So I played with all kinds of settings in PrusaSlicer. Nothing changed anything.
The only things that did improve the outcome some was:
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Forcing the letters to be printed first: then the letters are smooshed and bleed into the background instead of the other way round, which arguably looks better / more legible. Nothing to write home about though.
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Dropping the first layer’s height to 0.1mm (the other layers are 0.2mm high): that improves the letters a bit.
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Dropping the first layer’s height to 0.05mm: because the first layer is so thin, it becomes kind of translucent and the wider white letter beneath it sort of show through. The net result is that it drops a kind of gaussian blur onto the lettering, which actually improves them - especially at a distance.
Other than that, there’s just nothing for it. And half of the suggestions I got concern other slicers, and I couldn’t find them or equivalents in PrusaSlicer. Oh well…
I guess that’s as good as it’s gonna get.
Make two separate parts in CAD. You can join them as separate shapes in a Parts Workbench compound or using the Mesh Workbench tools. Then upload the meshed file into the slicer. Empirically tune the gaps to suit your printer.
Just be absolutely sure that the two parts do not overlap in some intersection. The slicer will absolutely try to print twice in the same place.
Personally, I like to use manual inserts or layer changes. Print your text separately in one color. Recess the text in negative for a few layers. Then add a print pause where you drop the lettering into the designed voids and continue the print, letting the voids and bridging bond the inserted letters.
I was messing with a similar issue with my laptop GPU cover design from a few weeks ago. I wanted the layers to separate between the patterns and how the slicer was pathing . I did a bunch of tests and still need to print a final version but uploading the first layer as multiple compounded meshes is the solution.
If you design the 0,0 location of the parts so that they import into PS already aligned but as separate meshes, you can also use the elephants foot or other unique settings to manipulate how each section prints.
The letters are separate parts - well, bodies:
Basically I use the same shapestring to cut the letters into the shell and pad each letter as a separate body.
I thought about somehow pushing the lateral walls of the letter recesses in the shell outward to create a gap around the letter bodies, but I haven’t figured out how to do that smartly in FreeCad. I have a feeling I should work on them as meshes, but I’ve never used the mesh workbench. Is this what you’re suggesting?
Of course, I could also import the body in Blender and do that there.
Wow I’ll have to re-read that when I’m fully awake: you totally lost me there 🙂
They do import as separate bodies that are aligned. I did try messing around with settings in individual parts, but it didn’t do anything.
If you go to the Draft Workbench, there is a special Clone tool there and only there. Clones made in Draft can be resized in the data tab. This is super useful for creating offsets.
What I’m talking about with ‘alignment of parts so that they can be imported’ has more to do with complex assemblies. If you transform a Part Design body, and then build your thing in multiple bodies, they will be meshed in the local origin of the body’s 0,0 coordinate plane. I do this kind of thing a lot. I use a Part Design sketches/bodies/parts workflow almost exclusively. I have to be conscientious of building both parts on the same 0,0 origin.
So with inserts like I was mentioning before, think like the Prusa parts prints for the LCD surround on their printers where they are printing the letters in recessed voids.
Second, – a completely different technique. Think about how you can print a part and setup a void and pause in the middle of printing to insert a bearing or nut, then continue the print, thus embedding the object into the print.
Third, let’s combine these two concepts. You print the recessed lettering and a small void behind it, like with the Prusa print plus a void, and then add a pause to the print. Now you take another print that is only the positive lettering and small backing material. You insert this print as you would with a nut or bearing inserted into the paused print and continue the print. You could print the insert at the same time on the same build plate or print it separate in advance. This method also allows you to mix first layer bed textures, filament materials, or even patterns you design into the lettering to be inserted. Like you can print on glass and have gloss smooth lettering inserted into a print on a course bed texture. Or, look up CNC Kitchen’s guide on printing nearly optically clear PETG by fine tuning the settings. Then you can create lettering that can be lit from behind.
If you have trouble with first layer crispness, print the lettering face up and use ironing to get a flatter crisper edge.
Someone else mentioned a 0.2mm nozzle. They are not as slow as one might imagine. If you’ve never tried it, get one. I have a 0.25 and really like it. I use 0.6mm most of the time, but the 0.25mm is not just for cosmetic details. It will really push your understanding of wall thickness and infill strength. With Prusament PC blend, a 0.25mm nozzle is a lot of fun for designing small and putting materials only where they are needed. If you learn to use the Lattice 2 workbench for creating patterns, things get even more fun as you can skip infill all together and start creating more intentional structures in patterns quickly without bogging down FreeCAD. It is fun to transition into design-thinking in terms of single wall shells and connections. That is one step away from an intuitive grasp of flexures and compliant mechanisms. Like my present little Bluetooth enclosure design uses the flex of curved walls and the thickness of material to press a little dome button on the center of a PCB inside. I didn’t make any cutouts or separate parts to actuate. It is just the flex of the design. I spent today getting it ready to print with a 0.25mm nozzle and clear PETG too. Anyways, GL and happy printing.
Yeah I’m aware of the resizable Draft clones. But in my case, it’s not helpful: in the case of the letter R for example, if I shrink it, the outside of the letter creates a gap but the inside of the letter invades the shell’s material. What’s needed here is moving surfaces inward - meaning outward vertical features move inward and inward vertical features move outward (and horizontal surfaces stay put) which is quite different from wholesale resizing.
I thought that’s what you meant. This is WAY too labor-intensive for my purpose: I print those tabs in batches of 256. I can’t imagine printing 256 tiny lettering inserts and manually placing them iin all 256 shells when the print pauses. That’s crazy!
Is this what Prusa does for their parts? They must be using slave labor or something. Then again, at the price their sell their wares, they can take a few minutes to manually insert parts into their prints…
Face up looks very nice, even without ironing. The issue is, the shells have very thin (one line width) walls, and those would need support. That means carefully removing 256 supports for each batch of tabs, trying not to break the walls. Crazy amount of work. Not to mention, the wall’s height needs to be quite precise, and supports usually screws up with vertical dimensions bad, at least for the kind of precision I need here.
The real issue is, this is the company’s printer. It’s used for printing jigs and things. I’m really trying to avoid changing how it’s usually setup because I don’t want my colleagues and I to change the nozzles several times a day. Also, my boss thinks the markings as I print them now are good enough - which is true enough - so I can’t justify the expense of a smaller nozzle.
In short, I try to make the best of what the printer offers without modifying anything significant.
Yeah, then 2 parts and a gap is best. If you are not using Mesh WB, do so and manually mesh stuff. The default export mesh resolution is quite course by comparison.