micro stepping issue

Hello,

Sorry for the double post but I have first posted my topic in stepconf wizard and it might not be the right place.... since the problem comes "after" stepconf wizard.

I have a weird problem... I had a stepper which was not working very well and giving a lot of "bumps" the bumps propagating to the entire machine and giving vibrations which nearly made it impossible to mill.

The driver (leadshine MA860H) was set up to run with 8 micro steps for this axis and by increasing to 16 (both on the driver and in stepconf wizard) what a surprise it runs smoothly and perfectly at full speed with a perfect smooth noise while tested within stepconf wizard... (linuxcnc 2.7.4) Joy joy joy

BUT it only does so under stepconf wizard when I run normaly under axis it behaves like it did before so the bumps are there again (i.e. like when I used 8 micro steps...) ... It seems the driver is not giving the double amount of steps...

why oh why ? Why does it behave differently under axis than under stepconf wizard ?

Many thanks in advance for the help you can provide.

for info the base period on the linuxcnc pc is 15000.

What do you have the SCALE variables set to in your .ini file (one per axis)?
Perhaps if you can attach your .ini file.

Hello Geoffs,

Many thanks for your quick answer.
Well I did not touch anything I did let stepconf wizzard generate the .ini

Here is what was generated.

By the looks of it each axis has the same scale, which is strange since the Z axis (axis_2) still is configured to be with 8 micro steps...

How do the SCALE values compare between configurations with 8 and 16 microsteps selected?

check your actiual ini file , stepconf may not have re-saved the file , and your scale values are different to what you think thay are set for .
stepconf is only meant for a quick get you started situation , after that learn Hal and hand edit your hal and ini files .

in the ini file the SCALE is the same namely 320... for all axes... It should be different between the first two axes and the last one... so yes it looks like the generated .ini file does not follow the .stepconf file....


Strange because the ini file was generated from scratch, I started from a blank conf...

So it looks like I have to change the INI file manually...

what should I set the scale to for a 16 micro steps drive and 1.8 degres per step so basically 3200 micro steps per revolution ?

what I don't get is that 320 should be the right setting for the SCALE value when running 16 micro steps and 200 steps per rev...

Here is how the INI files looks like for my Y axis

[AXIS_1]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 85.5005472035
MAX_ACCELERATION = 200.0
STEPGEN_MAXACCEL = 250.0
SCALE = 320.0
FERROR = 1
MIN_FERROR = .25
MIN_LIMIT = -0.001
MAX_LIMIT = 1200.0
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = 1.500000
HOME_LATCH_VEL = 1.500000
HOME_IGNORE_LIMITS = YES
HOME_SEQUENCE = 2

Any input ? i really need to get this machine working tomorrow monday and it is so frustrating to see it work perfectly under stepconf wizzard and vibrate when used under axis...

Is there anything under axis that limits the micro stepping that linuxcnc can generate ? Should all drivers have the same micro stepping or can it support a different micro stepping per driver ?

SCALE Specifies the number of pulses that corresponds to a move of one machine unit say an inch.
As shown here with a formula.
linuxcnc.org/docs/2.4/html/config_ini_config.html

what I don't get is that 320 should be the right setting for the SCALE value when running 16 micro steps and 200 steps per rev...

Have you checked that the scale is correct and that a g code move of say 10 results in a machine move of 10 units?
Machine units can be inch or mm.

Is there anything under axis that limits the micro stepping that linuxcnc can generate ? Should all drivers have the same micro stepping or can it support a different micro stepping per driver ?

The steps generation is not limited by Axis but by your hardware. The micro stepping can be different for each axis.



Rick G