Engraving on Birch Plywood

I have been trying to get a photo engraved for a customer and not having any luck at all. I have looked on forums ans user groups , tried settings from A to Z and all in between. The photo (below) is the one that they want but the contrast is not so good. I have done everything I could think of. Any help would be greatly appreciated.

Doug

[https://hosting.photobucket.com/images/ii554/Doug_Farish/Barnes-02(1).jpg https://hosting.photobucket.com/images/ii554/Doug_Farish/Barnes-01(1).jpg](https://hosting.photobucket.com/images/ii554/Doug_Farish/Barnes-02(1).jpg https://hosting.photobucket.com/images/ii554/Doug_Farish/Barnes-01(1).jpg)

You need to tell us what your laser is including power and the settings you are currently using to burn the picture. Are you using a dither pattern?

I have a Ortur LU1-4 20watt. I have tried grayscale and Jarvis mostly. My speed has been between 1000 and 4000, power from 35 to 75. Not sure where I’m going wrong. I guess that I am not understanding how to use the grayscale test that I burned with the max and min power settings. I’m not used to tying to engrave a photo on Birch plywood.

Thanks,
Doug

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Sand the Birch plywood to 120 grit, blow off the dust. Set it in the machine and focus the laser using your focus cylinder.

Set the dither to Jarvis. Set the speed between 1000 and 3500. Set the power to 100%. Overscanning at 2.5%. Line Interval between .06 and .1. Scan angle at 0 or 90 depending if you want side to side or up and down travel of the laser. Usually keep the number of passes to 1.

Speed and line interval will determine how long the burn takes. 100% power is max power and it will vary up to 100% making for darker burns.

Make tests by reducing the picture to something like 2"x2" so it goes quick and you can evaluate the quality of the burn.

Just so you know, Maple plywood works better.

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Thank you. I will give that a try. I just do not want to use 100% power. The image is going on a 14" round for a door hanger. I will look at different rounds to see what I can get.

Doug

You should use a photo editor and mess with the contrasts to make a good image first, and to burn it a bit darker, you can use the Baking Soda method.

It takes trial and error. You shouldn’t be too afraid to use full power on a diode, just don’t run it at 100% for hours on end. 100% power will save you a few hours on big jobs.

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Will give that a try also.

Thanks,
Doug

I agree with some of the above. I would not use Greyscale unless you have mastered it…you should be able to get a good result with a dither like Stucki or Jarvis. Also Birch is not going to natively burn as dark as other woods like maple as mentioned. Alder is perfect as can be beech but not easily found in plywood. I avoid birch ply for any photo although I need to test the baking soda.
The photo has some issues that will challenge you. The mans shirt is white with little contrast so getting that to come out decent will be a challenge without ending up making other areas possibly too dark. It is really a learned artform to adjust a photo in say Photoshop etc to get the light levels correct as well as contrast. Usually when you nail the settings that will burn the best the photo will not look great on the computer. So what looks killer on your screen usually looks like crud when burned for most photo’s. Edit in Photoshop or whatever you have and work in greyscale so change the color mode…do not try and adjust a photo for laser engraving while its still in color. It is easier to get contrast correct if you make the photo black and white.
Some people like to then convert the photo to bitmap which will diffuse dither it before sending it to the laser. I personally do not as a previously dithered or bitmap can’t be tweaked in lightburn much. However…I will convert it to bitmap quickly to see the dithering effect as it will change the contrast greatly. If it is not what I like I Undo the bitmap (which goes back to greyscale) make adjustments then convert to bitmap and dither it. I go back and forth until it looks close to what I want as a bitmap. Then I undo the bitmap one last time and save as a greyscale jpeg. Then in Lightburn I use the adjust image (rt click menu) and choose my dither…zoom in so you can see the actual dithering and make final gama, brightness and contrast adjustments. If it doesn’t look good dithered, in the lightburn adjust image screen, it won’t look good on wood.
I would consider using an oval crop tool and get rid of most of the clothing and concentrate on the faces with maybe keeping some of the upper body but me…I would crop most of that out. It just won’t burn well. You have to edit out what just won’t work.

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That is a great reply. I think I have got it figured out. Here is a pic of what I got. I need to tweak it a bit more but I like the results.

Thanks again for all the help,
Doug

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Wow that is a huge improvement I am impressed….really. Very very good job :ok_hand::ok_hand::ok_hand::ok_hand:

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Thanks. I could not have done it without everyone’s help.

Doug

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So what were the settings you ended up using?

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I hate to sound like a traitor but I used Laser GRBL to get the settings and used Scott’s advise to fine tune them. I’m still trying to get LightBurn to do the same thing. I went back to do another burn with Laser GRBL and I lost the settings I used, forgot to save the file, so I redoing it right know.

Doug

I will add…although I rarely dither final in photoshop do not be put off by trying that…meaning convert to a good looking bitmap with diffuse dither at maybe 300 DPI ( your call) save it. Import to LB and run in pass through mode (no dithering ) and see what it looks like. Hey…there are guys who absolutely nail it this way. You just won’t be able to adjust gamma and contrast I think. Once you get your dithering down whether in PS or LB you will have the eye for it moving forward

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what settings did you use and what machine?

This method has produced great results for me. It’s a technique (using Photoshop) developed by Rodney Gold:
Convert to 8 bit greyscale (Image | Mode | greyscale)
Resize the image to the desired final size size at 150–300 ppi (Image | Image Size)
Increase contrast and brightness ~25 ensuring that it is not median gray (Image | Adjustments | Brightness-Contrast)
Unsharp mask at 500% w/ a radius of 3–5 pixels, Threshold 0 (this will exaggerate edges radically — if need be, repeat at 150%, 1pixel and 0 threshold) (Filter | Sharpen | Unsharp mask)
Convert to a bitmap using 125–150ppi using Diffusion pattern. (Image | Mode/bitmap)

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I never thought of using a bitmap image. I do work in PS. Are you calling PPI the same as DPI? just wondering.

Thanks Doug

What speed and power would you use John? I have a LU1-4 20 watt.

Doug

PPI, LPI and DPI are functionally interchangeable unless you get into specialised equipment.

PPI (points per inch) is used for machines that generate single points that are not necessarily aligned in a grid. For example the printing used in print where you have points of different sizes (newspaper, comics).

LPI (lines per inch) is used for machines that have discrete steps in one direction (usually rows) but are either analog in the other direction or very hires. For example CRT televisions and laser engravers (where the density of lines a picture is engraved with is given in LPI but each line has a completely independent and maybe even higher resolution that’s determined by the speed the laser (or electron tube) can be switched on and off).

DPI is used when dots are arranged in a fixed grid, like on a computer monitor.

PPI (pixels per inch) as a synonym for DPI. And DPI is sometimes used to mean PPI. Some issue with different industries having different existing terminologies when going digital…

Thank you for the answer. I thought that was what it meant.

Doug

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