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Original post by: Just Helping ,

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You're exactly right. I was referring to the 3 point magnetic platform and if you move to 50.7 in the Z that would be the factory focal length onto that platform. Add your material thickness to that number, so 10mm material thickness would leave you with 60.7 focal point. It is definitely easiest to fine tune the laser focus with the black aperture. I'm not sure it would be possible to tune the focus of the laser that finely by moving the cylinder up and down inside the quick change gantry, though I've never tried. The focal depth for the laser is somewhere around 2mm. The laser power drops of extremely quickly outside of the focal range.

I wasn't aware you were using Repeater Host Mac when I wrote my earlier response. The alignment feature is specific to the Windows interface. As you are creating the laser file through Inkscape and running it in Rep Host, you will be doing any offset positioning manually with g-code (The windows interface has powerful image rastering capability and alignment features, but using Inkscape allows the use of vector files and better dimensional control, just for reference). So in order for you to re-focus your laser, the best way I know of off hand would be to move the Z platform into position and run a very low power cut line. Say {G1 X100 F200 L11}, this should give you plenty of time to focus the laser as the axis will move very slowly (this is how I initially focused my laser prior to the update that added the alignment mode). Be careful not to accidentally enter L100 (full power) if you do this and consider that the machine will be moving as you reach in, albeit very slowly. So please ignore me if you don't feel like this can be done safely. There is a command to turn the laser on and off at low power when stationary, but I will not be able to find out what it is until Monday or Tuesday. If you'd be nervous about my proposed approach I will find out about that code for you.

As far as speeds and power levels, there is not one comprehensive list of recommendations for each material at this point. It would likely be a difficult undertaking as speed and power level is used to adjust both shade and depth of the etch, and it depends on what you're trying to accomplish. Each color of material, even the same material, engraves differently. As an example, some of the images I've done look great when done with high power and a deep etch, some only engrave correctly and show detail with low power and a very light etch. There are times my settings will work one one piece of wood, and I have to adjust it for another piece of the same type of wood when the color or shade has changed.

If you would like to anodize aluminum your laser focus will need to be as flawless as possible, dead center of the focal depth. In my experience the laser will mark anodizing at full speed and 100% power, and the lines will darken as you slow down, but only to a point. So personally I would start with 50% speed and 100% power if I was trying to get everything locked in. Just to add some more notes; it's important to keep in mind the laser focal point is only 0.1mm, so a single line may not be easily visible while an image may still be highly visible. As for colors of anodizing, it will not mark clear or anything lightly colored. Being a visible spectrum laser it will refract off of lighter colors. My best results have been on blue and black anodizing.

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