I’ve started engraving stamps over the last few days and I’m seeing a strange failure mode. If I engrave with a ramp setting of 0, everything works consistently. When I enable the ramp feature, some designs will have spots where the engraved area is missed. These spots look clean in the preview window. The problem shows up where there are “vertical” lines close together and the laser should be engraving between them. I’ve attached a photo to show the issue (circled in red). The other stamp correctly engraved without the ramp feature.
In this example, the engraved space is a little over 1mm and I was using a ramp setting of 0.5mm. This is not the tightest feature, but again, it seems like the more “vertical” or perpendicular the lines relative to the scanning direction, the more often the issue shows up.
For this particular design, reducing the ramp setting to 0.3 “solved” the problem, and changing it to 1mm still created issues.
I suspect the distance there isn’t what you think.
Sounds like it’s < 1mm & >0.6mm, as the issue disappears when you shorten/steepen the ramp.
I double checked the measurement there in the original artwork and it’s 1.14mm. I’ve also run a smaller designs where sections with 0.5 mm spacing work fine with a 0.5 mm ramp. It mostly works, except for a few spots where it misses.
If the distance was the issue it would seem to occur at the smallest points in the design, and it doesn’t. Even if the ramp distance is larger than the gap, you would expect it to still engrave the area, just at lower power.
These may seem like small distances, but consider that rubber stamps often include small text (think return address stamps). Those will have many points below 1mm spacing, but you still want a ramp to support the thin lines and small details. The software really needs to be able to handle this resolution.
That’s a nice assumption. If it’s ‘ramping’ on both sides it’s twice as wide… It’s also going around the ‘corner’ when it seems to fail.
I’d take that as it doesn’t work. It shouldn’t have ‘misses’.
I don’t know what the software does when something is requested can’t be accomplished 100% because of size constraints. It’s bound to introduce anomalies.
yes it seems small, but I’ve been making stamps for 5 years and believe me I’ve hit the size constraints - 1 mm shouldn’t be an issue.
From my experience, things get iffy below 0.01 inch (0.25 mm) where the laser tends to engrave too much of the material away and you lose design details in the non-engraved area. Lines below that thickness will look thinner than they should, and if you go down to 0.005 in (0.125mm), parts of the line will disappear. The ramp feature helps this dramatically because you don’t touch the edge of the artwork at full power, but I still avoid features below 0.25 mm.
With that in mind, a 1 mm dimension is huge and well within the capability of my laser and the crappy lasercad software that came with it. I would hope that lightburn would be as good or better.
I trust you… When we start I am pretty clueless to your knowledge as you are with mine. So don’t be offended.
I think @LightBurn probably needs to address the actual issue to determine the problem. You seem to have enough experience to question the results.
If possible for you to post, they will probably want to examine the .lbrn2 file.
You can drop it on the reply window or use the 
icon in the tool bar.
no worries - my experience is very niche, and I wouldn’t have a clue about other applications. Thanks for the feedback.
I’m uploading a file with both the stamp shown in the photo and a smaller version where the issue is more pronounced.
ramp__engraving_test.lbrn2 (332.1 KB)
Been wanting to try stamp making, but haven’t gotten around to it. Many other things included.
Thanks for the upload, I’m sure they would like to look at it. If you don’t hear from them in a few days, ship it and a link to your question to support
ok thanks. I recommend the no-odor laser rubber if you want to play. It used to suck, but the quality of the material improved dramatically a few years ago. The standard material stinks for days after you engrave it.
so out of curiosity, I tried doing an image trace to see if engraving it in fill mode works better. Surprisingly it’s much worse. I’m going to stop messing with it at this point until someone can look at it.
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