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Author Topic: The Laser Project.  (Read 835551 times)

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Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #1080 on: April 08, 2019, 03:35:17 AM »
Hi Wangine,

Quote
Also i will dont use DB25. TCP or USB probably. I allways hate db25 for alot of reason

I was referring to the DB25 output socket from the 57CNC v1.2.

(The output from your PC to the input to the 57CNC can be USB or Ethernet).

Quote
Why not a external PWM base timing. Exist a lot of controllers can easy pragramed with only some lines of code


It is not necessary to use a PWM controller chip, the 57CNC outputs the PWM perfectly.


Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline ART

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Re: The Laser Project.
« Reply #1081 on: April 08, 2019, 07:48:07 AM »
   The problem is not getting PWM, many boards offer a PWM output, the problem is always getting
the PWM to change during motion based on a photo. This requires the CNC program to deal with either
a photo or a data-file representing that photo. This is not a normal thing for a CNC program to do,
it requires handling data in realtime that a typical CNC program doesnt like to do, its busy enough
doing the motions and GCode translations.
   Mach4 will do it with an ESS , the capability is in the ESS's driver as Greg was kind enough to add
that capability for Laser users. Auggie will do it because it was designed from the start to control a
laser.
   You will find with lasers general CNC programs are difficult to coax into doing laser engraving of
photos just as Auggie is difficult to coax into doing normal CNC milling work. It can do so , but its
primary purpose is Laser.

  Luckily, if you wish to do any normal Milling , the PoKeys will work with Mach3 or Mach4. Auggie is
a free program so its just a good thing to have in the toolbox if you have a Laser capability on  a
Milling type configuration.

Art
Re: The Laser Project.
« Reply #1082 on: April 08, 2019, 01:50:52 PM »
Yes . I got that , i read entire topic. I notice , engraving is a tricky part and alot of work. Also i think the huge diference will be made by the photo editor software. As example a grayscale photo 8bit , any pixel have the 8 bit information , that can be easily converted to PWN value with low-high limits , so i think the software who convert the photo in GCODE will decide the final product.
What i found until now is , GIMP, inkscape and dotG but that only for 1bit information. I think exist alot of good software wich i didn't find yet.
 
Death is not the greatest loss in life. The greatest loss is what dies inside us while we live. @Norman Cousins
Re: The Laser Project.
« Reply #1083 on: April 10, 2019, 08:47:40 AM »
For those of you interested in laser diode engraving gray scale photos with Mach3, this video was done several years ago.   Uses hardware (a digital to analog controller) to generate an analog control voltage from Mach3's Z axis output.
https://www.youtube.com/watch?time_continue=9&v=LlDgTUm8Fi0
Re: The Laser Project.
« Reply #1084 on: April 15, 2019, 12:56:17 PM »
For those of you interested in laser diode engraving gray scale photos with Mach3, this video was done several years ago.   Uses hardware (a digital to analog controller) to generate an analog control voltage from Mach3's Z axis output.
https://www.youtube.com/watch?time_continue=9&v=LlDgTUm8Fi0
Thanks , like that i can doit by myself. I work with DSP microcontrollers for several years. http://www.ccsinfo.com/forum/viewtopic.php?t=46829  , response time 0.26ns . If you give me a free license on picengraver why not.
Death is not the greatest loss in life. The greatest loss is what dies inside us while we live. @Norman Cousins
Re: The Laser Project.
« Reply #1085 on: April 15, 2019, 12:59:51 PM »

  Luckily, if you wish to do any normal Milling , the PoKeys will work with Mach3 or Mach4. Auggie is
a free program so its just a good thing to have in the toolbox if you have a Laser capability on  a
Milling type configuration.

Art
AOther dumb question .It is a beter option to isolate the driver to PoKeys ? https://www.aliexpress.com/item/24V-to-5V-4-Channel-Optocoupler-Isolation-Board-Isolated-Module-PLC-Signal-Level-Voltage-Converter-Board/32951680568.html?spm=2114.search0104.3.152.14f55515ETy64f&ws_ab_test=searchweb0_0,searchweb201602_3_10065_10068_319_10892_317_10696_10084_453_454_10083_10618_10304_10307_10820_10821_537_10302_536_10843_10059_10884_10887_321_322_10103,searchweb201603_80,ppcSwitch_0&algo_expid=4149919f-93c3-4487-8eac-1d6905cfb143-22&algo_pvid=4149919f-93c3-4487-8eac-1d6905cfb143
Usualy that cheap pype of optocuplers have a huge noise and slow rise up .
Death is not the greatest loss in life. The greatest loss is what dies inside us while we live. @Norman Cousins

Offline ART

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Re: The Laser Project.
« Reply #1086 on: April 15, 2019, 03:45:49 PM »
I use opto's, the speeds really arent all that high in the scheme of things..

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #1087 on: September 25, 2019, 01:48:42 AM »
Here is some really useless information which may possibly be of curiosity…

I have in the past noticed that with laser engraved 8 bit images on wood that some white areas of the image can appear to be whiter than the natural colour of the background material and I have always put this down to being an optical illusion.
Recent tests have shown that at very low output levels a CO2 laser will (for want of a better word) bleach the natural colour of the wood being engraved and actually whiten the background. Although this effect can easily be reproduced during PWM output power controlled engraving when increasing the white level threshold above 0% I have not yet discovered any practical application.

This laser engraved image, I think, clearly shows the white areas to be whiter than the original background.

I would appreciate others comments on this phenomenon.

Tweakie.


Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: The Laser Project.
« Reply #1088 on: October 02, 2019, 07:57:51 PM »
Hopeful for some insight on my results so far. But before that thanks to all commenting and to tweakie for the work therein  :)

Setup:
2 watt laser
TIP 120 power transistor driving it from parallel port
Laser is on port 7 active high (not low)

Questions:
1. Laser is active high not low is this a problem?
2. Laser is on at initial start up. Can digital trigger be set default low on launch to keep this off initially?
3. Edge bands on the image attached... what's causing this?

Thanks all!
R

Offline Tweakie.CNC

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Re: The Laser Project.
« Reply #1089 on: October 03, 2019, 01:48:43 AM »
Hi,

A laser switched by an active High signal is not a problem.
The LPT Parallel Port (for reasons best known to itself) always starts up with some pins in the High state and some pins in the Low state. For this reason you may need to invert the signal feeding your TIP 120 (or possibly choose a different LPT output Pin) for the laser to always start in the OFF state.
I am not sure what is causing your edge bands but I suspect it relates to the above where the software switches the laser OFF at the start and end of each line and with your active High set-up this turns the laser ON.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.