Problem bei Kreisbahnen

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07 Dec 2014 21:02 - 07 Dec 2014 21:39 #53785 by MarcusNM
Hallo liebe Community,

Ich habe eine kleine Desktop-CNC mit einer tb6600 Steuerung (nicht das komplette Board, sondern die einzelnen Treiber), Vexta pk266 Schrittmotoren die mit flexiblen Wellenkupplungen auf Trapezgewindespindeln TR12x3 befestigt sind, als Spindel eine Proxxon ibs/e. Das Ganze läuft im 1/8 Mikroschritt, Beschleunigung ist 300mm/s2 und 30mm/s Vorschubgeschwindigkeit. Geraden und Schrägen schafft die Maschine anstandslos, nur die Kreisbahnen bereiten mir Kopfzerbrechen.

Leider lässt sich momentan kein Bild hochladen. Aber die Kreise sehen aus wie Quadrate mit großen Radien und kurzen Geraden.
Auch bei einem sehr großen Kreis sind noch Kurze Geraden erkennbar.
Auf Anfrage kann ich ein Foto gern per Email zusenden.

Ich habe schon verschiedene Einstellungen ausprobiert, was die Geschwindigkeit und Beschleunigung angeht, aber das Fräsbild bleibt immer gleich.
Wenn ihr mehr Informationen benötigt, einfach schreiben.

Ich hoffe, hier weiß jemand eine Lösung, ich bin mit meinen Weisheiten am Ende.

Vielen Dank im voraus!
Last edit: 07 Dec 2014 21:39 by MarcusNM.

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07 Dec 2014 23:04 - 07 Dec 2014 23:22 #53788 by ArcEye
Replied by ArcEye on topic Problem bei Kreisbahnen
Hi

I suspect you need to use G64 P0.1 or very similar, assuming mm machine units being used

www.linuxcnc.org/docs/devel/html/gcode/gcode.html#sec:G64

EDIT:

Apologies read your post backwards, as being squares with rounded corners, not circles with straight lines.

If your code is generated by CAM, it probably is made up of short lines, you need to look at the new trajectory planner
www.linuxcnc.org/index.php/english/forum...stersprograms-wanted

However you will need G64 with that too to set the tightness of the control

regards
Last edit: 07 Dec 2014 23:22 by ArcEye.

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08 Dec 2014 00:28 #53789 by MarcusNM
Replied by MarcusNM on topic Problem bei Kreisbahnen
Thank you for answering so fast.

But this have not solved my problem.

Do you know something more to try out?

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08 Dec 2014 00:43 #53790 by ArcEye
Replied by ArcEye on topic Problem bei Kreisbahnen
How is your gcode produced?

Linuxcnc just follows the code it is asked to run.

If your code is produced by a CAM program that does not use G2 and G3 arcs, that is where the straight lines come from.

The new trajectory planner tries to overcome the problems with such code by path blending, which should give a smoother line and enable it to be run faster
because it is not running each individual segment as a separate line with acceleration at the start, then deceleration at the end before switching to the next segment.

regards

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08 Dec 2014 01:00 #53791 by ArcEye
Replied by ArcEye on topic Problem bei Kreisbahnen
This code is a classic 4 quadrant G2 circle

It should cut without any deviation to form a circle.

If that works, there is nothing wrong with your machine it is the code.
G17 G21 G8
G80
G90
F150 S600
M3
G4 P5

G00 Z2
G00 X0 Y0
G00 X0 Y50 Z2

G01 X0 Y50 Z-1 F50
G02 X50 Y0 I0 J-50 F150
G02 X0 Y-50 I-50 J0
G02 X-50 Y0 I0 J50
G02 X0 Y50 I50 J0

G00 Z2
M5

M2

regards

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08 Dec 2014 01:02 #53792 by MarcusNM
Replied by MarcusNM on topic Problem bei Kreisbahnen
I'm using estlcam. G2 and G3 are activated.

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08 Dec 2014 17:41 #53810 by ArcEye
Replied by ArcEye on topic Problem bei Kreisbahnen

I'm using estlcam. G2 and G3 are activated.


That does not mean they are being used properly.

Does the code posted cut a proper circle?

If so, generate a 100mm circle in esticam and see what that gives you, post it so we can see it too.

regards

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08 Dec 2014 18:28 #53812 by newbynobi
Replied by newbynobi on topic Problem bei Kreisbahnen
Das hört sich mehr nach rein mechanischen Problemen an.
Wie gross ist das Umkehrspiel?

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08 Dec 2014 20:42 #53815 by MarcusNM
Replied by MarcusNM on topic Problem bei Kreisbahnen
This is, what estlcam is generating. The tool is a 3mm Endmill.

G90 G64 P0.1
M03
G00 Z5.0000

(Nr. 1 Teil 1)
G00 X13.6492 Y13.5188
G00 Z0.5000
G01 Z-1.0000 F400 S20000
G03 X101.4973 Y49.4842 I36.3507 J36.4812 F1000
G01 X101.4998 Y49.9925
G03 X13.6492 Y13.5188 I-51.5000 J0.0075
G00 Z5.0000

M05
M30

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08 Dec 2014 21:05 #53817 by ArcEye
Replied by ArcEye on topic Problem bei Kreisbahnen
Hi

It looks about right, but it is always hard to follow CAM output precisely

Don't know why it needs to throw in a 0.5mm Y axis adjustment half way through with a G1 move though?

G03 X101.4973 Y49.4842 I36.3507 J36.4812 F1000
G01 X101.4998 Y49.9925
G03 X13.6492 Y13.5188 I-51.5000 J0.0075

The question remains, did the code I posted cut a clean circle without straight lines and does this code do the same.

If the answer is yes to both, need to look at the code you had problems with.

If no to both, then you may have some mechanical issue that needs tracking down, which shows itself in the combination of XY moves required to cut a circle.

regards

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