Backlash compensation

RAyWB

Hi,
tried backlash compensation on threaded rod drive machine fired by due and have a question:
when getting to the turnover point where direction changes machine seems to stop shortly.
clearly visible when printing circles.
if i set backlash to 0 it has normal behavior. Is there a possibility to speed up ?

stopping position is visible in printed part :-(

Repetier

You see backlash logic in motion.cpp line 206-242.

As you see all it does is adding a second move on direction change. That also needs 2 free moves to place so it reduces buffer space for travel distance. So all I can think of is that your max. buffer size should be increased to at least 32 to accomodate for extra moves without penalty for path planner, which is especially important in circles which I guess is what you tested.

RAyWB

buffer size is 40 , also tried 80.
i do the test with circles , thats right, but on turnover point machine nearly stops.
if i set backlash values to 0 it runs absolutely smooth.
as soon as i put a value (in my case i need 0.005mm to 0.009) it slows down extremely just at turnover point.
machine step size is 0.00166 mm , so i need 3 to 5 steps.

is there a change of feedrate in the added moves?
any idea?

Repetier

No feedrate stays unchanged.

Does it also happen in a simple case with 2 lines? Then you could add

#define DEBUG_QUEUE_MOVEand enable echo before running. It will out to log the moves and speeds it computes for this. You might need 1-2 pre moves to fill buffer.

RAyWB

seems to happen illogical
using cambam gcode with G3 circles everything is ok also circles by G1 lines.

here??s a snippet from gcode where that slow down happens(extruder is commented, feedrate set to 2400mm/min) :

Gcode is generated by slic3r , also Cura or S3D makes not a difference

any value in backlash slows down in turnover point, set values to 0 it runs smooth.
may be you can check it out , its really strange

G1 X291.517 Y113.106 F2400;E6.02030 F3600.000
G1 X291.795 Y114.315 ;E6.08249
G1 X291.994 Y115.535 ;E6.14451
G1 X292.113 Y116.763 ;E6.20640
G1 X292.153 Y118.000 ;E6.26846
G1 X292.113 Y119.237 ;E6.33051
G1 X291.994 Y120.465 ;E6.39240
G1 X291.795 Y121.685 ;E6.45443
G1 X291.517 Y122.894 ;E6.51661
G1 X291.165 Y124.072 ;E6.57830
G1 X290.735 Y125.233 ;E6.64039
G1 X290.228 Y126.367 ;E6.70270
G1 X289.657 Y127.452 ;E6.76420
G1 X289.011 Y128.510 ;E6.82635
G1 X288.299 Y129.520 ;E6.88834
G1 X287.524 Y130.483 ;E6.95032
G1 X286.681 Y131.401 ;E7.01285
G1 X286.401 Y131.681 ;E7.03272
G1 X285.479 Y132.528 ;E7.09548
G1 X284.528 Y133.294 ;E7.15677
G1 X283.510 Y134.011 ;E7.21922
G1 X282.452 Y134.657 ;E7.28137
G1 X281.367 Y135.228 ;E7.34286
G1 X280.233 Y135.735 ;E7.40518
G1 X279.072 Y136.165 ;E7.46726
G1 X277.894 Y136.518 ;E7.52896
G1 X276.685 Y136.795 ;E7.59114
G1 X275.465 Y136.994 ;E7.65317
G1 X274.237 Y137.113 ;E7.71506
G1 X273.000 Y137.153 ;E7.77711
G1 X271.763 Y137.113 ;E7.83917
G1 X270.535 Y136.994 ;E7.90106
G1 X269.315 Y136.795 ;E7.96308
G1 X268.106 Y136.518 ;E8.02526
G1 X266.928 Y136.165 ;E8.08696
G1 X265.767 Y135.735 ;E8.14905
G1 X264.633 Y135.228 ;E8.21136
G1 X263.548 Y134.657 ;E8.27286
G1 X262.490 Y134.011 ;E8.33501
G1 X261.472 Y133.294 ;E8.39745
G1 X260.521 Y132.528 ;E8.45875
G1 X259.599 Y131.681 ;E8.52150
G1 X259.319 Y131.401 ;E8.54138
G1 X258.476 Y130.483 ;E8.60390
G1 X257.701 Y129.520 ;E8.66588
G1 X256.989 Y128.510 ;E8.72787
G1 X256.343 Y127.452 ;E8.79002
G1 X255.772 Y126.367 ;E8.85152
G1 X255.265 Y125.233 ;E8.91383
G1 X254.835 Y124.072 ;E8.97592
G1 X254.482 Y122.894 ;E9.03761
G1 X254.205 Y121.685 ;E9.09980
G1 X254.006 Y120.465 ;E9.16182
G1 X253.887 Y119.237 ;E9.22371
G1 X253.847 Y118.000 ;E9.28576
G1 X253.887 Y116.763 ;E9.34782
G1 X254.006 Y115.535 ;E9.40971
G1 X254.205 Y114.315 ;E9.47173
G1 X254.482 Y113.106 ;E9.53392
G1 X254.835 Y111.928 ;E9.59561
G1 X255.265 Y110.767 ;E9.65770
G1 X255.772 Y109.633 ;E9.72001
G1 X256.343 Y108.548 ;E9.78151
G1 X256.989 Y107.490 ;E9.84366
G1 X257.701 Y106.480 ;E9.90565
G1 X258.476 Y105.517 ;E9.96763
G1 X259.319 Y104.599 ;E10.03015
G1 X259.599 Y104.319 ;E10.05003
G1 X260.521 Y103.472 ;E10.11278
G1 X261.472 Y102.706 ;E10.17408
G1 X262.490 Y101.989 ;E10.23652
G1 X263.548 Y101.343 ;E10.29868
G1 X264.633 Y100.772 ;E10.36017
G1 X265.767 Y100.265 ;E10.42248
G1 X266.928 Y99.835 ;E10.48457
G1 X268.106 Y99.482 ;E10.54627
G1 X269.315 Y99.205 ;E10.60845
G1 X270.535 Y99.006 ;E10.67044
G1 X271.765 Y98.887 ;E10.73243
G1 X273.000 Y98.847 ;E10.79444
G1 X273.407 Y98.859 ;E10.81483
G1 X274.235 Y98.887 ;E10.85640
G1 X275.465 Y99.006 ;E10.91840
G1 X276.685 Y99.205 ;E10.98039
G1 X277.890 Y99.482 ;E11.04238
G1 X279.074 Y99.836 ;E11.10436
G1 X280.238 Y100.267 ;E11.16663
G1 X280.609 Y100.428 ;E11.18689
G1 X281.359 Y100.768 ;E11.22820
G1 X282.455 Y101.344 ;E11.29033
G1 X283.517 Y101.993 ;E11.35273
G1 X283.850 Y102.220 ;E11.37292
G1 X284.517 Y102.698 ;E11.41410
G1 X285.483 Y103.476 ;E11.47629
G1 X286.401 Y104.319 ;E11.53881
G1 X286.681 Y104.599 ;E11.55869
G1 X287.528 Y105.521 ;E11.62145
G1 X288.048 Y106.155 ;E11.66258
G1 X288.294 Y106.472 ;E11.68275
G1 X289.011 Y107.490 ;E11.74519
G1 X289.657 Y108.548 ;E11.80734
G1 X290.045 Y109.273 ;E11.84860
G1 X290.228 Y109.633 ;E11.86884
G1 X290.735 Y110.767 ;E11.93115
G1 X291.165 Y111.928 ;E11.99324
G1 X291.387 Y112.660 ;E12.03162
;G1 X291.806 Y112.598 F6000.000
G1 X291.923 Y113.001 F2400;E12.05265 F3600.000
G1 X292.207 Y114.234 ;E12.11610
G1 X292.410 Y115.481 ;E12.17947
G1 X292.532 Y116.737 ;E12.24276
G1 X292.572 Y118.000 ;E12.30614
G1 X292.532 Y119.263 ;E12.36953
G1 X292.410 Y120.519 ;E12.43282
G1 X292.207 Y121.766 ;E12.49618
G1 X291.923 Y122.999 ;E12.55964
G1 X291.562 Y124.206 ;E12.62282
G1 X291.123 Y125.391 ;E12.68622
G1 X290.606 Y126.548 ;E12.74975
G1 X290.021 Y127.661 ;E12.81281
G1 X289.361 Y128.740 ;E12.87625
G1 X288.634 Y129.772 ;E12.93959
G1 X287.842 Y130.756 ;E13.00293
G1 X286.984 Y131.691 ;E13.06659
G1 X286.691 Y131.984 ;E13.08736
G1 X285.754 Y132.844 ;E13.15115
G1 X284.777 Y133.631 ;E13.21409
G1 X283.740 Y134.361 ;E13.27770
G1 X282.661 Y135.021 ;E13.34114
G1 X281.548 Y135.606 ;E13.40420
G1 X280.391 Y136.123 ;E13.46773
G1 X279.206 Y136.562 ;E13.53113
G1 X277.999 Y136.923 ;E13.59431
G1 X276.766 Y137.207 ;E13.65777
G1 X275.519 Y137.410 ;E13.72113
G1 X274.263 Y137.532 ;E13.78442
G1 X273.000 Y137.572 ;E13.84781
G1 X271.737 Y137.532 ;E13.91119
G1 X270.481 Y137.410 ;E13.97448
G1 X269.234 Y137.207 ;E14.03785
G1 X268.001 Y136.923 ;E14.10131
G1 X266.794 Y136.562 ;E14.16448
G1 X265.609 Y136.123 ;E14.22788
G1 X264.452 Y135.606 ;E14.29142
G1 X263.339 Y135.021 ;E14.35448
G1 X262.260 Y134.361 ;E14.41791
G1 X261.223 Y133.631 ;E14.48152
G1 X260.246 Y132.844 ;E14.54446
G1 X259.309 Y131.984 ;E14.60825
G1 X259.016 Y131.691 ;E14.62903
G1 X258.158 Y130.756 ;E14.69268
G1 X257.366 Y129.772 ;E14.75602
G1 X256.639 Y128.740 ;E14.81936
G1 X255.979 Y127.661 ;E14.88280
G1 X255.394 Y126.548 ;E14.94586
G1 X254.877 Y125.391 ;E15.00939
G1 X254.438 Y124.206 ;E15.07280
G1 X254.077 Y122.999 ;E15.13597
G1 X253.793 Y121.766 ;E15.19943
G1 X253.590 Y120.519 ;E15.26280
G1 X253.468 Y119.263 ;E15.32609
G1 X253.428 Y118.000 ;E15.38947
G1 X253.468 Y116.737 ;E15.45285
G1 X253.590 Y115.481 ;E15.51614
G1 X253.793 Y114.234 ;E15.57951
G1 X254.077 Y113.001 ;E15.64297
G1 X254.438 Y111.794 ;E15.70614
G1 X254.877 Y110.609 ;E15.76955
G1 X255.394 Y109.452 ;E15.83308
G1 X255.979 Y108.339 ;E15.89614
G1 X256.639 Y107.260 ;E15.95958
G1 X257.366 Y106.228 ;E16.02292
G1 X258.158 Y105.244 ;E16.08626
G1 X259.016 Y104.309 ;E16.14991
G1 X259.309 Y104.016 ;E16.17069
G1 X260.246 Y103.156 ;E16.23448
G1 X261.223 Y102.369 ;E16.29742
G1 X262.260 Y101.639 ;E16.36103
G1 X263.339 Y100.979 ;E16.42447
G1 X264.452 Y100.394 ;E16.48753
G1 X265.609 Y99.877 ;E16.55106
G1 X266.794 Y99.438 ;E16.61446
G1 X268.001 Y99.077 ;E16.67764
G1 X269.234 Y98.793 ;E16.74110
G1 X270.481 Y98.590 ;E16.80444
G1 X271.738 Y98.468 ;E16.86779
G1 X273.000 Y98.428 ;E16.93115
G1 X273.420 Y98.441 ;E16.95222
G1 X274.262 Y98.468 ;E16.99447
G1 X275.519 Y98.590 ;E17.05783
G1 X276.766 Y98.793 ;E17.12117
G1 X277.997 Y99.076 ;E17.18452
G1 X279.207 Y99.438 ;E17.24786
G1 X280.394 Y99.879 ;E17.31137
G1 X280.778 Y100.045 ;E17.33237
G1 X281.543 Y100.391 ;E17.37447
G1 X282.662 Y100.980 ;E17.43790
G1 X283.744 Y101.641 ;E17.50148
G1 X284.089 Y101.876 ;E17.52244
G1 X284.771 Y102.364 ;E17.56447
G1 X285.756 Y103.158 ;E17.62793
G1 X286.691 Y104.016 ;E17.69158
G1 X286.984 Y104.309 ;E17.71236
G1 X287.844 Y105.246 ;E17.77615
G1 X288.375 Y105.893 ;E17.81815
G1 X288.631 Y106.223 ;E17.83910
G1 X289.361 Y107.260 ;E17.90270
G1 X290.021 Y108.339 ;E17.96614
G1 X290.417 Y109.079 ;E18.00822
G1 X290.606 Y109.452 ;E18.02920
G1 X291.123 Y110.609 ;E18.09274
G1 X291.562 Y111.794 ;E18.15614
G1 X291.789 Y112.541 ;E18.19528

Repetier

Can't say what is so special on that gcode. Looks like 2 circles. Difference might be the direction switch is like a triangle, but I do not find that really special.There might be a chance that you haveREDUCE_ON_SMALL_SEGMENTSdefined somewhere. That will reduce speed for direction changes based on direction AND segment length. Smaller = Slower, and since backlash is small that might be the reason for a slowdown.

RAyWB

didn´t define that, only found it in motion.cpp
#ifdef REDUCE_ON_SMALL_SEGMENTS

what about jerk? i have jerk 7.0 cannot go higher because my moving table´s weight is around 12Kg.
if i increase jerk it´s like an earthquake...

another question regarding circles :

tried to mill some round pockets diameter 6mm with 3mm flute using G2 , worked but segments are clearly visible.

i found :
#define MM_PER_ARC_SEGMENT 1
#define MM_PER_ARC_SEGMENT_BIG 3

thats ok for printing but not good enough for milling

are float numbers allowed?
so may be 0.1 or smaller?

Repetier

Yes, the number gets converted to float anyway (in case it was integer), that is no problem.

Regarding jerk you might have seen the experimental defines

#define ALTERNATIVE_JERK

should give better behavior. REDUCE_ON_SMALL_SEGMENTS is for cases where you switch direction very fast having a small move between/at end that could cause bigger real jerks if direction changes are too fast in a row.

But the slowdown is then still a mystery. No luck on finding a short motion list you could debug with output created using echo as described above?

RAyWB

Ok,thanks.I´ll try to reduce the Gcode above to a part of just one circle to see if that still happens.Hope i´ll find the time to investigate next week.
another finding regarding G-code handling (killed some flutes yesterday):Cambam adds some single command line for spindle Speed ,for example just like this:G1 .....S1000G0 Z3G0 X....
So the line S1000 is a unknown command but the following G0 Z3 is not executedis there a Chance to catch this ?I think of something like void Commands::processSCode(GCode *com) {
switch ( com->S) .....
or just adding a if(com->hasS()) to processGCode before switch ( com->G)
what would allow to set Spindle Speed or laser intensity without a move.should be not hard to implement.(easiest would be just to do nothing when detecting the S-line :-) )

Repetier

S1000 gets ignored. Just run a test

S1000

M117 Hi

on Repetier-Host with this result:

10:11:02.865 : N41 M45122

10:11:02.865 : N42 S1000*26

10:11:02.865 : Printjob finished at 19.05.2016 10:11

10:11:02.865 : Printing Time: 0s

10:11:02.865 : Lines Send: 5

10:11:02.890 : N43 M117 Hi18

10:11:02.893 : N44 M104 T0 S0*17

10:11:02.893 : N45 M104 T1 S017

10:11:02.893 : N46 M84*45

10:11:02.975 : Disabled volumetric extrusion for extruder 0

10:11:02.975 : Disabled volumetric extrusion for extruder 1

10:11:02.976 : PrinterMode:FFF

10:11:02.981 : Unknown command:N42 S1000

10:11:03.158 : Successfully send push message.

As you see firmware detected it as unknown command and next line was send.

What did you use for sending it? Maybe the host/firmware combination makes a difference.

There is no branch to handle S only commands. We only support G/M/T as command identifier. Everything else gets ignored.

RAyWB

sent it by Repetier host,Printer mode CNC, and yes, the S1000 was ignored .My Problem is , that the move following the S1000 was not executed and this is reproducable.didn´t check it with a M117, but i´ll try thatwill post code and log this evening

RAyWB

Ok, skipping commands just happens in ASCII protocol.

see snippet from LOG using Ascii protocol:

17:55:20.874 : N24 M117 ETE 3m 04s *111
17:55:20.874 : N25 M105 *48
17:55:20.874 : N26 G1 Y155.5 *111
17:55:20.874 : N27 G1 X294 *122
17:55:20.874 : N28 G1 Y144.5 *97
17:55:20.874 : N29 G1 X280.4 *107
17:55:20.874 : ok 24
17:55:20.874 : N30 S1000 *63
17:55:20.874 : N31 G0 Z3 *114
17:55:21.342 : ok 25
17:55:21.342 : ok 26
17:55:21.342 : ok 27
17:55:21.342 : ok 28
17:55:21.342 : N32 M117 ETE 3m 00s *108
17:55:21.342 : N33 G0 X182.7 Y150 *46
17:55:21.342 : N34 G0 Z1 *117
17:55:21.342 : ok 29
17:55:21.342 : Error:Format error
17:55:21.342 : Resend:30
17:55:21.358 : ok
17:55:21.358 : skip 31
17:55:21.358 : ok
17:55:21.358 : Resend: N30 S1000 *63
17:55:21.358 : Resend: N31 G0 Z3 *114
17:55:21.358 : Resend: N32 M117 ETE 3m 00s *108
17:55:21.358 : Resend: N33 G0 X182.7 Y150 *46
17:55:21.358 : Resend: N34 G0 Z1 *117
17:55:21.358 : N35 G1 Z-0.4 F300 *22
17:55:21.358 : skip 32
17:55:21.358 : ok
17:55:21.358 : skip 33
17:55:21.358 : ok
17:55:21.358 : skip 34
17:55:21.358 : ok

with Repetier protocol it´s OK

RAyWB

but with repetier protocol i get :

22:19:07.496 : Error:Checksum required when switching back to ASCII protocol.

when using buttons assigned to

case UI_ACTION_X_ZERO:
if(!allowMoves) return UI_ACTION_X_ZERO;
GCode::executeFString(PSTR("G92 X0\n"));
break;

Repetier

I see I'm in compatibility vs. error hell.

I made more strict tests to detect errenous injection of wrong gcode throug communication errors. And now they are firing back. Will check it.

RAyWB

i added a handling for S commands, works in repetier protocol,
but still get format error in ascii protocol...
cannot see the trap, ist there something wrong in ascii parsing?

void Commands::processSCode(GCode *com) {
uint32_t codenum; //throw away variable

codenum=(com->S) ;
{
#if defined(SUPPORT_LASER) && SUPPORT_LASER
if (Printer::mode == PRINTER_MODE_LASER)
{
LaserDriver::intensity = constrain(codenum, 0, 255);
Com::printFLN(PSTR("Laserint:"), (int)LaserDriver::intensity);
}
#endif // defined
#if defined(SUPPORT_CNC) && SUPPORT_CNC
if (Printer::mode == PRINTER_MODE_CNC)
{
Com::printFLN(PSTR("Spindle s "),(int)codenum);
}
#endif // defined
}
}

RAyWB

back to original problem with reducing speed with backlash compensation:
seems to come from jerk , no improvement with alternative jerk
as it doesn´t appear with circles generated by Cam program i guess problem is located in
STL-file with too big segments.
i´ll try to change my model to smaller segments in CAD and see what happens

here´s the log:

10:17:33.216 : N912 G1 X291.517 Y113.106 F2400 *110
10:17:33.216 : N913 G1 X291.795 Y114.315 *0
10:17:33.216 : N914 G1 X291.994 Y115.535 *13
10:17:33.216 : N915 G1 X292.113 Y116.763 *10
10:17:33.216 : N916 G1 X292.153 Y118 *31
10:17:33.216 : N917 G1 X292.113 Y119.237 *3
10:17:33.216 : N918 G1 X291.994 Y120.465 *3
10:17:33.216 : N919 G1 X291.795 Y121.685 *0
10:17:33.231 : ID:537350200
10:17:33.231 : N920 M104 T0 S0 *10
10:17:33.231 : vStart/End:417/417
10:17:33.231 : accel/decel steps:1/1/3
10:17:33.231 : st./end speed:0.7/0.7
10:17:33.231 : Flags:146
10:17:33.247 : joinFlags:5
10:17:33.247 : ID:537350200
10:17:33.247 : Delta 0 3 0 0
10:17:33.247 : Dir:36
10:17:33.247 : Flags:18
10:17:33.247 : fullSpeed:0.70
10:17:33.247 : vMax:417
10:17:33.247 : Acceleration:8.96
10:17:33.263 : Acceleration Prim:537600
10:17:33.263 : Remaining steps:3
10:17:33.263 : LimitInterval:50350
10:17:33.278 : Move distance on the XYZ space:0.00
10:17:33.278 : Commanded feedrate:40.00
10:17:33.294 : Constant full speed move time:151050.00
10:17:33.294 : ID:537339140
10:17:33.294 : vStart/End:1921/1921
10:17:33.294 : accel/decel steps:876/876/6589
10:17:33.309 : st./end speed:2.5/2.5
10:17:33.309 : Flags:146
10:17:33.309 : joinFlags:5
10:17:33.309 : ID:537339140
10:17:33.309 : Delta 148 6589 0 0
10:17:33.309 : Dir:60
10:17:33.309 : Flags:18
10:17:33.309 : fullSpeed:40.00
10:17:33.325 : vMax:30746
10:17:33.325 : Acceleration:12007.04
10:17:33.325 : Acceleration Prim:537600
10:17:33.325 : Remaining steps:6589
10:17:33.341 : LimitInterval:683
10:17:33.341 : Move distance on the XYZ space:8.58
10:17:33.341 : Commanded feedrate:40.00
10:17:33.356 : Constant full speed move time:4506555.00
10:17:33.356 : Echo:N912 G1 X291.52 Y113.11 F2400.00
10:17:33.356 : N921 M104 T1 S0 *10
10:17:33.356 : N922 M140 S0 *76
10:17:33.356 : ID:537339280
10:17:33.372 : vStart/End:167/167
10:17:33.372 : accel/decel steps:1/1/3
10:17:33.372 : st./end speed:0.4/0.4
10:17:33.372 : Flags:146
10:17:33.387 : joinFlags:5
10:17:33.387 : ID:537339280
10:17:33.387 : Delta 2 3 0 0
10:17:33.387 : Dir:55
10:17:33.387 : Flags:18
10:17:33.387 : fullSpeed:0.40
10:17:33.387 : vMax:168
10:17:33.403 : Acceleration:17.92
10:17:33.403 : Acceleration Prim:537600
10:17:33.403 : Remaining steps:3
10:17:33.403 : LimitInterval:124381
10:17:33.419 : Move distance on the XYZ space:0.01
10:17:33.419 : Commanded feedrate:40.00
10:17:33.419 : Constant full speed move time:373143.84
10:17:33.419 : ID:537339420
10:17:33.434 : vStart/End:1872/1872
10:17:33.434 : accel/decel steps:464/464/929
10:17:33.434 : st./end speed:2.5/2.5
10:17:33.434 : Flags:146
10:17:33.450 : joinFlags:5
10:17:33.450 : ID:537339420
10:17:33.450 : Delta 148 929 0 0
10:17:33.450 : Dir:63
10:17:33.450 : Flags:18
10:17:33.465 : fullSpeed:40.00
10:17:33.465 : vMax:29957
10:17:33.465 : Acceleration:1781.72
10:17:33.465 : Acceleration Prim:537600
10:17:33.465 : Remaining steps:929
10:17:33.481 : LimitInterval:701
10:17:33.481 : Move distance on the XYZ space:1.24
10:17:33.481 : Commanded feedrate:40.00
10:17:33.497 : Constant full speed move time:651555.31
10:17:33.497 : Echo:N913 G1 X291.80 Y114.31
10:17:33.497 : N923 M84 *55
10:17:33.497 : N924 M105 *8
10:17:33.497 : ID:537339420 MJ:40.00
10:17:33.497 : ID:537339420
10:17:33.512 : vStart/End:1872/29957
10:17:33.512 : accel/decel steps:832/1/929
10:17:33.512 : st./end speed:2.5/40.0
10:17:33.512 : Flags:146
10:17:33.528 : joinFlags:7
10:17:33.528 : ID:537339560
10:17:33.528 : vStart/End:30345/1896
10:17:33.528 : accel/decel steps:1/854/937
10:17:33.543 : st./end speed:40.0/2.5
10:17:33.543 : Flags:146
10:17:33.543 : joinFlags:5
10:17:33.543 : ID:537339560
10:17:33.543 : Delta 106 937 0 0
10:17:33.543 : Dir:63
10:17:33.559 : Flags:18
10:17:33.559 : fullSpeed:40.00
10:17:33.559 : vMax:30346
10:17:33.559 : Acceleration:1751.87
10:17:33.559 : Acceleration Prim:537600
10:17:33.575 : Remaining steps:937
10:17:33.575 : LimitInterval:692
10:17:33.575 : Move distance on the XYZ space:1.24
10:17:33.575 : Commanded feedrate:40.00
10:17:33.590 : Constant full speed move time:648970.68
10:17:33.590 : Echo:N914 G1 X291.99 Y115.54
10:17:33.699 : ID:537339700
10:17:33.699 : vStart/End:1913/1913
10:17:33.715 : accel/decel steps:471/471/943
10:17:33.715 : st./end speed:2.5/2.5
10:17:33.715 : Flags:146
10:17:33.715 : joinFlags:5
10:17:33.715 : ID:537339700
10:17:33.731 : Delta 64 943 0 0
10:17:33.731 : Dir:63
10:17:33.731 : Flags:18
10:17:33.731 : fullSpeed:40.00
10:17:33.731 : vMax:30612
10:17:33.731 : Acceleration:1733.28
10:17:33.746 : Acceleration Prim:537600
10:17:33.746 : Remaining steps:943
10:17:33.746 : LimitInterval:686
10:17:33.746 : Move distance on the XYZ space:1.23
10:17:33.762 : Commanded feedrate:40.00
10:17:33.762 : Constant full speed move time:647700.12
10:17:33.762 : Echo:N915 G1 X292.11 Y116.76
10:17:33.777 : ID:537339840
10:17:33.777 : vStart/End:1921/1921
10:17:33.777 : accel/decel steps:474/474/950
10:17:33.793 : st./end speed:2.5/2.5
10:17:33.793 : Flags:146
10:17:33.793 : joinFlags:5
10:17:33.793 : ID:537339840
10:17:33.793 : Delta 21 950 0 0
10:17:33.793 : Dir:63
10:17:33.793 : Flags:18
10:17:33.809 : fullSpeed:40.00
10:17:33.809 : vMax:30746
10:17:33.809 : Acceleration:1731.14
10:17:33.809 : Acceleration Prim:537600
10:17:33.824 : Remaining steps:950
10:17:33.824 : LimitInterval:683
10:17:33.824 : Move distance on the XYZ space:1.24
10:17:33.840 : Commanded feedrate:40.00
10:17:33.840 : Constant full speed move time:649743.06
10:17:33.840 : Echo:N916 G1 X292.15 Y118.00
10:17:33.840 : ID:537339980
10:17:33.855 : vStart/End:112/112
10:17:33.855 : accel/decel steps:0/0/2
10:17:33.855 : st./end speed:0.3/0.3
10:17:33.855 : Flags:146
10:17:33.871 : joinFlags:5
10:17:33.871 : ID:537339980
10:17:33.871 : Delta 2 0 0 0
10:17:33.871 : Dir:22
10:17:33.871 : Flags:18
10:17:33.871 : fullSpeed:0.28
10:17:33.871 : vMax:112
10:17:33.887 : Acceleration:9.33
10:17:33.887 : Acceleration Prim:373333
10:17:33.887 : Remaining steps:2
10:17:33.887 : LimitInterval:186843
10:17:33.902 : Move distance on the XYZ space:0.00
10:17:33.902 : Commanded feedrate:40.00
10:17:33.902 : Constant full speed move time:373687.50
10:17:33.918 : ID:537340120
10:17:33.918 : vStart/End:1921/1921
10:17:33.918 : accel/decel steps:474/474/950
10:17:33.918 : st./end speed:2.5/2.5
10:17:33.918 : Flags:146
10:17:33.933 : joinFlags:5
10:17:33.933 : ID:537340120
10:17:33.933 : Delta 21 950 0 0
10:17:33.933 : Dir:62
10:17:33.933 : Flags:18
10:17:33.949 : fullSpeed:40.00
10:17:33.949 : vMax:30746
10:17:33.949 : Acceleration:1731.14
10:17:33.949 : Acceleration Prim:537600
10:17:33.949 : Remaining steps:950
10:17:33.965 : LimitInterval:683
10:17:33.965 : Move distance on the XYZ space:1.24
10:17:33.965 : Commanded feedrate:40.00
10:17:33.980 : Constant full speed move time:649743.06
10:17:33.980 : Echo:N917 G1 X292.11 Y119.24
10:17:33.980 : ID:537340260
10:17:33.996 : vStart/End:1913/1913
10:17:33.996 : accel/decel steps:471/471/943
10:17:33.996 : st./end speed:2.5/2.5
10:17:33.996 : Flags:146
10:17:33.996 : joinFlags:5
10:17:33.996 : ID:537340260
10:17:34.011 : Delta 64 943 0 0
10:17:34.011 : Dir:62
10:17:34.011 : Flags:18
10:17:34.011 : fullSpeed:40.00
10:17:34.011 : vMax:30612
10:17:34.027 : Acceleration:1733.28
10:17:34.027 : Acceleration Prim:537600
10:17:34.027 : Remaining steps:943
10:17:34.027 : LimitInterval:686
10:17:34.043 : Move distance on the XYZ space:1.23
10:17:34.043 : Commanded feedrate:40.00
10:17:34.043 : Constant full speed move time:647700.12
10:17:34.058 : Echo:N918 G1 X291.99 Y120.46
10:17:34.058 : ID:537340400
10:17:34.058 : vStart/End:1896/1896
10:17:34.074 : accel/decel steps:468/468/937
10:17:34.074 : st./end speed:2.5/2.5
10:17:34.074 : Flags:146
10:17:34.074 : joinFlags:5
10:17:34.074 : ID:537340400
10:17:34.074 : Delta 106 937 0 0
10:17:34.074 : Dir:62
10:17:34.089 : Flags:18
10:17:34.089 : fullSpeed:40.00
10:17:34.089 : vMax:30346
10:17:34.089 : Acceleration:1751.87
10:17:34.089 : Acceleration Prim:537600
10:17:34.105 : Remaining steps:937
10:17:34.105 : LimitInterval:692
10:17:34.105 : Move distance on the XYZ space:1.24
10:17:34.121 : Commanded feedrate:40.00
10:17:34.121 : Constant full speed move time:648970.68
10:17:34.136 : Echo:N919 G1 X291.80 Y121.68

RAyWB

update : Stl changed to very small segments, still same behavior

Speed changed to st./end speed:0.3/0.3 in turnover points

Repetier

Any idea what 0.3 is? If I'm right your jerk is 5 resulting in 2.5 mm start/end speed.

Commanded speed is is 40mm/s so no need to go lower. safeSpeed would be 2.5 so if anything puts it down it must be computeMaxJunctionSpeed() function returning lower. So adding a print here with id might show if that is the case and then it should be easy to find the formula causing it.

I have just released a new development version where I fixed the communication error you had plus some other improvements. It also simplifies now minimum speed handling. Most of the code has been removed as I now check in bresenham for it allowing nearly any speed you want. Was a problem with CNC/laser sometimes that minimum speed forced higher speeds as wanted.

RAyWB

0.3 in my setup is z-jerk, will change it to see if value in log also changes.
also will try the development release tomorrow.

RAyWB

youre right, happens in computeMaxJunctionSpeed()
i added some prints, found it happens here:

float jerk = sqrt(dx * dx + dy * dy) * lengthFactor;
Com::printFLN(PSTR("jerk "),(int)(jerk100));
#endif // ALTERNATIVE_JERK
#endif // DELTA
if(jerk > Printer::maxJerk) {
{factor = Printer::maxJerk / jerk; // always < 1.0!
Com::printFLN(PSTR("jerk>pJerk "),(int)(factor100));}
if(factor * maxJoinSpeed * 2.0 < Printer::maxJerk)
{factor = Printer::maxJerk / (2.0 * maxJoinSpeed);
Com::printFLN(PSTR(" factor<pjerk "),(int)(factor*100));}
}
......
previous->maxJunctionSpeed = maxJoinSpeed * factor; // set speed limit
Com::printFLN(PSTR("speed limit"),previous->maxJunctionSpeed);

so Log says :
23:50:47.729 : jerk 257 //2.57
23:50:47.729 : N56 G1 X265.767 Y135.735 *59
23:50:47.729 : speed limit40.00
23:50:47.729 : ok 49
23:50:47.729 : N57 G1 X264.633 Y135.228 *50
23:50:47.729 : jerk 254 //2.54
23:50:47.729 : speed limit40.00
23:50:47.729 : ok 50
23:50:47.729 : jerk 258 //2.58
23:50:47.745 : N58 G1 X263.548 Y134.657 *56
23:50:47.745 : speed limit40.00
23:50:47.745 : ok 51
23:50:47.745 : jerk 5563 //55.63
23:50:47.745 : jerk>pJerk 8 //0.08
23:50:47.745 : N59 G1 X262.49 Y134.011 *8
23:50:47.745 : speed limit3.59
23:50:47.745 : jerk 5748 //57.48
23:50:47.745 : jerk>pJerk 8 //0.08
23:50:47.760 : speed limit3.48
23:50:47.760 : ok 52
23:50:47.760 : jerk 258 //2.58
23:50:47.760 : N60 G1 X261.472 Y133.294 *53
23:50:47.760 : speed limit40.00
23:50:47.760 : ok 53
23:50:47.760 : N61 G1 X260.521 Y132.528 *51


values are *100 correct ones in comments

so it seems backlash compensation causes high jerk values .
do you have any idea how to solve this?