Page 11 of 16 FirstFirst ... 789101112131415 ... LastLast
Results 101 to 110 of 153

Thread: CNC Laser Engraving 8bit Shades of Grey 445nm

  1. #101
    Join Date
    Jun 2013
    Location
    Florida
    Posts
    82

    Default

    The analog voltage out from the encoder is linear in either direction of rotation.

    A easier solution is to use an Arduino UNO R3 and a gshield stepper driver. With the J-Tech PWM grbl hex download on our forum, it will output a 0-5v PWM signal on pin 11 for the modulation using S value commands from 0-255 in the Gcode.

    http://www.picengrave.com/forum/inde...7d35442a7a0a51

    That is what we are using for our Shapeoko and the J-Tech Laser now.

    Extensively Re-worked/Re-designed/Modified Servo K2CNC KG-3925, Mini Diode Laser Engraver and now a Shapeoko 2 Laser Diode Engraver.

    https://www.picengrave.com

  2. #102
    Join Date
    Jun 2013
    Location
    Florida
    Posts
    82

    Default

    We have been experimenting with 3D Laser Diode engraving using our EmBlaser. We made an air assist for it and it helped considerably with the precision depths of cuts.

    Here is the image we used to generate the gcode in PicEngrave Pro 5.

    Click image for larger version. 

Name:	3D.bmp 
Views:	19 
Size:	853.8 KB 
ID:	47469

    Here are the results on Poplar.

    Click image for larger version. 

Name:	3D10.jpg 
Views:	30 
Size:	486.0 KB 
ID:	47470

    Click image for larger version. 

Name:	3D11.jpg 
Views:	37 
Size:	410.3 KB 
ID:	47471

    Here is a perspective of the 3D engraving.

    Extensively Re-worked/Re-designed/Modified Servo K2CNC KG-3925, Mini Diode Laser Engraver and now a Shapeoko 2 Laser Diode Engraver.

    https://www.picengrave.com

  3. #103
    Join Date
    May 2008
    Location
    Westlake, OH
    Posts
    122

    Default

    On the gray scale using a digital pot. What is driving the signal to the digital POT? A Arduino based controller? or PI? or something you have no control over? Because you can drive the Analog or TTL modulation directly from a "Analog" pin on the processor without all this circuitry. You will want to make a calibration table because the power gain in these diodes are not linear, but a $10 Arduino could do this with a resistor directly if any need at all. Assuming you are using a Driver like a FlexMod 3


    Quote Originally Posted by JJWMACHINECO View Post
    Thank you,

    To answer both of your questions, the last two engravings are 7.5” X 9.5” and running with a stepover of .007” at 50IPM and took about 3 hours and 15 minutes to engrave. I’m in process on another build with dual 2.5W 445nm diodes that will speed the engraving process up considerably. Your correct, it’s not really shades of grey because of the color of the Birch Ply, but with my setup I have 256 levels of power from wood color to burnt dark. I use a US Digital MA3 10bit analog shaft encoder that outputs 0-5V for the analog modulation to the driver in a 360 degree rotation. In my image to gcode program, it interprets the image into 256 .0001” Z axis moves (depths of cut) which my encoder is tied by a timing belt to the Z axis.

    There is another electronic means using a DAC that takes the step and direction pins from Mach3 to get the 256 steps (power levels) also. Here is a PDF that was written by the author of the program I use and explains in more detail how it is done. More information about my setup is in this PDF also.

    http://picengrave.com/Laser%20Setups.pdf

    John, the author of Picengrave Pro is in process of building a laser diode engraver using an X&Y stage from lightobject.com. He will be using a Max5451 digital potentiometer for the 256 power levels. His program lets you select A,B,C or Z axis for the Gcode generation to control the laser diode's power levels.

    I have looked at a 405nm, but what I have read, the 445nm's have more wattage and durability. My laser diode engraver mounted on a CNC router has over 800 hours on it with no failures.

    Here is a video of my mini laser engraver in action. If you watch the 0-5V analog volt meter, the voltage goes up and down with the power of the laser diode.

    Jeff

    Rob Mudryk
    Retired old and Grumpy Laserist

  4. #104
    Join Date
    Jun 2013
    Location
    Florida
    Posts
    82

    Default

    Quote Originally Posted by rMuD View Post
    On the gray scale using a digital pot. What is driving the signal to the digital POT? A Arduino based controller? or PI? or something you have no control over? Because you can drive the Analog or TTL modulation directly from a "Analog" pin on the processor without all this circuitry. You will want to make a calibration table because the power gain in these diodes are not linear, but a $10 Arduino could do this with a resistor directly if any need at all. Assuming you are using a Driver like a FlexMod 3
    Hi Rob,

    We use three different means to vary the intensity of the laser. First is a MA3 analog magnetic shaft encoder driven with a stepper motor and Z,A,B or C gcode commands based on shades in an image which outputs analog 0-5v to a Flexmod. Second is a DAC circuit that takes the step & direction signals from a CNC control software like Mach3 & Z,A,B or C axis gcode commands based on shades in an image which outputs analog 0-5v to a flexmod. Third is we use a real $35 Arduino UNO R3 and S0-S255 gcode commands based on shades in an image and output a 0-5v PWM signal from Pin 11 to a Flexmod or J-Tech TTL/PWM driver.

    Try your method using an "analog" pin on a processor and post here.
    Extensively Re-worked/Re-designed/Modified Servo K2CNC KG-3925, Mini Diode Laser Engraver and now a Shapeoko 2 Laser Diode Engraver.

    https://www.picengrave.com

  5. #105
    Join Date
    May 2008
    Location
    Westlake, OH
    Posts
    122

    Default

    I am wondering about what controls the type one and two. I am assuming this is based on the operators/designers level of comfort with mechanical or electrical, or programming I was wondering in the wheel version, what is converting the code to stepper motor. Because if you had access to the firmware the third type of z axis mod could be skipped... You are taking digital -> analog -> digital -> analog to flexmod. Also the flexmod and any diode the gain curve is not linear, in your software or can do in the arduino firmware a grayscale attenuation map should be creates. 90% of the gain is in the first 50% input voltage of the Flexmod, but there is a threshold starting at 6-7% This can be done with a 16 step gray scale bar, or a power meter for example.


    Quote Originally Posted by JJWMACHINECO View Post
    Hi Rob,

    We use three different means to vary the intensity of the laser. First is a MA3 analog magnetic shaft encoder driven with a stepper motor and Z,A,B or C gcode commands based on shades in an image which outputs analog 0-5v to a Flexmod. Second is a DAC circuit that takes the step & direction signals from a CNC control software like Mach3 & Z,A,B or C axis gcode commands based on shades in an image which outputs analog 0-5v to a flexmod. Third is we use a real $35 Arduino UNO R3 and S0-S255 gcode commands based on shades in an image and output a 0-5v PWM signal from Pin 11 to a Flexmod or J-Tech TTL/PWM driver.

    Try your method using an "analog" pin on a processor and post here.
    Rob Mudryk
    Retired old and Grumpy Laserist

  6. #106
    Join Date
    Oct 2012
    Location
    Germany
    Posts
    1,478

    Default

    ... I'm avoiding analogue driving of lasers without a calibration-curve ... and mostly even then - it's simply not precise enough ...

    My engraving lasers are all driven with pulsing -- from 1W/2W diodes up to 120W CW fiber-lasers ;-)

    Viktor

  7. #107
    Join Date
    Jun 2013
    Location
    Florida
    Posts
    82

    Default

    Quote Originally Posted by VDX View Post
    ... I'm avoiding analogue driving of lasers without a calibration-curve ... and mostly even then - it's simply not precise enough ...

    My engraving lasers are all driven with pulsing -- from 1W/2W diodes up to 120W CW fiber-lasers ;-)

    Viktor
    Try 3D engraving with your Laser Diode engraver. Is it precise enough?
    Extensively Re-worked/Re-designed/Modified Servo K2CNC KG-3925, Mini Diode Laser Engraver and now a Shapeoko 2 Laser Diode Engraver.

    https://www.picengrave.com

  8. #108
    Join Date
    Jun 2013
    Location
    Florida
    Posts
    82

    Default

    Quote Originally Posted by rMuD View Post
    I am wondering about what controls the type one and two. I am assuming this is based on the operators/designers level of comfort with mechanical or electrical, or programming I was wondering in the wheel version, what is converting the code to stepper motor. Because if you had access to the firmware the third type of z axis mod could be skipped... You are taking digital -> analog -> digital -> analog to flexmod. Also the flexmod and any diode the gain curve is not linear, in your software or can do in the arduino firmware a grayscale attenuation map should be creates. 90% of the gain is in the first 50% input voltage of the Flexmod, but there is a threshold starting at 6-7% This can be done with a 16 step gray scale bar, or a power meter for example.
    We can adjust for any power curve there may be by adjusting the Feed Rate Change (variable feedrate) percentage in our software when we generate the gcode from an image.
    Extensively Re-worked/Re-designed/Modified Servo K2CNC KG-3925, Mini Diode Laser Engraver and now a Shapeoko 2 Laser Diode Engraver.

    https://www.picengrave.com

  9. #109
    Join Date
    Oct 2012
    Location
    Germany
    Posts
    1,478

    Default

    Quote Originally Posted by JJWMACHINECO View Post
    Try 3D engraving with your Laser Diode engraver. Is it precise enough?
    ... yes it is -- I'm actually developing a laser-engraving application for printing plates, but this is under NDA, so no images to post, sorry.

    But will try this on my own with another machine+controller I'm actually reactivating, so can test with the 445nm-diodemodules and with the fiber-lasers ... but this can take a while ...

    Viktor

  10. #110
    Join Date
    Jun 2013
    Location
    Florida
    Posts
    82

    Default

    Quote Originally Posted by VDX View Post
    ... yes it is -- I'm actually developing a laser-engraving application for printing plates, but this is under NDA, so no images to post, sorry.

    But will try this on my own with another machine+controller I'm actually reactivating, so can test with the 445nm-diodemodules and with the fiber-lasers ... but this can take a while ...

    Viktor
    Will printing plates be 2.5D (flat top) or 3D (full contour)? Yea, I can't post all our experimenting information either because of the few NDA I have also, so I do understand.
    Extensively Re-worked/Re-designed/Modified Servo K2CNC KG-3925, Mini Diode Laser Engraver and now a Shapeoko 2 Laser Diode Engraver.

    https://www.picengrave.com

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •