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Author Topic: Almost there: Laser reacts strange around 1% power (and traps for beginners)  (Read 115 times)
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« on: November 08, 2019, 11:32:08 AM »

Hi there
I am new here and I came from Mach 3 because the M03 and M05 commands are to slow for laser and M10/11 are not supported by the Pokeys57C NC.
After quite some twists and long hours I have now the laser running and can control it from Auggie.
One strange thing though:
Using the Pokeys GUI the Laser works perfect, 0% to 100%.
However, in Auggie after M03 the laser turns on at about 1% power, a light dot is visible.
When I fire anything below 1% it switches fully off, no dot any longer. Firing anything from 1% and above it works normal as it should.
I could not find it, Motor Tuning for PWM is set to no tickle, zero minimal, 100 maximal.
Why is this effect between 0% and 1%? I would like to get rid of it.

Traps for newbies:
- If you come from Mach 3: Do not forget to activate 8 Axes in Pokeys57C NC, not the 6 it normally has activated . Else you will only get it to work in Pokeys GUI but Auggie does nothing as it uses the 8th Axis to control the PWM (the price was about 8 hours of searching  Sad  )
- If you happen to have an OptLaser (cool Polish brand) with an Interface box for x-Carve and others using an Arduino based contoller: Remove the diode in the PWM signal cable in the box. Or the laser reacts eractic.
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« Reply #1 on: November 08, 2019, 04:14:33 PM »


 >>Why is this effect between 0% and 1%? I would like to get rid of it.

  The way the pokeys works is it gives me a control word that is integer from 0 - 100, 0 is fully off, 100
is fully on. However, it is integer, so 0 is off, 1 is on at 1%, you cannot do .5% for example.

  I get around this here with an arduino programme d as a PWM convertor, so my PWM from auggie goes
into this arduino and it has a screen that allows me to select 0 - 100% of the incoming. So if I need .5%
I can set the arduino to 50% of incoming and use 1% in auggie. If I need 100 levels from 0 - 5, I can set auggie
to 100% and set the arduino post processor to 5%, I now get 0-5 in 100 levels..

  So your 1% dot is simply the lowest Auggie can do and is your laser at 1%.
How powerful is your laser? Usually 1% is low enough for a start power. Its unfortuna te
that the power word is only 0-100 instead of 0-255 , but thats in the pokeys hardware
for the realtime pwm control.


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« Reply #2 on: November 09, 2019, 02:42:32 AM »

Hello Art

Thank you for your answer.
My Laser has 6 Watt so it does not burn anything at 1%. It is just a 'cosmetic' problem, I wanted to understan d if I do something wrongly(and learn).
If I understan d you correctly then it seems that M03 switches the Laser to the minimal 1% (I see the dot). If I Testfire with a setting of 0.9% or below it sets the laser for this time to 0% (temporari ly 'overrides' M03 so to say).

Thanks a lot for all your time to develop this and to help the users to get it to work. This is highly appreciat ed.
Best greetings from Switzerla nd.

PS: regarding the 8th axis:
The point where the penny dropped came when I was googleing to find more info on my possible error. I found your video 'AuggieLas er1' in your YouTube channel which emphasize d the 8th axis usage. This was so good that it finally made 'klick' in my head.
It would be of advantage for other newbies to put this link on the  page as well.   
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« Reply #3 on: November 09, 2019, 07:52:09 AM »

Hi Roman:

>>If I understan d you correctly then it seems that M03 switches the Laser to the minimal 1% (I see the dot). If I Testfire with a setting of 0.9% or below it sets the laser for this time to 0% (temporari ly 'overrides' M03 so to say).

  The M03 does a couple things. Many lasers need a  pre-ignition pulse to keep them
ready to fire. This is called a tickle, and Auggie does a 1ms tickle while m3 is on,
you can change this to 0 I think in the settings.

Couple things worth knowing.. ...

  If M3 is on, it also tells Auggie to fire the laser whenever a G1 move is in progress. If an
augment image is loaded ( The Aug light is flashing ), then that firing during G1 will not
happen if the motion is outside the image field, and when firing the power will be a scaled
grey scale value. A 255 in the image will fire at the Power Sliders value, and less than 255
will fire at pixel/255 * SliderPow er.

  The button "Dist. Cor" under the laser power sets Distance Correctio n mode, in this mode
the power of the laser will be corrected by speed. Its important to know how this works..

  Lets say you command F1000 as your feedspeed . Also lets assume your power slider
is set to 50% for this example. Lets say the next line executed in your code is
G1X100 , the speed at start is obviously 0, so the laser power is zero as well. As the axis
speeds up to do the move, the power will be  ("instant speed" / "requested speed" ) * PowerSlid er.
  So if the axis hits the 1000mm/min called for the power output will be 50% as requested
by the slider. If you simply turn on a laser and do the move without distance correctio n, the
accelerat ion zone of the move will be very burnt as the slow parts of the move get more
radiation . This is why many CNC programs burn at the corners of squares. Distance Correctio n
looks instead to how far one would move at full speed of F1000, it then takes the distance
we will actually move in the next ms, and scales the power to make sure the same power
is spent on each ms of the move. As lasers aren't completel y linear in output this correctio n
isn't perfect but definitel y worth using in most situation s.

  An important note here, if you command F5000 for example, and the fastest your axis
can do on this move is 500, the power will never exceed 10%. It is important to make sure
your Feedrate commands can be achieved if you wish to get proper power. I often run without M3
for a few minutes and watch the actual motions feedrate to see what I should be commandin g
to make them match as best I can. This will make the entire burn more even and gives me very
good results. 

  It is also important, if one wishes best performan ce to understan d Auggies trajector y planning,
unlike Mach3, Auggie is 6th order. This makes a differenc e in the way one must tune their axis
to get best performan ce. Because 6th order planning  doesnt use accelerat ion in the same way
as Mach3, your accel setting will normally not be as Mach3's is. In Mach3 you set a maximum
accel to make sure you dont stall during motion, in Auggie you set it as high as you can for
jogging only. If you use the keyboard jog you can see the effects of accel. The higher you can make
it the better so raise it while testing jogging between changes and make it so its fast and peppy
at startup but not quite to stalling from trying to start too quickly.   The reason you do this
is because Jog doesnt use 6th order, so your setting the max accel your motor can handle
without correctio n. Auggies Jerk controlle r will then use whatever accel it needs , even if much higher
than mach3 can accept and limit the speed and accel by jerk formula's.

   After doing this you run Gcode while adjusting MaxJerk setting between test runs. If set too low
on a small stepping Gcode, something that moves in jerky direction al changes, the axis will
jerk around slowly as it tries to keep jerk low. As you increase the max jerk, the axis will all
start to smooth out and go faster. This jerk setting can be large or small depending on the system,
my galvo for example is set to 25,000,000 and moves very very fast. Typically 25000mm/min
is what I run in Gcode. My Cartesian table though, needs a setting of 50,000 to make it move
quick and smooth , but not jerk. Too low and some jobs go very slow and jerky. So if you find
motion slow and jerky, raise the maxjerk setting, dont be shy about how much, start with 1000
and make the changes smaller or larger by result.   The biggest mistake users of Auggie make is
not understan ding how the jerk limit works, and it makes a huge differenc e in performan ce. Its
not unusual for a user to report the smoothest motion they have ever seen on their system, others
find no differenc e from Mach3, its a matter of tuning and of the system mass and such.

  I do occasiona lly cut a job and find it too jerky and raise the Jerk setting or too rounded on corners
so I lower the setting. Unlike Mach3 Auggie will not blend motions together to get speed, instead
it will put a small circular radius between lines sized as per jerk settings to keep the energy
of the move low as it goes around each radial bend.

   Another thing to consider is the lookahead, I set mine to 500 at times, on small line code this
speeds up things considera ble. Heres why. Auggie is a replannin g planner. Imagine you send
a G1X100 move. Auggie on reception plans the move entirely from start to end making sure
velocity is zero at the end and all jerk constrain ts are satisfied . It then starts to move. The max
speed after all the calcs is say..100m m/min.

  Imagine now that the next line of code is G1X200. Auggie is now stepping into the start
of the X move as it recieves this move. It will now go back and replan the all the moves including that X move. It
now knows the end position of that move will be 200. The only way to ensure a smooth motion
is to now replan everythin g forward taking jerk into account to make a new motion waveform.
  After the first move the top speed was going to be 100, but now, it knows the increased distance
so the move ends up doing the full F300 commanded . So if you have complex code say a wiggly
contour of something, the more lines it see's , the higher the end speed of all of them as
Auggie can create a very long, complex motion waveform that takes into account all the necessary
blending and added curvature s.
  (there is a statistic s button that switches the toolpath to an oscillosc ope view of the jerk waveforms .
It wont make much sense to you normally, but if you switch it on and command a G1X5 or something
youll see the jerk waveform of the moves if you wish to play with what your system is doing
jerkwise and how moves blend. )

   My 10 watt laser ( cartesion table) did the following cut .. as an example of what a 10 watt can do
with all correctio ns and doing photo engraving .


* Laser10Watt.jpg (3563.15 KB, 4128x3096 - viewed 24 times.)
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