Is That Clear???

I’ve done a good bit of experimentation with printing clear bits, both with clear filament (FDM) and resin.

One specific rabbit hole I’ve delved into is using transparent 3D printed parts to enhance light from LEDs. Eventually I’ll add a section dedicated to this topic, but for now here are some examples of things I’ve worked on:

• diffusers to soften the direct output from LEDs
• shaped light pipes to evenly distribute light in a desired area
  • for example, a panel in a stained glass window
• moving light with optical fiber
  • adapters / lenses to efficiently collect LED output and get (most of) it into the fiber
  • mounts / lenses / light pipes on the other end to display the light
  • some clear FDM filaments actually work half-way decently as optical fiber
  • getting seriously into designing custom parts to do this requires wrapping your head around total internal reflection , which is a substantial rabbit hole all by itself
• various combinations of the above to when areas you want to light
  • are smaller than an LED
  • contain in irregular shapes or (multiple light) patterns difficult to cleanly illuminate directly
  • contain many lights on the surface of an object where it’s easier to route optical fiber to each location from a central multi-LED strip or panel than creating a wiring harness for many individual LEDs

In general, printing solid transparent objects can be surprisingly challenging. Just spooling up some clear filament (or even filling your vat with clear resin) probably won’t get you the results you were looking for. You can improve results with a bit of effort, but keep your expectations realistic. Each step closer to “looks like glass” clarity is usually more difficult than the last.

• Nice looking mostly transparent prints with a slightly translucent frosted surface are usually achievable with a bit of effort.
• Truly “crystal clear” prints are quite challenging to produce with consumer grade printers (if not practically impossible, for example, high quality optical components).

General tips

Google is your friend, take some time to search things like 3d printing transparent objects 

• This page is based on observations from my personal experience, YMMV

Not all “transparent” materials (filaments/resins/…) are created equal

• some will make it easier to approach true transparency
• BUT that may mean tradeoffs (strength, heat resistance, …) relevant to your application

FDM

Printing “clean” transparent solid objects using clear filament and FDM printers can take a little extra effort.

The foremost requirement - which most people figure out on there own - is using 0% infill. However, that isn’t always enough.

I find that - especially for thicker sections - “over filling” helps. Otherwise you may get visible patterns in the interior from places where wasn’t quite enough filament to firmly squeeze/adhere into a solid block with uniform density.

While there’s no simple “right” (i.e. just use these exact settings) way to achieve this, there are a few common tips:

• over extrude - push out a little more filament
• run a little hotter (and potentially with less cooling)

It’s best to experiment a bit until you get results you like, as the actual settings that work best will vary based on which printer and filament you’re using and your other slicer settings.

If your slicer supports it, you want to create a dedicated configuration just for printing solid transparent objects with clear filament

• most do - Cura calls them “Materials”, Prusa calls them “Filamaents”, …
• for each specific clear filament product you use
  • obviously clear PLA and clear PETG are different
  • but Prusament PETG cl , i.e. if you use

Relevant settings to adjust / tweak / experiment with:

• In Prusa Slicer,
  • Filament settings
    • “Extrusion Multiplier and Nozzle Temperature in your Filament section
    • Cooling section
• In Cura -Cura has both custom materials and material settings per profile
  • Custom Material settings
    • Default Printing Temperature
    • Fan Speed
    • maybe Retraction Distance (shorter retraction will probably increase exterior issues like stringing, but might reduce gaps in the interior)
  • Material settings (in profile)
    • Printing temperature (may override default from selected “Material”)
    • Flow (and related like Infill Flow, Initial Layer Flow, …)

Note that there may be be other settings that make a difference, and some of these options may be hidden unless you change your configuration detail visibility (switch to “Expert Mode” in Prusa Slicer, “Expert” visibility in Cura, …)

But I recommend starting by increasing your Extrusion Multiplier (Prusa) / Flow rate (Cura) before tweaking temperature or cooling. For some clear filaments (IIRC especially PLA?) this was all I needed to change.