Second project completed. 😄

My second project has now been completed. The images were all .svg files that I had to convert to jpeg files before Luban would accept them. The power was set at 60% and the lesson I take away from this set of example images is that the constant power setting does not mean that each image will be produced with constant results.

I cannot begin to understand why some of the images do not look as they were engraved by the laser beam at its 60% power setting. They may have been etched on different days so possibly the atmospheric conditions may have affected the images.

The image on the bottom left looks to be the one which has taken the laser beam the most easily. The next 3 along the bottom row look to be even for power and etching similarity. The second image on the middle row looks to be quite light in comparison to the other images on that row. The middle two on the top row also seem to be a little lacking in power. Maybe the wood was made of very different quality. Possibly dampness has crept into the wood store.

How and ever, here are 12 coasters made from laser cut plywood that is 2mm thick. Any suggestions as to how to keep the applied power of the laser at the chosen setting would be helpful.

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They are different images, so it’s hard to say? If the saturation of the image is generally lower, 60% will be lighter than a darker saturation at 60% I think

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Thanks for your thoughts, Ian. I take a monochrome .svg image (only black or white, no greys) and convert it to a jpeg file to take into Luban. The bits that are black stay black and the bits that are not black (white) stay white. The conversion process from .svg to .jpeg does nothing to change the black or white tone which is assigned to each pixel. I processed these images in Luban as black and white images.

The way I would have expected the images to be rendered by the laser was where there were black pixels the laser would switch itself on and burn the pixel into the wood and where there were white pixels, the laser would switch itself off. The technique is redolent of old newsprint where the paper was black and white and images gave an impression of being comprised of many shades of grey. I have attached a couple of example halftone images so that you can see that the switched on pixels are black (varied sizes of black) to give a grey tone and the switched off pixels remain white.

Technically speaking, I had expected the power setting to work the same for every image because the non black or white tones you can see in the images are purely an optical illusion caused by spacing the dots of ink further apart and making them smaller at the same time. I am not yet sure how the laser beam is handling that. i can see that it will be able to burn sections of the wood which are further apart. What it cannot do is make the burnt area smaller than its resolution. I guess this where software which can vary the power of the laser would be helpful too.

I have no idea how or whether it would be possible to translate say… 18% grey (precisely midway between full black and full white) to 50% laser power. It is an interesting problem and my thought about this issue is that it will only be solved by the software engineers.

halftone eye

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Hmm, it looks like you went with the greyscale processing mode in Luban. And that would affect the contrast and could be the reason why the final results vary.

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Thanks JKC20. No I did not use greyscale processing for those images. After I had converted the .svg images to .jpeg files, I processed them as a black and white images, thinking that would provide the most contrast.