hello looking for help on trying to raster a two tone acrylic, without going to deep nore making dirt marks, i get it just enought, to almost have a clean look but still not coming out clear, as the older laser i once had. im using a rm laser 120w on dell computer, a rudia controler, and my acrylic sheet is 0.069 inch thick black surface and white under. i chaning image to bitmap, and trying to use the dither options just can’t get it good enough also make two path still comes out dirty.. what am i doing wrong. top acrylic in pic is from old machine epilog and the second one is rm laser.
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In LightBurn, open the Preview window and see if stray ‘white dots’ are intentionally being sent to the engraver. Moving from a Vector Image to a Bitmap image may enable unintended adjustments to the Bitmap. You should also be able to see where the intersecting lines under ‘ALARM CODE’ are left unengraved.
Use the sider at the bottom of the Preview window to watch how the job proceeds and zoom in if you suspect the background is showing stray dots.
Stray dots can also come from an image generation or an image conversion step.
Another source for dots is a High Voltage power supply that inadvertently triggers on ‘machine noise’
That’s probably a step in the wrong direction, because bitmap dithering will make a mess of those sharp edges. Use a simple Fill layer with those shapes.
However, the small squares at the intersections of the lines suggest this started as a combination of thin rectangles on a layer set to Fill, where the intersections of the lines produced small unfilled squares:
Go back to that original design and Weld or Boolean Union the rectangles into a single shape to get a uniform grid:
The rough bottom of the large ovals and slightly jagged edges of the letters suggest the Line Interval is somewhat too large:
The spacing between successive scan line should be about the same as the focused spot size of the laser, roughly 0.2 mm for a CO₂ machine, so running an Interval Test around that value will help fine-tune the spacing for that material.
However, getting good-looking results with a glass-tube 120 W laser (assuming that machine) may be difficult, because the tube probably won’t fire reliably below about 15% and may be somewhat erratic slightly above that level. Engraving at the highest possible speed may let you use enough power to stabilize the beam, but expect to do plenty of experimenting to find the right tradeoff among speed / power / interval / material.
thanks for replying. i have try chaning up different ways of lasering the image just by the normal fill option, and i still don’t get a good result, i tryed many samples for adjusting speed and power. again i turn image to bit map and it goes a little better but still not great, im also pulling all my drawing for corel draw and exporting it and then bring into lighburn but i have to tweek all the image again more of a pain for what i need done, i feel that im going backwards then moving forwards. on my old machine using coreldraw acted as one layer weather i over lap line it will laser exacly what u see. on lightburn seem that if i have a over lap line it invert the lasering and not laser that part. like
[Edited to remove all caps / Shouting at top of lungs]
It looks like you are using a stroke width in CorelDraw. That works fine for Epilog, because it will send the stroke width to the Epilog. Lightburn does not work with a stroke width. In CorelDraw terminology, all of Lightburns strokes are “hairlines”. If you want to make your CorelDraw file look the same in Lightburn, you have to select any lines that are not hairline, and “Convert to Curves”. You would then need to Boolean weld the crossing lines. If you want to, upload an SVG from CorelDraw, and I can look at it in CorelDraw. Or, if you want to upload your CDR file, I have CorelDraw 2019. You might have to append .TXT to the end of the CDR file to upload. Or you can send me a PM
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When engraving with the normal fill option…
When you change machines you may not have the ‘Scanning offset adjustment’ calibrated for the new machine.
The symptom for this is the left and right sides look fuzzy or tassled.
Does the not-good result look like the diagram in the link above?
Flood Fill is for large open areas and it would make a spectacular mess of an equipment label.
Are you willing to share the Corel file? You can drag and drop it into a reply here. If it’s private, you can send it to me in a private message. Sometimes exported files have artifacts. LightBurn can faithfully grab most of them, but when it’s sent to a laser it can create unexpected behavior.
I’d like to see the Bitmap too but it’s probably huge. Do you use Dropbox or another file sharing service?
Yes, LightBurn negates the overlapping areas of closed shapes in the same layer. You can use the Weld feature in LightBurn to weld them together or move them to another layer if you want to engrave the overlapping area twice.
You could also send me the bitmap if it’s not huge.. or if you can share it from your side that would be great.
Glad to see you here Ralph! You’re certainly one of the most advanced Corel users around.
As always, greatly appreciated.
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Thanks for the vote of confidence, but I wouldn’t put myself up on a CorelDraw pedestal. I still design everything in CAD 
hi thank for replying, i will send CRD file i don’t weld any lines in my corel as i didn’t need to for the old machine, im looking for a way to. laser out pretty much same way as the Epilog, did for dither image just im not sure where to start, or what to do, i try few different ways and im starting to confuess myself, on what best setting to have my work come out clear without a dirty look to the acrylic Phenolique. im using two tone. thanks where can i send my file this page won’t let me send, i will export it to dxf for here.
TEST HELP.dxf (1.1 MB)
sorry even when i pull dxf in lighburn i have to re touch my circles for some to be double outline. do i need turn them into object from corel first to not have to alter in lighburn after.
I touched up your file. It only took a couple minutes. The circles needed to have an inward offset to appear as an outline. Your grid needed double lines as well in order to have it fill. As single lines, there is no width and they would not work in a fill layer. It took some clean up work because your grid lines were too long in places.
testhelp.lbrn2 (222.3 KB)
hi im still having trouble to find the right setting for power and speed to come out clear on the laser,. clear as in for the white layer to be white its like im not going deep enought or it to deep or not good interval. 
thanks for helping me the imiage is great that u done.
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Can you upload an SVG file from CorelDraw? And, it would be good to see your settings for Lightburn. @thelmuth offset the circles inward in LB, which will get you close, but you are using (it appears) a 1pt stroke width on the grid lines. The easier fix, if you continue to use CorelDraw, would be to convert the grid lines to curves, and then Boolean Weld in CorelDraw. When you then export a SVG for LB to import, things should be in the right places.
What are the words under the green tape?
Another material test, with lower power may help clean up the results.
Compared to your previous laser, how much more power does your new laser have?
Sorry here better pic without tape.
So whwn u say another test with lower power am i going over the Acrylic twice.
On the old machine was 50w mini epilog, my setting was at this pic below. New laser is 120w
This is an interesting challenge. If you were running a 50W tube at 55% power, you’d need to be able to turn down the power of the 120W tube to..
50W * (55/100) /120 = 23%
Your laser seems to be set up to go lower.
I’d recommend another 10 x 10 material test
700-880 mm/s and 10-19% power
The new laser has a different ‘sweet-spot’.
I’m hoping power can be reduced enough to do this nicely.
The good news is you could expect the new laser to cut 3/4" (19 or 20mm) Plywood.
yes on the old machine those were the numbers over time the number been reduce from speed 75% to 35% and power 65 to 80% cuz it wasn’t lasering good anymore.
but i will do another test grid, the do i need to change any number in here when i do test grid.. for material setting / text setting boarder setting.. or leave it what ever number there..
thanks
I just bought a new 60W and could not figure out why my old K40 etched clearer. I found out that if I turned of Air-Asist that I got a cleaner text. I don’t know it it would help your situation.
A similar situation. Two identical devices (THUNDER BOLT, RUIDA), identical software (LightBurn 1.7.08). One prints perfectly, the other has dirt on the engraving. I drew a test strip directly in LightBurn. I have been suffering for a month, I can not find the reason. I changed the equipment from working to non-working, everything except the pipe. Did not help. I think that the pipe is unstable. What do you say? It is impossible to swap the tubes. Stop production.
same boat as you, 
can’t get a clear look too. hopfully someone has answers.
someone says maybe change the lens to a smaller one, could that be possible? maybe the work i need done is to small of detail to use the normal lens size..