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Improve accuracy / sharpness

I want to improve the sharpness of my engravings for the products I make.

Some turn out great with the same settings but this particular one is a bit hard to get perfect.

I'm engraving with PicEngrave and PicSender using 2000mm/min and power of 120 on the left and 90 on the right. The left one has feeders change of 20% which I feel makes it a little worse with fine stuff since the laser is either on or off.

Is it just a matter of slowing it down considerably to get it sharper?

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Comments

  • Are you dithering the image first, or using a color or grayscale image when generating the gcode?
  • It's a dithered image. Here's an example that was done with an Epilog laser with the same file, except this one has a slimmer don't actually. I swapped for a bolder one because of this.
    image.jpg 4.8M
  • Can you post an image with the Emblaser result so we can do a comparison?

    If you want to get sharper results then vector engraving is the usual way to do this. You image may not be suitable for this though, but could be worth considering.

    This would mean converting your image into a vector drawing and using cross hatching to fill in the areas.

    This would give you a different look though.

  • edited April 2015
    I was able to get very sharp results TTL raster engraving with the dithered generator image even running at max feedrate with full power (255) in Black areas. The Min was set at zero for white.

    http://forum.darklylabs.com/index.php?p=/discussion/241/free-picfrc-licenses-given-away#latest

    You may need to increase your DPI in the image, sharpen it more and experiment with a different Dithering Algorithm in the PEP5 editor. I get the best results with the Atkinson Algorithm because it's adjustable.
  • Here's another test with a lot less speed and a bit less power. See how the laser still kinda cuts the font? The image is black on white and the font is solid white. I have the max power set at 80 and min at 0 but it's still engraving when it shouldn't.
    image.jpg 1.2M
  • I tried a horizontal engraving with pretty much the same settings. Why does it look like this?
    image.jpg 1.1M
  • I will Jeff get into more specifics on this with respect to the picengrave programs, but it definitely looks like a resolution issue.

    Increasing the DPI will mean the lines will be closer together and also the edges of your text will be sharper.
  • It can't be because the black areas are full black with no lines or anything. I export at 300dpi and then use the PicEngrave editor to get it to the correct size.

    I can't use the vector engraving because it's so insanely slow and it does outlines which ruins the engraving. Raster is the method Epilogue uses and all the engraving lines are perfectly aligned to cover the area without any lines between.

    I feel like I'm missing something.

    Could I ask the kind PicEngrave guys to create a PicSender file for me if I provide them the artwork in good resolution?
  • I think it's more about the DPI you are engraving with as opposed to the DPI of the image itself. 300 dpi should be more than enough for the size of engravings you are doing.
  • I feel like there's something that I'm doing wrong
  • I'll tell you here step by step how I end up with the PicSender file.

    I start off with the whole artwork as a vector file in Inkscape, which I then export at 300DPI as a bitmap file. I make sure the background is white and the artwork black. Nothing in between anywhere.

    I put the image in PicEdit and I have to scale the image down considerably so that PicEngrave recognises it and engraves the correct size (physical engraving). If I don't scale it down, it'll try to engrave a massive version of something that's only 66x112mm.

    I don't need to dither the image since it's an export from vector, only containing black and white.

    What am I missing here?
  • This is not a direct solution to your issue, but we have recently had another customer engraving very small and intricate patterns on wooden blocks. They found that securing the lens more firmly helped remove situation where there were very small misalignments occurring. They wrapped a small amount of plumbers tape around the lens threads and screwed it in. It prevented side-to-side lens movement from sudden changes in direction of the laser head. I know Jeff has mentioned placing a drop of hot glue on the lens thread once it has been focused correctly.

  • edited April 2015
    Contact me through the PEP5 registration email with your image attached and I will see what I can do to help you out with it.
  • Email sent!

    Ps. I tried putting some hot glue which makes the lens steadier.
  • Here I did a quick engraving of something exported from Cut2D and everything looks nice and sharp. I had too much power, that's why you see bleeding.
  • Seems like vector engraving is working way better for this specific application.
    image.jpg 1.1M
  • The problem with your image is the DPI when dithering it. The image gets pixelized which caused the overburn in the small text areas. I will work on it for you in Corel Photo Paint in the morning. What Pixel Resolution are you using so I can size it properly?

    With vectors, you will have to engrave slow with less power.
  • Seems like vector is sometime better (top) and sometimes worse (bottom).
    image.jpg 1.5M
  • You have mail. :-)

    Read my instructions when using the image I sent you. Let me know if your engraving sharpness improves.
  • After reading your process again, I noticed you are loading your image into the PEP5 editor and re-sizing it then saving. When it saves, it will not be pure 1bit Black & White.

    Since there are gray shades in the image after saving, PEP5 will not generate the Gcode with just on/off TTL power commands and was the reason the ramping of the laser burn into your text. Pixelization made it worse also.

    After re-sizing, you have to save it, then reopen the saved file, then Dither the image and save it again. Then it will save as 1bit and your Gcode will will only have your min and max power values in the Gcode. You should be able to engrave allot faster with more power and with the Feed Rate Change added. Select Skip White Background also as that will cut down on your engraving time too.
  • Hmm interesting. Your theory sounds right to me so I'll have a go with that. I didn't understand why I would need to dither it since it's black on white to begin with but this sounds right to me.

    I'll get back to you with results. I'm not sure when I can test it though.
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