Issues with 3-axis interpolation

[GeorgS]

This is my machine, I have 750W Servo motors, so the power isn't a problem. I just tried 1000 acceleration, the machine makes ugly noise and the work table starts to vibrate when doing short lines of the toolpath. Seems like the underconstruction is twisting die to the high forces of too high acceleration.

[GeorgS]

Still working on a solution.
Here a simple Gcode.
F is 4000mm/min. the rounded corners run with less than 1000 on acceleration 500. seems the problem is the CV setting but I don't find the problem. Mach and Beamicon run this code with F4000 constantly. Any ideas?

[Battwell]

sounds to me like your servos need tuning.
are the servos direct drive? or belt reduced.

[ger21]

500 accel is really quite low.

Mach and Beamicon run this code with F4000 constantly

Mach3 does a couple things to achieve this.
1) It sometimes exceeds the acceleration rates.
2) It doesn't always follow the path accurately.

[GeorgS]

I just set the acceleration to 1000, feedrate in the corners is still <1500
this is not influenced by the servo motors as you can see it even with uccnc in offline mode without machine..

[Battwell]

uccnc must slow down for the corners- the same way you slow your car down to drive around a corner, or you will skid off the road.
it will decelerate into the corner, round the corner, then accelerate away.

[hmnijp]

I just set the acceleration to 1000, feedrate in the corners is still <1500
this is not influenced by the servo motors as you can see it even with uccnc in offline mode without machine..

Maximum speed at corners is limited by centripetal acceleration.
You can calculate the maximum speed when moving along the radius using your acceleration using this simple formula
V[mm/min] = 60*sqrt(a[mm/s2] * R)

For a=500mm/s2 and R=10мм - maximum V = 4243 mm/min

But your path you've attached doesn't have a arcs(g2/g3 code) - it's a linear interpolation - lots of little linear segments (g1).

UCCNC smooths them out using the CV settings. Adds fillets to each corner. As a result, the maximum speed of movement will be limited by the size of all these small arcs. The smaller this fillets = the lower the maximum speed.
In Exact Stop mode, there are no fillets and the machine comes to a complete stop at every small corner of the path.

To increase the speed, you either need to draw the trajectory using large G2/G3 - here is an example similar to your trajectory - you can check it:

Code: Select all

G1X-76.198 F4000
G2 X-86.198 Y-23.46 I0. J10.
G1 Y23.46
G2 X-76.198 Y33.46 I10. J0.
G1 X76.198
G2 X86.198 Y23.46 I0. J-10.
G1 Y-23.46
G2 X76.198 Y-33.46 I-10. J0.
G1 X-1.725

or increase CV setting ("corner error" and other values) so that the UCCNC smooths out more.
For example 0.5LE, 5LAL, 10LUL, 0.25CE

The same thing happens with your other toolpaths - the maximum speed always depends on the size of this fillet.

Match3 moved faster because his trajectory didn't match those settings. He did acceleration and fillets more than set in the settings.

The reason for the terrible noise of your machine is also your trajectory - the movement turns into jerking in small segments. Set more smoothing and more acceleration. Try setting up your СAM to output large arc segments. But avoid lots of small arcs in the code - it will make the code slower than with small linear segments.

[fixebr]

Hello.
I have this code in one program:

Code: Select all

X-28.654 Y-32.777
X-26.983 Y-34.516
X-26.813 Y-34.702
X-22.813 Y-39.308
X-22.659 Y-39.495
X-19.384 Y-43.663
X-19.245 Y-43.849
X-15.963 Y-48.455
X-15.822 Y-48.664
X-12.499 Y-53.869
X-12.372 Y-54.079
X-9.74 Y-58.688
X-9.624 Y-58.904
X-6.815 Y-64.442
X-6.703 Y-64.677
X-4.274 Y-70.16
X-4.18 Y-70.387
X-2.18 Y-75.584
X-2.101 Y-75.807
X-0.346 Y-81.113
X-0.276 Y-81.343
X1.254 Y-86.853
X1.312 Y-87.082
X2.507 Y-92.346
X2.554 Y-92.579
X3.558 Y-98.248
X3.595 Y-98.496
X4.342 Y-104.451
X4.367 Y-104.704
X4.803 Y-110.626
X4.815 Y-110.873
X4.949 Y-116.576
Y-116.828
X4.78 Y-122.97
X4.767 Y-123.219

It is in G0, this is the transition to a new cutting point. Generated imachining, so I have no direct possibility to change it in the configurator.
When it is fulfilled, the machine makes several very strong jerks. How can I configure uccnc so that such blocks are performed smoothly?

[ger21]

Increase the max linear error setting.

[hmnijp]

Hello.
I have this code in one program:

It is in G0, this is the transition to a new cutting point. Generated imachining, so I have no direct possibility to change it in the configurator.
When it is fulfilled, the machine makes several very strong jerks. How can I configure uccnc so that such blocks are performed smoothly?

I use fusion 360, it gives similar code in "ADAPTIVE" strategy.
But I set up the postprocessor to output G64 parameters (CV settings).

For example, for a rough operation (accuracy is not important), inserts the code "G64 H0.5 L10 P20 Q0.5" These are very smooth movements.
But during the finishing pass, the code "G64 H0.05 L5 P10 Q0.02" is added. - high precision and sharp corners.

This happens automatically, because the postprocessor knows the type of operation, and inserts the code at the right moment.
Moreover, these settings may differ depending on the CAM settings - accuracy, finishing pass, stock to leave. All this data is passed to the post processor, you need to add a few lines of code to use it. You can do it in the SolidCAM too. Or change them in the UCCNC itself as needed.

Other CNC systems also have similar settings, standard HAAS and SIEMENS postprocessors do this too: