (50800)        // counts/inch
#define RESOLUTION_Z_INCH       (101600)        // counts/inch

// soft limits

#define XMINUS (-220*RESOLUTION_X_MM)
#define XPLUS   (+240*RESOLUTION_X_MM)
#define YMINUS (-100*RESOLUTION_Y_MM)
#define YPLUS   (+100*RESOLUTION_Y_MM)
#define ZMINUS (-120*RESOLUTION_Z_MM)
#define ZPLUS   (+115*RESOLUTION_Z_MM)

// Defines axis 0, 1, 2 as simple step dir outputs
// enables them
// sets them as an xyz coordinate system for GCode

int main()
{
        // X AXIS PARAMETERS -------------------
        ch0->InputMode=ENCODER_MODE;
        ch0->OutputMode=STEP_DIR_MODE;
//      ch0->OutputMode=CL_STEP_DIR_MODE;
        ch0->Vel=101000;
        ch0->Accel=610000;
        ch0->Jerk=4e+006;
        ch0->P=0.6000;
        ch0->I=0.0250;
        ch0->D=1.2000;
        ch0->FFAccel=0.0;
        ch0->FFVel=0.0;
        ch0->MaxI=5000;
        ch0->MaxErr=1e+006;
        ch0->MaxOutput=5000;
        ch0->DeadBandGain=0;
        ch0->DeadBandRange=3;
        ch0->InputChan0=0;
        ch0->InputChan1=0;
        ch0->OutputChan0=24; // 24 = LVTTL quadrature
        ch0->OutputChan1=0;
        ch0->MasterAxis=-1;
        ch0->LimitSwitchOptions=0x0;
        ch0->SoftLimitNeg=XMINUS;
        ch0->SoftLimitPos=XPLUS;
        ch0->InputGain0=1;
        ch0->InputGain1=1;
        ch0->InputOffset0=0;
        ch0->InputOffset1=0;
        ch0->OutputGain=1;
        ch0->OutputOffset=0;
        ch0->SlaveGain=1;
        ch0->BacklashMode=BACKLASH_LINEAR;
        ch0->BacklashAmount=0;
        ch0->BacklashRate=1000; // counts per second
        ch0->invDistPerCycle=1;
        ch0->Lead=0;
        ch0->MaxFollowingError=1000000000;
        ch0->StepperAmplitude=20;

        ch0->iir[0].B0=1;
        ch0->iir[0].B1=0;
        ch0->iir[0].B2=0;
        ch0->iir[0].A1=0;
        ch0->iir[0].A2=0;

        ch0->iir[1].B0=1;
        ch0->iir[1].B1=0;
        ch0->iir[1].B2=0;
        ch0->iir[1].A1=0;
        ch0->iir[1].A2=0;

        ch0->iir[2].B0=0.00454;
        ch0->iir[2].B1=0.00908;
        ch0->iir[2].B2=0.00454;
        ch0->iir[2].A1=1.80217;
        ch0->iir[2].A2=-0.820331;

    // Y AXIS PARAMETERS -------------------
        ch1->InputMode=NO_INPUT_MODE;
        ch1->OutputMode=STEP_DIR_MODE;
        ch1->Vel=40000;
        ch1->Accel=400000;
        ch1->Jerk=4e+006;
        ch1->P=0;
        ch1->I=0.01;
        ch1->D=0;
        ch1->FFAccel=0;
        ch1->FFVel=0;
        ch1->MaxI=200;
        ch1->MaxErr=1e+006;
        ch1->MaxOutput=200;
        ch1->DeadBandGain=1;
        ch1->DeadBandRange=0;
        ch1->InputChan0=1;
        ch1->InputChan1=0;
        ch1->OutputChan0=25; // 25 = LVTTL quadrature
        ch1->OutputChan1=0;
        ch1->MasterAxis=-1;
        ch1->LimitSwitchOptions=0x0;
        ch1->SoftLimitNeg=YMINUS;
        ch1->SoftLimitPos=YPLUS;
        ch1->InputGain0=1;
        ch1->InputGain1=1;
        ch1->InputOffset0=0;
        ch1->InputOffset1=0;
        ch1->OutputGain=(-1.0);
        ch1->OutputOffset=0;
        ch1->SlaveGain=1;
        ch1->BacklashMode=BACKLASH_LINEAR;
        ch1->BacklashAmount=0;
        ch1->BacklashRate=1000; // counts per second
        ch1->invDistPerCycle=1;
        ch1->Lead=0;
        ch1->MaxFollowingError=1000000000;
        ch1->StepperAmplitude=20;

        ch1->iir[0].B0=1;
        ch1->iir[0].B1=0;
        ch1->iir[0].B2=0;
        ch1->iir[0].A1=0;
        ch1->iir[0].A2=0;

        ch1->iir[1].B0=1;
        ch1->iir[1].B1=0;
        ch1->iir[1].B2=0;
        ch1->iir[1].A1=0;
        ch1->iir[1].A2=0;

        ch1->iir[2].B0=0.000769;
        ch1->iir[2].B1=0.001538;
        ch1->iir[2].B2=0.000769;
        ch1->iir[2].A1=1.92081;
        ch1->iir[2].A2=-0.923885;

        // Z AXIS PARAMETERS -------------------
        ch2->InputMode=NO_INPUT_MODE;
        ch2->OutputMode=STEP_DIR_MODE;
        ch2->Vel=20000;
        ch2->Accel=400000;
        ch2->Jerk=4e+006;
        ch2->P=0;
        ch2->I=0.01;
        ch2->D=0;
        ch2->FFAccel=0;
        ch2->FFVel=0;
        ch2->MaxI=200;
        ch2->MaxErr=1e+006;
        ch2->MaxOutput=200;
        ch2->DeadBandGain=1;
        ch2->DeadBandRange=0;
        ch2->InputChan0=2;
        ch2->InputChan1=0;
        ch2->OutputChan0=26; // 26 = LVTTL quadrature
        ch2->OutputChan1=0;
        ch2->MasterAxis=-1;
        ch2->LimitSwitchOptions=0x0;
        ch2->SoftLimitNeg=ZMINUS;
        ch2->SoftLimitPos=ZPLUS;
        ch2->InputGain0=1;
        ch2->InputGain1=1;
        ch2->InputOffset0=0;
        ch2->InputOffset1=0;
        ch2->OutputGain=(-1);
        ch2->OutputOffset=0;
        ch2->SlaveGain=1;
        ch2->BacklashMode=BACKLASH_LINEAR;
        ch2->BacklashAmount=50; //counts
        ch2->BacklashRate=1000; // counts per second
        ch2->invDistPerCycle=1;
        ch2->Lead=0;
        ch2->MaxFollowingError=1000000000;
        ch2->StepperAmplitude=20;

        ch2->iir[0].B0=1;
        ch2->iir[0].B1=0;
        ch2->iir[0].B2=0;
        ch2->iir[0].A1=0;
        ch2->iir[0].A2=0;

        ch2->iir[1].B0=1;
        ch2->iir[1].B1=0;
        ch2->iir[1].B2=0;
        ch2->iir[1].A1=0;
        ch2->iir[1].A2=0;

        ch2->iir[2].B0=0.000769;
        ch2->iir[2].B1=0.001538;
        ch2->iir[2].B2=0.000769;
        ch2->iir[2].A1=1.92081;
        ch2->iir[2].A2=-0.923885;

        EnableAxisDest(0,+000.00*RESOLUTION_X_MM); Zero(0); // X
        EnableAxisDest(1,+000.00*RESOLUTION_Y_MM); // Y
        EnableAxisDest(2,+090.00*RESOLUTION_Z_MM); // Z

        DefineCoordSystem(0,1,2,-1);

    return 0;
}

---In DynoMotion@yahoogroups.com, <tk@...> wrote :

Hi EC,

Please post your Tool Setup | Trajectory Planner Settings.

Also your Initialization C File.

How much would you estimate the "facet" path deviates from the
theoretical arc path?

Regards

TK

On 2017-04-30 05:04, ericnc@... [DynoMotion] wrote:
> Hello,
>
> in some circumstances I get faceted arcs even if "arcs to segments" is
> disabled. (Maybe it's not faceted, it's difficult to tell whether they
> are facets or other artifacts that make it look like it was faceted.)
>
> example of a circumstance triggering the problem:
>
> using KmotionCNC 4.34h
>
> units mm
>
> problem arc is:
> starting point X13.3343 Y47.6702
> G3 X0.0 Y49.5 I-13.3343 J-47.6702
> G3 X-13.3343 Y47.6702 I0.0 J-49.5
>
> using these feeds I get the artifacts:
>
> F40.8
> F89.1
> F123.75
> F129.6
>
> using these other feeds I do NOT get the artifacts:
>
> F137.7
> F145.8
> F153.9
> F148.5
>
> Long description of the problem:
>
> It happened first a couple months ago, all the arcs of the workpiece
> were correctly machined as arcs except the arc with the larger radius,
> which was "faceted". I failed to report it on this list but now it
> just happened again with a different workpiece.
> Again, "arcs to segments" is disabled but the arc having the larger
> radius in the workpiece looks like is faceted (it's the arc reported
> above).
>
> I suspect it is a numerical problem affecting certain combinations of
> feed and radius. This time I did repeated testing (I had several
> workpieces to do) and could see that the problem happened with certain
> feeds but didn't happen with slightly faster feeds.
>
> I also considered it could be some instability problem of my badly
> tuned servos, but then I'd expect the artifacts to happen more
> randomly. These happen very regularly instead, and happen exactly in
> the same places at different "Z" heights.
> I was doing "2D 1/2" parts, contouring on the XY plane and repeating
> same contour at different Z levels.
> At you end you get perfect "vertical stripes" i.e the "faceting"
> happened exactly in same positions at each Z height, looking much more
> like something generated by the software in exact same positions at
> each Z level, than some random vibration of the servos (which I'd
> expect to happen differently at each Z height).
>
> Please note that it may be weeks/months before I have to machine again
> these same parts so even if a fix is made, I won't be able to give
> feedback immediately....
>
> Thank you
> EC
>
>
>
> Links:
> ------
> [1]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/messages/14657;_ylc=X3oDMTJyMnVkOHN2BF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRtc2dJZAMxNDY1NwRzZWMDZnRyBHNsawNycGx5BHN0aW1lAzE0OTM1NTM4NDc-?act=reply&messageNum=14657
> [2]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/newtopic;_ylc=X3oDMTJmdDJ2NnFtBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDZnRyBHNsawNudHBjBHN0aW1lAzE0OTM1NTM4NDc-
> [3]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/topics/14657;_ylc=X3oDMTM3NDB0YjRmBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRtc2dJZAMxNDY1NwRzZWMDZnRyBHNsawN2dHBjBHN0aW1lAzE0OTM1NTM4NDcEdHBjSWQDMTQ2NTc-
> [4] https://yho.com/1wwmgg
> [5]
> https://groups.yahoo.com/neo/groups/DynoMotion/info;_ylc=X3oDMTJmbTQ0bnFzBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDdnRsBHNsawN2Z2hwBHN0aW1lAzE0OTM1NTM4NDc-
> [6]
> https://groups.yahoo.com/neo/groups/DynoMotion/members/all;_ylc=X3oDMTJnc3I2dTVrBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDdnRsBHNsawN2bWJycwRzdGltZQMxNDkzNTUzODQ3
> [7]
> https://groups.yahoo.com/neo;_ylc=X3oDMTJlb290bnJtBF9TAzk3NDc2NTkwBGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTQ5MzU1Mzg0Nw--
> [8] https://info.yahoo.com/privacy/us/yahoo/groups/details.html
> [9] https://info.yahoo.com/legal/us/yahoo/utos/terms/

Hi EC,

Basically the facets will be created when the chord errors are less than your allowed Collinear Tolerance. Try reducing your Collinear Tolerance to 0.0002in (5um). I'm surprised you can see ~10um deviations. Your system must be very accurate. Could you post a photo?

Please see this article added to the wiki.

http://www.dynomotion.com/wiki/index.php?title=ArcFacetingColinearTol

Regards

On 4/30/2017 4:15 PM, ericnc@... [DynoMotion] wrote:

Hi,

here is a screenshot of the settings.
In this specific case, that arc is made of 16 facets (if counted them correctly) hence I estimate the deviation (chord error) to be about 1-2 hundredths mm.
Will send the C init file

Thank you
EC

---In DynoMotion@yahoogroups.com, <tk@...> wrote :

Hi EC,

Please post your Tool Setup | Trajectory Planner Settings.

Also your Initialization C File.

How much would you estimate the "facet" path deviates from the
theoretical arc path?

Regards

TK

On 2017-04-30 05:04, ericnc@... [DynoMotion] wrote:
> Hello,
>
> in some circumstances I get faceted arcs even if "arcs to segments" is
> disabled. (Maybe it's not faceted, it's difficult to tell whether they
> are facets or other artifacts that make it look like it was faceted.)
>
> example of a circumstance triggering the problem:
>
> using KmotionCNC 4.34h
>
> units mm
>
> problem arc is:
> starting point X13.3343 Y47.6702
> G3 X0.0 Y49.5 I-13.3343 J-47.6702
> G3 X-13.3343 Y47.6702 I0.0 J-49.5
>
> using these feeds I get the artifacts:
>
> F40.8
> F89.1
> F123.75
> F129.6
>
> using these other feeds I do NOT get the artifacts:
>
> F137.7
> F145.8
> F153.9
> F148.5
>
> Long description of the problem:
>
> It happened first a couple months ago, all the arcs of the workpiece
> were correctly machined as arcs except the arc with the larger radius,
> which was "faceted". I failed to report it on this list but now it
> just happened again with a different workpiece.
> Again, "arcs to segments" is disabled but the arc having the larger
> radius in the workpiece looks like is faceted (it's the arc reported
> above).
>
> I suspect it is a numerical problem affecting certain combinations of
> feed and radius. This time I did repeated testing (I had several
> workpieces to do) and could see that the problem happened with certain
> feeds but didn't happen with slightly faster feeds.
>
> I also considered it could be some instability problem of my badly
> tuned servos, but then I'd expect the artifacts to happen more
> randomly. These happen very regularly instead, and happen exactly in
> the same places at different "Z" heights.
> I was doing "2D 1/2" parts, contouring on the XY plane and repeating
> same contour at different Z levels.
> At you end you get perfect "vertical stripes" i.e the "faceting"
> happened exactly in same positions at each Z height, looking much more
> like something generated by the software in exact same positions at
> each Z level, than some random vibration of the servos (which I'd
> expect to happen differently at each Z height).
>
> Please note that it may be weeks/months before I have to machine again
> these same parts so even if a fix is made, I won't be able to give
> feedback immediately....
>
> Thank you
> EC
>
>
>
> Links:
> ------
> [1]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/messages/14657;_ylc=X3oDMTJyMnVkOHN2BF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRtc2dJZAMxNDY1NwRzZWMDZnRyBHNsawNycGx5BHN0aW1lAzE0OTM1NTM4NDc-?act=reply&messageNum=14657
> [2]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/newtopic;_ylc=X3oDMTJmdDJ2NnFtBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDZnRyBHNsawNudHBjBHN0aW1lAzE0OTM1NTM4NDc-
> [3]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/topics/14657;_ylc=X3oDMTM3NDB0YjRmBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRtc2dJZAMxNDY1NwRzZWMDZnRyBHNsawN2dHBjBHN0aW1lAzE0OTM1NTM4NDcEdHBjSWQDMTQ2NTc-
> [4] https://yho.com/1wwmgg
> [5]
> https://groups.yahoo.com/neo/groups/DynoMotion/info;_ylc=X3oDMTJmbTQ0bnFzBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDdnRsBHNsawN2Z2hwBHN0aW1lAzE0OTM1NTM4NDc-
> [6]
> https://groups.yahoo.com/neo/groups/DynoMotion/members/all;_ylc=X3oDMTJnc3I2dTVrBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDdnRsBHNsawN2bWJycwRzdGltZQMxNDkzNTUzODQ3
> [7]
> https://groups.yahoo.com/neo;_ylc=X3oDMTJlb290bnJtBF9TAzk3NDc2NTkwBGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTQ5MzU1Mzg0Nw--
> [8] https://info.yahoo.com/privacy/us/yahoo/groups/details.html
> [9] https://info.yahoo.com/legal/us/yahoo/utos/terms/

Thank you Tom,

I've read the article you added to the wiki about my arc... so if I understand correctly, sometimes the trajectory planner decides to facet the arcs even if "Arcs to Segments" is turned off!
And this happens when the execute time is more than a certain value.
So as in my case the time was approx that value, small changes in the Feed value caused that behavior to be triggered or not.

Will try to get you a picture. It's not easy as it seems, the facets show depending on the angle of the light... something similar to the "Zebra Stripes" sometimes used in CAD for checking surfaces, if you know what I'm talking about... very visible to the naked eye but not sure I'll be able to catch them on the camera

Thank you
EC

---In DynoMotion@yahoogroups.com, <tk@...> wrote :

Hi EC,

Please see this article added to the wiki.

http://www.dynomotion.com/wiki/index.php?title=ArcFacetingColinearTol

Regards

On 4/30/2017 4:15 PM, ericnc@... [DynoMotion] wrote:

Hi,

here is a screenshot of the settings.
In this specific case, that arc is made of 16 facets (if counted them correctly) hence I estimate the deviation (chord error) to be about 1-2 hundredths mm.
Will send the C init file

Thank you
EC

---In DynoMotion@yahoogroups.com, <tk@...> wrote :

Hi EC,

Please post your Tool Setup | Trajectory Planner Settings.

Also your Initialization C File.

How much would you estimate the "facet" path deviates from the
theoretical arc path?

Regards

TK

On 2017-04-30 05:04, ericnc@... [DynoMotion] wrote:
> Hello,
>
> in some circumstances I get faceted arcs even if "arcs to segments" is
> disabled. (Maybe it's not faceted, it's difficult to tell whether they
> are facets or other artifacts that make it look like it was faceted.)
>
> example of a circumstance triggering the problem:
>
> using KmotionCNC 4.34h
>
> units mm
>
> problem arc is:
> starting point X13.3343 Y47.6702
> G3 X0.0 Y49.5 I-13.3343 J-47.6702
> G3 X-13.3343 Y47.6702 I0.0 J-49.5
>
> using these feeds I get the artifacts:
>
> F40.8
> F89.1
> F123.75
> F129.6
>
> using these other feeds I do NOT get the artifacts:
>
> F137.7
> F145.8
> F153.9
> F148.5
>
> Long description of the problem:
>
> It happened first a couple months ago, all the arcs of the workpiece
> were correctly machined as arcs except the arc with the larger radius,
> which was "faceted". I failed to report it on this list but now it
> just happened again with a different workpiece.
> Again, "arcs to segments" is disabled but the arc having the larger
> radius in the workpiece looks like is faceted (it's the arc reported
> above).
>
> I suspect it is a numerical problem affecting certain combinations of
> feed and radius. This time I did repeated testing (I had several
> workpieces to do) and could see that the problem happened with certain
> feeds but didn't happen with slightly faster feeds.
>
> I also considered it could be some instability problem of my badly
> tuned servos, but then I'd expect the artifacts to happen more
> randomly. These happen very regularly instead, and happen exactly in
> the same places at different "Z" heights.
> I was doing "2D 1/2" parts, contouring on the XY plane and repeating
> same contour at different Z levels.
> At you end you get perfect "vertical stripes" i.e the "faceting"
> happened exactly in same positions at each Z height, looking much more
> like something generated by the software in exact same positions at
> each Z level, than some random vibration of the servos (which I'd
> expect to happen differently at each Z height).
>
> Please note that it may be weeks/months before I have to machine again
> these same parts so even if a fix is made, I won't be able to give
> feedback immediately....
>
> Thank you
> EC
>
>
>
> Links:
> ------
> [1]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/messages/14657;_ylc=X3oDMTJyMnVkOHN2BF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRtc2dJZAMxNDY1NwRzZWMDZnRyBHNsawNycGx5BHN0aW1lAzE0OTM1NTM4NDc-?act=reply&messageNum=14657
> [2]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/newtopic;_ylc=X3oDMTJmdDJ2NnFtBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDZnRyBHNsawNudHBjBHN0aW1lAzE0OTM1NTM4NDc-
> [3]
> https://groups.yahoo.com/neo/groups/DynoMotion/conversations/topics/14657;_ylc=X3oDMTM3NDB0YjRmBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRtc2dJZAMxNDY1NwRzZWMDZnRyBHNsawN2dHBjBHN0aW1lAzE0OTM1NTM4NDcEdHBjSWQDMTQ2NTc-
> [4] https://yho.com/1wwmgg
> [5]
> https://groups.yahoo.com/neo/groups/DynoMotion/info;_ylc=X3oDMTJmbTQ0bnFzBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDdnRsBHNsawN2Z2hwBHN0aW1lAzE0OTM1NTM4NDc-
> [6]
> https://groups.yahoo.com/neo/groups/DynoMotion/members/all;_ylc=X3oDMTJnc3I2dTVrBF9TAzk3MzU5NzE0BGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDdnRsBHNsawN2bWJycwRzdGltZQMxNDkzNTUzODQ3
> [7]
> https://groups.yahoo.com/neo;_ylc=X3oDMTJlb290bnJtBF9TAzk3NDc2NTkwBGdycElkAzE1ODU4MDAxBGdycHNwSWQDMTcwNjU1NDIwNQRzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTQ5MzU1Mzg0Nw--
> [8] https://info.yahoo.com/privacy/us/yahoo/groups/details.html
> [9] https://info.yahoo.com/legal/us/yahoo/utos/terms/

Attachments :

facets-01-14666.jpg

Here is a photo.
There are two workpieces in the picture, one machined with F123.75 and the other one with
F145.8 (if I remember correctly).

Thank you
EC

---In DynoMotion@yahoogroups.com, <tk@...> wrote :

Hi EC,

Please see this article added to the wiki.

http://www.dynomotion.com/wiki/index.php?title=ArcFacetingColinearTol

Regards

On 4/30/2017 4:15 PM, ericnc@... [DynoMotion] wrote:

Hi,

here is a screenshot of the settings.
In this specific case, that arc is made of 16 facets (if counted them correctly) hence I estimate the deviation (chord error) to be about 1-2 hundredths mm.
Will send the C init file

Thank you
EC

---In DynoMotion@yahoogroups.com, <tk@...> wrote :

Hi EC,

Please post your Tool Setup | Trajectory Planner Settings.

Also your Initialization C File.

How much would you estimate the "facet" path deviates from the
theoretical arc path?

Regards

TK

On 2017-04-30 05:04, ericnc@... [DynoMotion] wrote:
> Hello,
>
> in some circumstances I get faceted arcs even if "arcs to segments" is
> disabled. (Maybe it's not faceted, it's difficult to tell whether they
> are facets or other artifacts that make it look like it was faceted.)
>
> example of a circumstance triggering the problem:
>
> using KmotionCNC 4.34h
>
> units mm
>
> problem arc is:
> starting point X13.3343 Y47.6702
> G3 X0.0 Y49.5 I-13.3343 J-47.6702
> G3 X-13.3343 Y47.6702 I0.0 J-49.5
>
> using these feeds I get the artifacts:
>
> F40.8
> F89.1
> F123.75
> F129.6
>
> using these other feeds I do NOT get the artifacts:
>
> F137.7
> F145.8
> F153.9
> F148.5
>
> Long description of the problem:
>
> It happened first a couple months ago, all the arcs of the workpiece
> were correctly machined as arcs except the arc with the larger radius,
> which was "faceted". I failed to report it on this list but now it
> just happened again with a different workpiece.
> Again, "arcs to segments" is disabled but the arc having the larger
> radius in the workpiece looks like is faceted (it's the arc reported
> above).
>
> I suspect it is a numerical problem affecting certain combinations of
> feed and radius. This time I did repeated testing (I had several
> workpieces to do) and could see that the problem happened with certain
> feeds but didn't happen with slightly faster feeds.
>
> I also considered it could be some instability problem of my badly
> tuned servos, but then I'd expect the artifacts to happen more
> randomly. These happen very regularly instead, and happen exactly in
> the same places at different "Z" heights.
> I was doing "2D 1/2" parts, contouring on the XY plane and repeating
> same contour at different Z levels.
> At you end you get perfect "vertical stripes" i.e the "faceting"
> happened exactly in same positions at each Z height, looking much more
> like something generated by the software in exact same positions at
> each Z level, than some random vibration of the servos (which I'd
> expect to happen differently at each Z height).
>
> Please note that it may be weeks/months before I have to machine again
> these same parts so even if a fix is made, I won't be able to give
> feedback immediately....
>
> Thank you
> EC

Hi EC,

Interesting. Nice photo.

Thanks

On 5/2/2017 12:51 PM, ericnc@... [DynoMotion] wrote:

Here is a photo.
There are two workpieces in the picture, one machined with F123.75 and the other one with
F145.8 (if I remember correctly).

Thank you
EC

---In DynoMotion@yahoogroups.com, <tk@...> wrote :

Hi EC,

Basically the facets will be created when the chord errors are less than your allowed Collinear Tolerance. Try reducing your Collinear Tolerance to 0.0002in (5um). I'm surprised you can see ~10um deviations. Your system must be very accurate. Could you post a photo?

Please see this article added to the wiki.

http://www.dynomotion.com/wiki/index.php?title=ArcFacetingColinearTol

Regards

TK

On 4/30/2017 4:15 PM, ericnc@... [DynoMotion] wrote:

Hi,

here is a screenshot of the settings.
In this specific case, that arc is made of 16 facets (if counted them correctly) hence I estimate the deviation (chord error) to be about 1-2 hundredths mm.
Will send the C init file

Thank you
EC

---In DynoMotion@yahoogroups.com, <tk@...> wrote :

Hi EC,

Please post your Tool Setup | Trajectory Planner Settings.

Also your Initialization C File.

How much would you estimate the "facet" path deviates from the
theoretical arc path?

Regards

TK

On 2017-04-30 05:04, ericnc@... [DynoMotion] wrote:
> Hello,
>
> in some circumstances I get faceted arcs even if "arcs to segments" is
> disabled. (Maybe it's not faceted, it's difficult to tell whether they
> are facets or other artifacts that make it look like it was faceted.)
>
> example of a circumstance triggering the problem:
>
> using KmotionCNC 4.34h
>
> units mm
>
> problem arc is:
> starting point X13.3343 Y47.6702
> G3 X0.0 Y49.5 I-13.3343 J-47.6702
> G3 X-13.3343 Y47.6702 I0.0 J-49.5
>
> using these feeds I get the artifacts:
>
> F40.8
> F89.1
> F123.75
> F129.6
>
> using these other feeds I do NOT get the artifacts:
>
> F137.7
> F145.8
> F153.9
> F148.5
>
> Long description of the problem:
>
> It happened first a couple months ago, all the arcs of the workpiece
> were correctly machined as arcs except the arc with the larger radius,
> which was "faceted". I failed to report it on this list but now it
> just happened again with a different workpiece.
> Again, "arcs to segments" is disabled but the arc having the larger
> radius in the workpiece looks like is faceted (it's the arc reported
> above).
>
> I suspect it is a numerical problem affecting certain combinations of
> feed and radius. This time I did repeated testing (I had several
> workpieces to do) and could see that the problem happened with certain
> feeds but didn't happen with slightly faster feeds.
>
> I also considered it could be some instability problem of my badly
> tuned servos, but then I'd expect the artifacts to happen more
> randomly. These happen very regularly instead, and happen exactly in
> the same places at different "Z" heights.
> I was doing "2D 1/2" parts, contouring on the XY plane and repeating
> same contour at different Z levels.
> At you end you get perfect "vertical stripes" i.e the "faceting"
> happened exactly in same positions at each Z height, looking much more
> like something generated by the software in exact same positions at
> each Z level, than some random vibration of the servos (which I'd
> expect to happen differently at each Z height).
>
> Please note that it may be weeks/months before I have to machine again
> these same parts so even if a fix is made, I won't be able to give
> feedback immediately....
>
> Thank you
> EC

Group: DynoMotion	Message: 14657	From: ericncn	Date: 4/30/2017
Subject: arcs: bug? numerical problem? servo instability?

Group: DynoMotion	Message: 14659	From: TKSOFT	Date: 4/30/2017
Subject: Re: arcs: bug? numerical problem? servo instability?

Group: DynoMotion	Message: 14660	From: ericncn	Date: 4/30/2017
Subject: Re: arcs: bug? numerical problem? servo instability?

Group: DynoMotion	Message: 14661	From: ericncn	Date: 4/30/2017
Subject: Re: arcs: bug? numerical problem? servo instability?

Group: DynoMotion	Message: 14662	From: Tom Kerekes	Date: 5/1/2017
Subject: Re: arcs: bug? numerical problem? servo instability? [1 Attachment]

Group: DynoMotion	Message: 14663	From: ericncn	Date: 5/2/2017
Subject: Re: arcs: bug? numerical problem? servo instability? [1 Attachment]

Group: DynoMotion	Message: 14666	From: ericncn	Date: 5/2/2017
Subject: Re: arcs: bug? numerical problem? servo instability? [1 Attachment]

Group: DynoMotion	Message: 14668	From: Tom Kerekes	Date: 5/2/2017
Subject: Re: arcs: bug? numerical problem? servo instability? [1 Attachment]