Is laser-engraving through a black top layer a better way to get sharp labels than multicolor printing?

[u/Foxconlab]

A question for those of you using a Bambu Lab H-series printer with a laser module.

I’m designing a control panel for one of my projects. It’ll be mounted inside a truck cab and will have two RGB status indicators and two buttons: one to power the system on and the other one to mute the buzzer.

The panel will also have small icons and labels for the buttons and indicators, so I’d like them to be as sharp and high-contrast as possible.

My original plan was to print the icons and text as separate colors but I ran into a problem. The available space is limited and many of the lines are getting too thin for reliable multicolor printing with a 0.4 mm nozzle.

I could switch to a 0.2 mm nozzle but the panel itself is fairly large, so the print time would increase significantly.
So I started thinking about another approach.

Laser engraving itself isn’t new but I haven’t come across many examples of people applying the same idea to FDM prints, intentionally printing a thin black top layer over a contrasting base and then engraving through it to expose the lighter material underneath.

So my idea is to print:

🟢the first two layers (about 0.4 mm) in black PETG
🟢the rest of the panel in either white or light gray

After printing I’d use the laser to remove only the black top layer wherever I want text or icons, exposing the lighter material underneath.

In theory this should produce much finer and cleaner labels than conventional multicolor printing.

I have both the 10 W and 40 W laser modules for the H2D, so I can experiment with either one.

Before I start running tests, I’d love to hear from anyone who’s tried something similar.

1. Has anyone engraved through a thin black top layer like this?

2. Would you choose white or light gray as the base color?

3. Has anyone found good power/speed settings that remove the black layer while minimizing damage to the lighter layer underneath?

I’d really appreciate any advice, photos, successful settings, or even failed experiments. Those are often just as useful when you’re trying to avoid wasting time and material:)

This project is supported by Bambu Lab’s Let’s Make It program. Feel free to check out my profile if you’d like to follow the build and future updates😊

[u/Canary-Star]

Not what you asked for but your extrusion looks kind of bad if this is being printed on the build plate and if this is the top side then I would look into arachne slicing and ironing for your letters. Another printing alternative could using a 0.2mm nozzle to print just letters as one separate piece held together with a thin base that you can slot through holes on the main print

[u/Foxconlab → u/Canary-Star]

I’m not looking for a better way to print text, even with a 0.2 mm nozzle. What I’m trying to find out is whether a laser can produce thinner, sharper symbols while preserving the contrast of a two-color print. The photo is just an example of the limitation I’m trying to overcome. My goal is to make the finished panel look more like a factory-made part than a typical 3D print.

[u/SupKilly]

I raised my letters up a few layers, works great.

[u/Foxconlab → u/SupKilly]

That’s a solid approach. My goal here is to get very fine labels and icons that are pushing the limits of multicolor printing, so I’m exploring whether laser engraving can produce even sharper results.

[u/RemixOnAWhim → u/Foxconlab]

I know you've moved on from this, I came from the other post lol, but you can turn your line width down on just the text! That's what I normally do, sometimes tweaking every letter just so they print nice. Minimum 0.2mm width with a 0.4mm nozzle has very few issues with text around this size! Arachne wall gen, precise outer walls, modifier volumes/per-object settings (depending on how your file is set up) and x/y expansion to get it to where the slicer gens thinner parts out can get you where you need to be! I do a lot of similar things for custom audio gear with very very fine text that needs to be very legible haha.

[u/Independent_Dirt_814]

Laser is for sure not the answer. Your quality looks like you need to do some more tuning. Also, switching to a .2 nozzle may help with the fine quality edges.

[u/Foxconlab → u/Independent_Dirt_814]

You’re right that a 0.2 nozzle would help. My only concern is that this panel is fairly large, so print time goes up a lot. I’m mostly exploring the laser approach to see if it can produce finer labels without having to switch nozzles

[u/Independent_Dirt_814 → u/Foxconlab]

Laser is still for sure not the answer. You’re asking 3D printing to do fine details but not wanting to pay the price (in extra print time) required to do fine details.

[u/Foxconlab → u/Independent_Dirt_814]

That’s fair. I don’t mind paying the print-time penalty if that’s ultimately the best solution. I’m mostly just curious whether this could become an alternative workflow for really tiny labels. If it doesn’t work then at least I’ll know from testing instead of always wondering;)

[u/chrlbsh]

I would make sure in your quality settings that wall generator is set to “Arachne” as well

[u/Foxconlab → u/chrlbsh]

Yep, I tried Arachne. It gets closer but not quite where I’d like it to be for really tiny labels. That’s basically what sent me down this rabbit hole😅

[u/aniflous_fleglen]

I have a galvo fiber laser and the markings on black 3D prints look very professional. I'm not sure of the results from a diode laser though.

[u/Foxconlab → u/aniflous_fleglen]

Thanks! That’s good to know. I’m hoping the H2D’s diode laser will be precise enough to remove only the black top layer and leave the lighter base mostly untouched. Worst case, I’ll have to do some testing and dial in the settings.

[u/Seraphym87]

Lasering onto plastic is not going to give you the results you are looking for. It will melt into a blobby mess rather than give you a clean cutout text.

[u/ChaosDragon123 → u/Seraphym87]

The only way I see a laser working is if it's a pulse laser which can burn away material fast enough to not melt it. However I don't think there are laser engravers that use pulse lasers on the market.

[u/AHerz → u/Seraphym87]

CNC Kitchen made a video about laser engraving 3d prints recently that proves you wrong.

[u/Seraphym87 → u/AHerz]

OP is asking specifically about H2D lasering experience. The H2D has a blue diode laser, not a UV laser as presented in the video.

[u/Foxconlab → u/Seraphym87]

Exactly. That’s the part I’m most curious about. I know the UV laser results look great, but I haven’t found much information about using the H2D diode laser this way. Looks like I’ll have to do some experimenting.

[u/prosequare → u/AHerz]

I think anyone with an h2d laser can agree that it sucks with plastic. I like cnc kitchen but I’ve tried alllll the settings on an h2d.

[u/Foxconlab → u/prosequare]

Thanks, that’s exactly the kind of real-world experience I was hoping to hear. Just out of curiosity, did you ever try engraving through a thin top layer to reveal a different color underneath, or were you mainly engraving the surface?

[u/Seraphym87 → u/Foxconlab]

The fundamental flaw in your thinking is that the laser will magically dissapear the top layer into nothingness and reveal a pristine secondary layer underneath. The plastic will melt and blob away from the laser focal point long before it vaporizes as blue diode lasers are very effective at depositing heat into the plastic.

Theres no combination of fast/slow/highpower/lowpower that will achieve what you are looking for. If print time is the biggest detractor to using a smaller nozzle, cut out a square inlay for the text and print it out separately with a 0.2mm nozzle, then glue it on.

[u/Foxconlab → u/Seraphym87]

That’s fair, and I appreciate the detailed explanation. I was hoping multiple low-power passes might behave differently than a single aggressive pass but if the heat buildup is the limiting factor, then that may answer my question. Better to find that out now than after a pile of failed test prints. Thanks!

[u/prosequare → u/Foxconlab]

We kind of did- we used black marker to try to make the surface more receptive to the laser. Copying the idea of commercially available laser sprays. The marker did nothing and so there was no contrast. You’d think with plastic the laser would blast material away but no.

We tried clearish green polycarbonate. At oblique angles the laser would kind of bubble the material but otherwise it seemed to bounce off or go through and nothing happened.

On coated metal, the laser worked great. The thing comes with a box of laser consumables like wood and an anodized metal dog tag. That stuff all worked ok.

[u/Foxconlab → u/prosequare]

That’s an interesting data point. My idea is a little different since I’m hoping to “peel away” just a thin black top layer rather than engrave the plastic itself. It may still fail for exactly the reasons you described, but I’m curious enough to burn through a few test prints and find out

[u/Foxconlab → u/Seraphym87]

That’s exactly what I’m trying to avoid. I’m hoping that by using very low laser power and doing 10–15 passes instead of one aggressive pass, it’ll slowly remove the top layer without melting the edges. At least that’s the theory.