Lines Per Inch on Anodized Aluminum

Hi Guys,

Quick question here; I just did a test engrave on some anodized aluminum dog tags by BallChain. My settings were 1,000 speed, full power, and 340 lines per inch. When I looked closely at the fully finished tag I noticed my graphic wasn’t as sharp as it looked from a distance. Does increasing the lines per inch fix this problem or is it something else that needs to be done. Thanks in advance. You guys are great.

I run my lpi at 195. I notice I lose definition when I got to higher lpi. Try lowering your settings.


I’ve been using speed 1000, Power 100 and 270 lpi for anodized aluminum with very good results.

I hope this helps.


Aluminum is the one thing I’ve found so far where the higher the LPI you use, the better the results…If you want really crisp, sharp engraves on anodized aluminum…go with 450-675 LPI or even higher. (Problem with the 1335 LPI is the engraving takes so long. Spectacular results though.)


What kind of file was the graphic you used?

I’m in the camp of higher LPI on anondized aluminum as well.

But - you can get really nice results at “regular” LPIs as well. A lot of it depends upon your source image though.


What did you use when you did the pic of Rio on the Macbook?

Source image was 677ppi when I had it scaled how I wanted; print was at 340LPI. I did an “ok” job at isolating him from the background, but not perfect - which led to a small amount of fringing around some of the hairs. Isolating can be tricky (for me, at least) around random hair, unless you really take a lot of time to do it properly.

A couple of the things that can make a huge difference on engraves not looking their best is:

  • low res source image (I try to have the image pixels per inch at 2x the LPI I want to use)
  • JPEG noise/artifacts (these come mostly from saving at low JPEG quality levels, but can also occur in an image that has been saved lots of times). People try to resave as PNG to avoid this, but if the damage has already been done, saving as PNG won’t fix any damage that has already been done.

The noise can often be hardly visible unless you scrutinize an image. It usually appears as “blotches” in the image that are almost white, so they can be difficult to discern. The GF analyzes on a per-pixel basis, so if that pixel isn’t pure white, it’s gojng to get engraved.


I’ll usually take an image into Photoshop and completely remove the background - resave as a PNG.

There’s another trick I’ve learned and it’s quick and very effective - if you have an image that has a lot of noise and you’re not sure you caught it all - after you have removed the background, take the result and add a thick stroke to it using the Layer Style palette - tiny leftover pixels jump out at you and you can easily take a couple of swipes with an eraser to get rid of them.

But your Rio pic is still my favorite engrave on a laptop so far - I didn’t realize the LPI you used was so low…might need to rethink the PPI vs. LPI thing.


It helps that the image is somewhat random on the edges, which serves to camouflage any roughness that may have occurred at the LPI. I also don’t look at my stuff with a microscope :slight_smile: if it feels right and looks right from a normal viewing distance, I’m good. You’ll rarely have a result that looks good from all distances. The distance makes things cohesive. For example, when you sharpen an image for print, you are ideally sharpening it for the expected viewing distance. If the expected viewing distance is 4-6 feet, it will be sharpened differently than an image in a magazine that’s being viewed at ~1/2 arms length. This is a little bit different in the laser world because things respond better if they are oversharpened to a degree, but the principle as a whole still applies.

A lot of people in the print world (regular print) can be really anal about matching resolutions between the input and output so that no interpolation is done and everything matches up perfect. That’s great for benchmark tests but rarely makes a huge, perceptible difference in the real world.

The same with lasering, I try to have about double the pixels per inch as the LPI so that I have sufficient resolution going into it, but if it’s not exactly double, that’s also fine. A little bit of interpolation will occur but it won’t really impact the end product IMO. But, if you have an image that’s 340PPI and you are engraving it at 340LPI, it’s basically scaling the image by 2x. (That’s my story and I’m sticking to it!)


Will do, thanks for the tip. I’m one of those fine detail guys. If it doesn’t look sharp under a magnifying lense I’m not happy with it.

Really! 100 power. Wow I’m doing full power. I’m surprised we could both get decent results. Why do you think this is? Is it your Lpi?

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Hey thanks a lot for the settings. I’m going to try that out as soon as I can. Do you think the rest of my settings are good?

It was a pdf

I see what you mean, that’s almost always a good rule of thumb, the higher you go the crisper it gets. Looking forward to trying it.

Yeah, those are fine.

Also any tips for centering my graphic on the dog tag. I zoomed in and lined it up perfectly using the camera. However when I engraved it, it was off center pretty significantly. Really frustrating and a little unexpected, I was expecting better from the camera and software. Do you think the higher zoom threw me off, should I have aligned it while being more zoomed out?

Yeah, the best way to currently work with something like dog tags (or other objects that you are not cutting out at the same time as engraving them) is to create a jig for it.

There’s a tutorials on setting up jigs here:


::runs in and slides in wearing socks on wood flooring::

PPI/DPI!! Pixels Per Inch - With your raster images, this is SUUUUUPER important. 600dpi is the MINIMUM I use when engraving, because it’s ridiculously high def. You CAN achieve this by shrinking the render space, but you have to beware that your image editing program doesn’t resample the resolution to fit the size.

In the print world, you never ever want less than 300dpi unless you’re working on billboards, but even then… This is why we graphic designers use vector graphics. They scale up and down and recalculate their DPI on demand.

Lines Per Inch - If your DPI/PPI is 240, setting your LPI won’t magically make your 240ppi image a 600dpi rendering! :sob:

I wish it worked magically like that, but it doesn’t. Just like your colour printer can only print as high quality an image as your provide it, your laser works the same way. Your input has to be as great or greater than your intended output.


Power at 100 is the same for both a basic and a pro GF. Full Power is different between the two units. So if I had said full power, I would also need to say on a Pro so those with basic units would know they may not have the same results at full power.

Yes, I’ve been using 270 lpi when I engrave anodized aluminum with very good results.