Feed stops when commanding new spindle speed

Hi,

I'm trying to eliminate resonance of the workpiece with code such like this:
G97 S500 M3
G0 X100 Z2
G1 W-2 S400
G1 W-2 S500
G1 W-2 S400
G1 W-2 S500
...etc

It works, but on every line the feed stops until the spindle is up to the new speed, ruining the surface finish. How do I make it so that the movement is smooth?
The machine is a Puma 400 LM with Fanuc 18i-T control.

THANKS A LOT!!!

generally you can't. the machine waits for the spindle speed to be whatever is programmed before continuing. all lathes do that.
you could try either smaller speed increments/decrements or try G96, again with small increments.
there might be a parameter you could change to tell it not to wait for the speed signal to complete before continuing.
look in the parameter manual for the section on parameters relating to the spindle and/or M.S.T functions.

update:

I found only 1 parameter that may help....

3708 bit 0 SAR
The spindle speed arrival signal is:
0 : Not checked
1 : Checked

if you make 3708 bit 0 = 0 it may solve your problem.....

update update:

there's another one that may be more suitable....

3715 bit 0 NSAx
This parameter specifies an axis for which confirmation of the spindle
speed reached signal (SAR) is unnecessary when a move command is
executed for the axis. When a move command is issued only for an axis
for which 1 is set in this parameter, the spindle speed reached signal
(SAR) is not checked.
0 : Confirmation of SAR is necessary.
1 : Confirmation of SAR is unnecessary.

this parameter has 8 bits for each axis.
find the one for Z axis and set it to xxxxxxx1 (x=ignore)
then you should be able to change the speed randomly and the Z axis movement isn't affected.

You have been very helpful, I will try your suggestions at work on monday. I'll also post my resonance eliminator macro in case somebody will find it useful...

Late update: 3708 bit 0 SAR did the trick. The other parameters did not work. Thanks a lot!

glad you got it sorted. please post that macro you mentioned above. I'm sure many people here will find it interesting :-)