Engraving Roads on Maps

Have been doing the lake maps for a while, just now adding roads. Normal engrave takes forever, so looking for faster way to do it - for those of you having success, is flood fill or offset fill a better way to go? For offset fill, it looks like I need to cut power back to almost minimal? normally engrave at about 200/26 at 400 lpi.

In order to use 400dpi/lpi, you need to be able to make a spot that is 0.0635 or less in diameter to be useful. I assume it 200mm/s@26%…


Most of these do well to run 0.10mm dot size which is 254 dpi/lpi. Just cutting the dpi/lpi to 254 would probably lower the overall speed by almost half… Half as many passes at the same speed, half the time…

The other half of the deal is how fine is the resulting damage to the material… if the damage is 0.5mm you will have to live with nearly 50 dpi/lpi resolution…


This video is great for determining your dpi/lpi for any laser with any material… Highly suggested you watch it and have a clear understanding of how it works…

Good luck

:smile_cat:

But it will probably deliver better-looking results.

The gotcha with Offset Fill is that the laser cannot reach whatever speed you set for that layer, because it must accelerate and decelerate while following the roads. As a result, scorch marks will show up where it runs slowly, unless you can find whatever compromise power limits that work for that map.

Bonus: you’ll also find gaps down the middle of the roads and holes at the intersections:

Similarly, the caveats for Flood Fill are worth noting:

It’s worth trying, but the irregular fill trajectory will probably become noticeable along the length of a road and all its branches.

I don’t have a microscope, and my eyes aren’t the greatest - but I used a magnifying glass and I think I’m closer to 270 or higher? Gonna do a couple more tests. Truthfully 250 looks closer than 260.

Apply it to the left edge of those patterns and you’ll see evidence suggesting you should fill in the Scanning Offset Adjustment table before doing the Happy Dance:

The raggedy edges mean all those dither pattern dots do not line up properly, which means the overall image won’t look quite right.

Measure the scanning offsets over a wide range of scanning speeds, perhaps from 10 mm/s up through 500 mm/s in steps of 100 mm/s, because LightBurn interpolates between the steps.

Remember to divide the measured offset by two when you fill in the table entries!

Small differences like that don’t mean much, because materials (even different lots of the same material) will cause larger variations. I suspect fixing the offsets will change all the results you see.

Conversely, you can use small changes to work around problems. For example, the distinct banding at 240 which isn’t present at either 250 or 260 mm/s. A 4% speed variation doesn’t make much difference to the “exposure”, but it definitely shows a mechanical resonance in your machine.

You’re right - I never looked that close. Trying to fix the offset now, but even a minimal adjustment (.001mm) seems to make it worse.
This is 100-500mm/s


You did turn the adjustment off before starting the tests, right?

If that’s the case and the tests show 100 to 500 mm/s top-to-bottom, then the offset gets linearly larger as the speed increases, which is about what you’d expect.

If the scan interval is 0.5 mm, then the offset looks like:

  • 0.1 mm at 100 mm/s, so that table entry = 0.05 mm
  • 0.6 mm at 500 mm/s → 0.3 mm

Fill in the other etnries from their measurements, turn the adjustment on, and re-run the tests at the same speeds. The sides should line up just about perfectly, but you can fine-tune them as needed.

Dunno where that itsy came from. Remember, these are not free variables: you must measure the actual offsets, divide by two, and fill in the table.

No, I didn’t measure - not sure if I can measure anything that small - I was going to stick in an adjustment and just keep changing it till it dialed in.

I don’t follow what you mean when you say “You did turn the adjustment off before starting the tests, right?” - do you mean you enter the numbers in the table, click OK, then come back to here and turn off “Enable Scanning Offset Adjustment”?

I ran out of time to test, but I will continue working on this to get it right. Do you happen to have a link to a good video explaining the process?

That pretty much guarantees it will make things worse, because you’re trying to guess the coefficients of an interpolation function.

You can use the scan interval and your magnifying lens to get passable measurements by comparing the left-right offset with the up-down line spacing. Set the scan interval as needed; you can have patterns on, say, five layers with the speeds & appropriate scan spacings, so running the test isn’t such a pain.

Better yet, one of these will come in handy:

https://www.amazon.com/Magnifier-Field-Loupe-Interchangeable-Reticle/dp/B00MMYNQ3A/

https://www.amazon.com/Handheld-Magnifier-Optical-Magnifying-Jeweler/dp/B07R8SPF76/

That’s how you start: no adjustment at all.

Run the tests, measure the results, fill in the table, turn the switch on to enable the adjustments, see what it’s like, iterate as needed.

Not being a video kind of guy, I’m a dead loss for that sort of thing.

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