Laser max rate

[bucky]

Sure, here's the file. Any suggestions on smoothing parameters to try welcome.

[Houseman303]

G64 on.

if backlash compansation >0.001 switch off.

axis accel 0.5-0.9. you must testing.

see cnc12 manual for G64 smoothing

[bucky]

Thanks. I've read the section of the manual on smoothing and understand the idea of using smoothing in normal cases to prevent following small variations in the G-code, so the tuning parameters make more sense. Here the path is a straight line where the laser switches on and off, so I'm not really sure what smoothing is doing. I did get it to run, but it slows down to ~30ipm which makes a nice image but takes forever.

[Houseman303]

Path Control Mode and Look ahead feed- G61, and G64
Ideally one would like to have constant cutting speed during the work and
maximum accuracy. This ideal is physically not possible, similar as driving a
racecar on curvy roads is not possible with constant velocity. It is simply to
understand that it is needed to brake in the curves and accelerate on the
straight roads. If you would do the same speed in the curves as on the straight
road, the car will fly out of the curve and get an accident. With a CNC machine it
is the similar, constant speed and accuracy together are physically not possible.
It would require infinite acceleration to go through a corner from one direction
to another. In a CNC machine this would result in position/step loss of stepper
motors or high following error with servo’s. If the motion path to consist of
small lines (G1) it is even worse than driving a racecar, because there is a sharp
corner between every line. This is often the case with CAM generated motion
paths (g-code).
So a compromise has to be made. There are various options to choose the
optimum between accuracy and constant speed or fast speed versus jerkiness.
G61 puts the machining center into exact path mode, In G61, the motion
velocity between motion segments goes to zero, the end position in corners is
exactly reached, use this if you require maximum accuracy. When a work piece
consists of many small lines this gives a quite jerky/vibrating machine because
of the continuous acceleration-deceleration-stop behavior.

G64 is to be used for more smooth and fast motion.

create a rectangle in cad to test.
The settings in CNC12 will affect the corners of the rectangle when machining.
Set what is best for you, quality or rounding and speed.

[Houseman303]

Trumpf Laser has 140m/min axis speed. 1-10 G Acceleration

[suntravel]

IMHO the step/in Rate ist to low and probably the machine not sufficiently rigid.

I do Laser Images on my mill without smoothing faster than 100 ipm and no problems.

Uwe

[bucky]

Not much I can do about the rigidity, but any other suggestions?

[suntravel]

Dial in a higher step rate or use a reduction on the spindles.

Uwe