Pauses in motion on the M10/M11 commands

[cncdrive]

What do you mean by "the problem is back"? It came back because of what?

The spindle control is not syncronous motion, it never was syncronous, because it is controlled by the M3 and M4 and M5 text macros which macros when executed the motion controller must flush all of the motion to finish them and then execute the macro on the PC side and then can continue the g-code execution. This is not a problem for a spindle control, but can be for a laser. But M3, M4 and M5 are not for laser control.
And this can't come back as a problem since it was always like this.

For laser there are the M10/M11 commands which are motion syncronous commands and which executes between the movements without pause.

If there is a decceleration at the end of the motion depends on the trajectory settings, the CV parameters.
For example if the connection angle is set to 89° in the CV parameters, but the connection angle is 90°between the 2 lines then the controller will deccelerate to the connection point.
If the angle is set to 91°with the same example then it will not deccelerate, but will blend the path using the CV parameters which can still mean some sort of decceleration if the feedrate can't be physically kept using the set parameters, but usually is will be then not a full decceleration, how much it will deccelerate and how the path can be followed depends on the actual g-code and the other CV parameters.

[RJS]

Thank you for the explanation, I can understand how, when making a direction change greater then the stop at angle degrees it would need to decelerate and accelerate again. I have tried setting between 89 and 100 degrees and it still decelerates between arcs of what I believe are less then 90 degrees. For example, in the following g-code it slows from 1500mm/m to below 1000mm/m as it processes the code in red below.

T0 : 0.0 )
( T4 : 3.175 )
G21 G90 G91.1 G64 G40
G0 Z3.0
( T4 : 3.175 )
T4 M6
( Profile1 )
G17
M3 S15000
G0 X70.9375 Y268.007
G0 Z1.0
G1 F500.0 Z-0.75
G3 F1700.0 X75.5915 Y225.6216 I1068.8105 J95.9078
G2 X75.5919 Y225.6181 I-2.8882 J-0.3753
G1 X75.8793 Y223.3856
G2 X75.8802 Y223.3782 I-2.8887 J-0.3718
G1 X76.1619 Y221.145
G2 X76.1621 Y221.1433 I-2.8896 J-0.3644
G2 X76.7116 Y216.6594 I-765.7692 J-96.1219
G1 X76.7833 Y216.0654
G1 X77.1673 Y212.8911
G1 X77.271 Y212.0503
G1 X77.3835 Y211.1545
G1 X77.5062 Y210.2021
G1 X77.6417 Y209.1857
G1 X77.6587 Y209.0606
G2 X77.659 Y209.0589 I-2.8858 J-0.3934
G3 X78.4931 Y203.6631 I146.2699 J19.8486
G1 X78.6158 Y202.9614
G1 X78.6783 Y202.6103
G1 X78.8113 Y201.8757
G1 X78.8275 Y201.7872
G1 X78.8964 Y201.4133
G1 X78.9667 Y201.0355
G1 X79.1149 Y200.2498
G1 X79.1519 Y200.0558
G1 X79.3094 Y199.238
G1 X79.3897 Y198.8258
G1 X79.5585 Y197.9685
G1 X79.6448 Y197.5347
G1 X79.733 Y197.0937
G1 X79.917 Y196.182
G1 X80.3165 Y194.2315
G1 X80.4183 Y193.7401
G1 X80.8605 Y191.6247
G3 X82.5672 Y185.5319 I47.036 J9.8898
G3 X85.0503 Y179.6988 I47.3675 J16.7191
G1 X85.1956 Y179.4122
G1 X91.6861 Y168.6468
G2 X91.6873 Y168.6448 I-2.4942 J-1.5038
G2 X95.2083 Y160.4748 I-28.3503 J-17.0618
G2 X95.2092 Y160.4715 I-2.8054 J-0.7827
G2 X96.4125 Y151.6545 I-31.7932 J-8.8297
G2 Y151.6533 I-2.9125 J-0.0011
G1 Y9.9973

this is the area circled in the attached picture

This happens whether I am using the laser commands or the spindle commands. Is this normal? If so how can better maintain a constant velocity?

Thanks,

Randy

[cncdrive]

Thanks for the example code.
Could you please also post your profile file?
Then I will run some tests to see why is the decceleration happening.

[shad]

Hello Balazs!
I agree with RJS.
My customers consistently notice about deceleration and acceleration on the joints of the arcs. Independent from profile settings and CV settings.
This issue only on arcs joins and even at small angle degrees between arcs. Arc->Line and Line->Arc joints are fine.
The problem goes away if we set acceleration value more then 5000 mm/sec2. But you understand of course that this is an unrealistic value for the machine.
This issue is very problematic for plasma cutting. Cut quality on this places is bad - we have a biggest kerf width (the dimensions of the part become wrong) and a lot of dross on the bottom side.

[RJS]

My profile is attached.

[RJS]

are there any updates on this?

[Robertspark]

What settings do you have for corner error max?

[Robertspark]

viewtopic.php?f=16&t=810
Consider the above thread .... Give it a try and see if it improves things

Note the profile listed earlier has a max corner error setting of 0.03 which means your machine must slow down with a change of direction this will I suspect include arcs in sequence too

[Robertspark]

http://www.plasmaspider.com/viewtopic.php?f=52&t=23770

There is a detailed post of mine here on 24th October that may be worth a read and consideration too

[RJS]

Robertspark - thanks for the info!

I tried adjusting the settings per your posts and it does reduce the problem some but uccnc is still deaccelerating and accelerating at what seems like each line of code with a arc even when the angle is well uder 89 degrees.

RJS