Need some help? Check out our new Help Centre

Engraving Images Using TTL (pulsing)

edited December 2014 in PicEngrave
Some materials and images do not engrave very well using varied intensity. Wood that has allot of grains or is too dark to get decent shaded results, must be done the old fashion way that the Commercial CO2 laser engraving machines still do today. They have to convert the image to 1bit Black and White and then pulse the laser with dots to get the allusion of shades.

We picked up a cheap Cigar Box at a yard sale and the wood is a little dark, so we are going to explain how to TTL engrave an image on it with the EmBlaser.

First to insure there are only Black & White in the image, we needed to Dither it first. In the PEP5 image editor there are 11 different Dithering Algorithms to choose from. PicEdit Lite also has this Dithering feature. We are going to use Atkinson on a Clipart image that we decided to use on this Cigar Box.

After re-sizing the image and Dithering it, we loaded it into PEP5 to generate the gcode. Since we only want zero power or full power for pulsing, we set Min at S0 and Max at S255. If the image is not 1bit, the Gcode PicEngrave Pro 5 or PicLaser Lite generates will have power variations in between the S0 and S255 values, so the image Dithering process is very important. We don't know what this wood is or how it will burn, so we set the Feed Rate at 60IPM (1524mm/min).

After starting this engraving I realized, we could have increased the the Feed Rate more, or lowered the Max power as it's burning the image a little dark. You can experiment with the different Dithering Algorithms, max power setting and Feed Rate to achieve the desired result on the different materials you choose.

The Gcode file was 1,466,683 lines long and we streamed it to the EmBlaser with PicSender.

PEP5

DSC00037

Comments

  • This seems like the method I need for what I do since I'm used to the way Co2 lasers do it. I'm glad I read this!
  • If you have any questions, we are here to help.
  • I've got the app running now but I was wondering if you could post a screenshot of example settings within PEP5? All the artwork I use on my products are already made in only black and white so no dithering is needed.

    Thanks!
  • edited March 2015
    This is screenshots of PLL & PEP5 settings. I am only guessing at the feedrate and max laser power level, so you may have to adjust from there. 0 is no power and 255 is full power. I used a .254 Pixel Resolution which is the step over and step ahead gcode movements.

    Providing your image is pure white and black, the laser control power in the gcode, will only go from your Min & Max settings and nothing in-between.

    This .254 PR is the default setting the way it calculates and engraves the size of the image. If set at this value, the image will be engraved as the original size when opened in the programs. If you need to reduce the Pixel Resolution based on the lasers burn line width, the image editor in PEP5 and our PicEdit Lite program has an Auto sizing feature based on the Pixel Resolution you will be using. This also can be done by re-sampling the image's pixel size in an image editor from a scaled calculation.

    If using PEP5 and you have allot of white areas around the border of your images, there is a Skip White Background feature the will not generate codes or movement there to save on engraving time. It will not skip whites if there inside of the black areas.

    You can raster engrave Horizontally, Vertically or at a 45 degree angle in both programs.

    With PLL, the gcode is generated for X&Y zero at the bottom left corner and engraves up and to the right from there.

    PEP5 gives the option of bottom left corner or center in the image. You can also set X & Y offsets.

    Capture5

    Capture4
  • Thank you so much for this! Now I have a baseline to experiment from which is extremely useful to me.

    Thanks again!
  • If you call this mode TTL, why do you have Analog/PWM mode selected?
  • edited March 2015
    The gcode format generated by that mode may be better and faster for many TTL projects than the TTL Laser mode, which may execute slower. Test both modes for your projects and use the one that gives you the best results.
    John
  • I'm testing but I simply cannot get anything to happen. The machine moves, extremely slowly but no laser action at all. I've copied the settings from the screenshot perfectly. I have no experience with PicSender so maybe i'm doing something wrong there?
  • In PicSender select GRBL PWM code, Send M03, Position Sent and Metric.

    Also grbl processes movement smoother and faster when X, Y commands are changing on every line, so try the 45 degree angle.

    To add to John's comment, TTL is a mode of just having either on or off (pulsing) of the laser, but with the EmBlaser, it uses PWM also and the Analog/PWM option has Skip White Background where the TTL option does not have. Looking at the type of images you are using is why I chose to use that option.

    I'm not sure why your not getting any lase action other then it's running in white areas. It should be going to full lase power in black areas. (S255)

    Another reason could be, since PicSender in Demo mode will skip lines and it may be skipping the line with the M03 command. Open the gcode file in a text editor and look for the M03 at the beginning of the file. Copy all the commands on that line and paste it to a new line before or after that line. By doubling those commands, if PicSender is skipping one, it will not skip the other.
  • I used PicEngrave Lite and got something working. I'll have to experiment further.

    You mention that PicSender skips lines in demo mode, does that explain why there's gaps between the lines when it's rastering?
  • Yes, it will cause gaps because of skipped gcode lines. It's the demo restriction and is stated on the PicSender page on our web site right below the "Demo Download Table".

    http://picengrave.com/PicSender.htm

    Also the gaps could be caused by the Pixel Resolution used. If the step over is larger then the laser's burn line width, there will be un-burnt lines between them.
  • Okay this is all making a lot more sense to me now. I'm gonna purchase a license for PicSender later today and I think I'll get results I need once I've experimented properly.

    Thanks so much for quick responses and very good explanation!
  • I just purchased PicSender so I'll be experimenting tomorrow with the laser!
  • Thank you. Look for your registration in your inbox. After registering and connecting to the com port, select the yellow grbl button. In there, you can save all your grbl settings for backup in a text file.

    If you have anymore questions, let me know.
  • Thanks! I also purchased the PicEditor. I think PicEngrave Lite will do fine for me.

    I'm about to set up a template where I put the outlines of the enclosures I engrave on black acrylic baseplate. I will then use that template to align the enclosures, and put artwork inside the outlines to get perfect alignment for 8 enclosures at a time.

    Do you have any tips or ideas to get the best results?

    My idea is to use Inkscape (which I normally use) to set up the template with the outlines and engrave that on the acrylic. The document I'll use is 420x280mm (A3 size) so that it's always consistent as well.

    Is there a format or method to export the template that will give me the maximum resolution? I will need this to be as sharp as the laser can possibly handle.

    Cheers!
  • edited March 2015
    Give me some time on how the best way would be to approach multiple engravings. I don't think a G91 incremental position move can be use with the EB grbl, but I may be wrong.
  • Oh and to be clear, with the template, each enclosure will have the same artwork. So it's basically the same thing spread out as 8 copies over the 420x287 workspace. There's no gradients or anything, just black and white.
  • Production! I totally understand. :-)
  • Sweet, thanks! The idea with the template is to be able to use it to just fill in the artwork I need and the baseplate will always be in the same spot so the template and enclosure location shouldn't vary all and stay constant. Does that make sense?
  • Yes, that makes sense. I just have to figure out how to offset the zero in different places. PicEngrave Pro 5 as the ability to set the offsets and the gcodes could be combined together into one file just by copying and pasting after generating 8 different gcode files with different offsets. PicLaser Lite does not have that option, so that is why I would need some time to figure out how to approach this.
  • That does sound like a good idea and possibly easier as well! Would you recommend doing that?
  • That would be easier, but let me see if I can come up with something first using PicLaser Lite.
  • I'm exporting a file from Inkscape at 300dpi, black artwork on white background but when I import that into PicEdit and change any setting, the whole thing turns black. Why would that be? When I open the image in PicEdit, it shows it fine, until I change any setting except for resizing.
  • edited March 2015
    I'm not sure why it would do what your experiencing. Can you send your image you used, or a just a test image this happens with to the email address your registration was sent so we can test this here?

    After doing some research, I believe I have a plan on offsetting your gcodes
    from PicLaser Lite for your image engravings, but still have to work out the details and test it here on our EmBlaser.
  • I figured out the problem and it was because the image had a transparent background so when I made sure it was black on white, it worked fine. I'm still just testing on cardboard before testing on enclosures and I'm getting some good results now.

    I went for PicEngrave Pro again and realised I didn't change the Z axis to S and that's why it wasn't working before. It's working now!
Sign In or Register to comment.