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This section is for questions and advanced guides for BoXZY's laser head.

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Getting initial LASER focus correct

I was part of the initial Kickstarter group and have had my BoXZY for about 6 months but have only just unboxed it as I was in the throes of rebuilding my workspace for precision stuff.

I have never used a CNC device before but have managed to get the software installed and following the guides have gotten the LASER engraver working. (It seemed to me the simplest device to get going first.) The problem is, I am not sure how to measure the proper distance from LASER to work to properly focus the beam. As a result the spot is greatly elongated in the Y-axis. This means vertical strokes (movement along Y) burn well but horizontal strokes (movement along the X-axis) do not. Edges are not sharp either.

Questions:

  1. When BoXZY is homed (X=0, Y=0, Z=0) what is the distance from LASER aperture to the work surface for the purpose of accommodating material thickness?
  2. I have tried several different distances from LASER aperture to work surface and I can't seem to get the spot small and round. Is it possible there is a problem in the LASER optics? If so, how to be sure and how to correct?

Thank you in advance for your help.

Brian Lloyd

Update (12/16/2016)

So, if I understand you correctly, if I move the work surface to Z=50.7mm then the LASER should be focused in the surface of the leveling plate? (Confirm: the leveling plate is the three-point magnetic plate that attaches to the three leveling screws magnetically?) In that case, if I put some 10mm-thick material on the leveling plate, set Z=60.7, the LASER should be focused on the surface of the material and if it is not, the focus collar on the LASER aperture should be adjusted to bring the beam into sharp focus?

Apparently there is some other software I am apparently not using because I don't see any "Alignment ON" button in Repetier-Host Mac. So this brings up three new questions:

  1. Besides Repetier-Host Mac, Inkscape, and thlaser-inkscape-plugin-boxzy, what other software do I need to load?
  2. Different materials are going to require different amounts of energy to properly etch. I have tried wood and black-anodized Aluminum. It etches the wood but not the anodized Al. I suspect that the feed-rate/step-rate needs to be a lot slower for the anodized-Al to etch so that more energy is delivered to the surface. Where do I set that?
  3. Is all this information written down in one place? I tried to follow the guides but must have missed something.

(Oh, so many questions now, like whether I should be running this on a BBB or RPi under Linux instead of the Mac Server that runs most of my network.)

Thank you again.

Brian

Answered! View the answer I have this problem too

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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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Hi Brian,

This will be fairly simple to get resolved for you. First, based on what you said, it sounds like your platform is not level. As a note, the lasers are factory set to run on the metal leveling platform. It is very important to first level that platform or the focus will fade as the platform goes downward or upward relative to the level position.

The second issue will be overall focus. First please make sure nothing is blocking the lens. The lasers were focused to the 50.7mm position with the leveling plate installed. The interface will move the platform to the correct focal position when you enter your material thickness and press the focus button inside the BoXZY tab of the interface. However, the Kickstarter machines were not always focused properly based on variations in the Z limit height as changes were made in production. So it's not impossible your laser will not be properly focused when you use the focus button. This is very easy to remedy. To focus the laser, press the focus button on the interface so the platform drops to the correct position and install your leveling platform. Then hit the "alignment ON" button. This will turn the laser on at very low (laser pointer level) power. Then turn the small black protruding cylinder at the bottom of the laser canister watching as the beam widens or shrinks (careful not to rotate too far the wrong direction or it will unscrew completely). If the beam begins to widen, turn the opposite direction until the beam is at its smallest diameter. If it narrows, continue rotating until the laser reaches its finest diameter. Rotate it back and forth a little at that point to find the smallest point possible. Then turn the alignment feature OFF. This will focus your laser for your machine and the correct Z height position.

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Thank you Just. (Odd name, Just Helping.) ;-)

I realized when you started talking about non-existent options that it was probably a software difference. The current Getting-Started doc branches off to Mac before anything tells you, "But you will want to get everything set up under Windows first because a lot of the options don't exist in the Mac version." So I managed to get windows going on my laptop, went through the setup for Windows, and everything came out just right. My "Hello World" (literally "Hello World" with an oval around it) came out quite nicely when run from the Windows software. Too bad I don't have a Windows machine to dedicate to running BoXZY. I was planning to dedicate a BBB or RPi but it looks like Linux is not well supported.

Did you guys every think of just writing the program in Java and then it would run on nearly any platform? I have had excellent results that way.

Is there a list of the G-codes for running the LASER? For that matter, is there a list of G-codes that BoXZY understands? At least I could hand-edit the G-code output.

I did try etching my "Hello World" onto black-anodized aluminum. No effect. So I am guessing I am just not delivering enough energy to the spot. I tried changing the speed and LASER power level from the BoXZY tab (under the PRINT button) but no effect. Rate and power level appeared to remain unchanged. Is there a trick?

So when is the 100W CO2 LASER head going to be ready?

I know that all material is different and color determines how much of the power is reflected, but I suspect that it is possible to figure out "ballpark" numbers for common materials and colors, and maybe identify more, "don't even try with this." Just thinking aloud.

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Hi @brian

I'm on the road at the moment and won't be near a true computer for a couple days, but I have a link for the Gcode list you wanted. If you scroll through the whole things there's lots of great information. I'll provide a more complete reply once I have a human size keys to type with.

List of G-Codes supported by Boxzy

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Haha, I love this name. I promise it's "Just Helping" because I'm just here to help, free of any ego. No secret implication intended.

BoXZY's interface was created on a pre-existing architecture, it wasn't built from scratch, unfortunately. However, when the new interface is released it will be capable of working across all platforms. I image it's likely still pretty far out.

My trick with Anodizing probably isn't the best idea, but it works for me. So, this is not a suggestion, just raw information about what I do: I adjust the aperture live at full power during the first engraving over a scrap anodized piece of aluminum until it starts marking. It's finicky, but once you've locked it in, it keeps working if you don't change anything and the scrap material is the same thickness.

I wish so very deeply BoXZY could receive a 100W C02. But you may see a 25-40W BoXZY one day.

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I believe for most materials, full power, full speed is the best way to start out and gives the best general results. Really the only thing shouldn't do is a full power, very low speed run on an easily flammable material. Or a known poisonous plastic. Some people still do it, but hey, as long as they build in great ventilation and have a fire extinguisher, more power to them. Still, it won't be very long until there's a don't even try this list, as you suggested.

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Brian Lloyd will be eternally grateful.
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