G38.x and acceleration (not stopping)

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10 years 4 months ago #75393 by andypugh

dgarrett wrote: Please note that ini.* hal pins are created too late to be used
in a [HAL]HALFILE (but they can be specified in a [HAL]POSTGUI_HALFILE


I had thought that the pins were "made" by motion, but it seems not.

Do you know which section of the docs do they appear in, for future reference?

They are regular hal pins rather than parameters? So they can be manipulated by a net, though won't be updated while a program is running?

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10 years 4 months ago #75405 by arhi
not working :(

the "syntax" goes but it ain't doing nothing :(
Code:
arhimed@linuxCNC:~/linuxcnc/nc_files$ cat ../configs/mill25d/custom_postgui.hal sets spindle-at-speed true net X-accel motion.analog-out-00 => ini.0.max_acceleration net Y-accel motion.analog-out-01 => ini.1.max_acceleration net Z-accel motion.analog-out-02 => ini.2.max_acceleration

and the g-code:
Code:
G17 G21 #<_X-Accel-original> = #<_ini[AXIS_0]MAX_ACCELERATION> #<_Y-Accel-original> = #<_ini[AXIS_1]MAX_ACCELERATION> #<_Z-Accel-original> = #<_ini[AXIS_2]MAX_ACCELERATION> T1 M6 (DEBUG, "default accel move") F500 G1 X50 G1 X10 (DEBUG, "no accel move") M68 E0 Q9999999 F500 G1 X50 G1 X10 (DEBUG, "slow accel move") M68 E0 Q1 F500 G1 X50 G1 X10 (DEBUG, "restored accel move") M68 E0 Q#<_X-Accel-original> F500 G1 X50 G1 X10 M2

all three moves are using exactly the same acceleration :( the acceleration value is not changed

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10 years 4 months ago #75406 by dgarrett

Do you know which section of the docs do they appear in, for future reference?

Code:
$ man milltask
linuxcnc.org/docs/2.7/html/man/man1/milltask.1.html
Also:
linuxcnc.org/docs/2.7/html/config/core-c...s.html#_ini_settings

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10 years 4 months ago #75407 by dgarrett

all three moves are using exactly the same acceleration
the acceleration value is not changed

Code:
But note that ini hal pins are not evaluated while a program is running.
forum.linuxcnc.org/forum/20-g-code/31025...pping?start=10#75376

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10 years 4 months ago #75409 by arhi
had to try :D
unfortunately looks like no way to change those values :(

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10 years 4 months ago #75412 by andypugh

arhi wrote: had to try :D
unfortunately looks like no way to change those values :(


You can change them, then run a program. You just can't change them while a program is running.

Try issuing the commands from MDI.

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10 years 4 months ago #75413 by arhi
will try that ... should help with G38 thing but not with everything else I wanted to use it for :(

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10 years 4 months ago #75415 by andypugh

arhi wrote: will try that ... should help with G38 thing but not with everything else I wanted to use it for :(


I am still failing to see why, if your Z-axis can achieve a higher acceleration than you have configured, you don't simply set the Z axis to use the high acceleration all the time?

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10 years 4 months ago #75417 by arhi
not that simple, my axis can deal with high acceleration up to a certain speed... for e.g. I can drive XY @F500 without any acceleration (my original 3d print firmware don't support acceleration at all) but over F500 it will skip steps .. I need this "jerking" moves (infinite acceleration) while 3d printing in order to "break the string of plastic" so for some moves infinite acceleration is required, for some other moves the acceleration is required as higher speeds are achieved that way .. also I want to have a slow speed move with infinite acceleration and high speed move with regular acceleration... I can have 2 heads in the same time, one depositing plastic, other one depositing silicone, while I'm depositing plastic I have a stepper driving the extruder so acceleration on all 4 axes is working ok and in sync, on the other hand for silicone I have on/off pressure valve and constant extrusion rate so can't have acceleration on the XY axes, it has to be uniform from start to stop, yes that requires slower move but it works .. now since the idea is to use both heads in the same print - first the plastic head make a scafold for few layers then silicone head fills it I need to be able to change acceleration mid print (hence those M20x codes I mention we normally use on printers) ... now for milling I doubt this is needed but I would like to move my printing to linuxcnc as well as I'm sure printing would benefit from better speeds I see linuxcnc is able to achieve (looking forward on how pats look like and adapting speed in corners etc..) + changing reconnecting motors from linuxcnc box to a reprap box is crap I already replaced 2 connectors :(

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10 years 4 months ago #75427 by Rick G

can drive XY @F500 without any acceleration (my original 3d print firmware don't support acceleration at all) but over F500 it will skip steps

Sounds like the best solution would be more powerful steppers / drivers to achieve the acceleration / speed you are looking for. Possible also look if you are using microstepping and go to a lower setting there.

Infinite acceleration is not really possible, always going to be limited by the machine.

Rick G

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