Updated: Jul 14, 2021
If you know what you're doing, here is the Fusion 360 file. Have fun.
If you'd like some guidance (highly recommended), read below.
If you're looking to be more efficient in 3D printing the 3DVerkstan face shield then you'll want to stack them. However, there are a few important principles to understand before you can successfully stack 3D prints. I wish it was as simple as giving you the stl file, but doing that will just lead to more wasted time and frustration.
I've already done that for you. I spent two weeks dialing in the settings which included two weeks of failed prints. And because we're talking about stacks, we're talking about waiting 10 hours to find your your print didn't work.
Ok here's what you need to know.
1) You accomplish 3D printing a stack by leaving a gap in between your models as you layer them. The gap distance needs to be small enough to prevent stringing and layer separation but not too small where you have to destroy the two parts in order to detach them.
The goal is to be able to easily detach the layers while maintaining a smooth surface finish on both parts.
So the first thing you need to do is figure out the perfect gap distance for your setup. And by setup, I mean the type of printer you're using, the size of nozzle you have, and the type of filament you're printing with. I found that even different brands of PLA will get you different results.
You'll want to test by first printing a two stack model. I found my range to be between 0.30mm and 0.35mm. So start somewhere in that range.
But before you rush to testing, there are a few more things we need to cover.
2) Your gap distance needs to be equal to your layer height or be an exact multiple of it. If you're printing at 0.2mm layer height, then your gap spacing needs to be 0.2mm or 0.4mm. In my case, my gap spacing was 0.32mm so I set my layer height to 0.32mm.
The reason for this has to do with how your slicer handles, well, slicing. If you tell your slicer that you are slicing with a 0.2mm layer height, the slicer will slice each layer into a 0.2mm section. When it finds a 0.3mm gap, it will either round up to 0.4mm or round down to 0.2mm. And this is where things go wrong.
3) Set your first layer to be the same height as all layers. Some slicers will allow you to change the height of your first layer in order to get better adhesion. You'll want to set this to 100% or manually enter what your layer height is.
Once you have these three things down, you can go ahead and experiment with the gap distance on a stack of two. Tweak the number up or down by 0.02mm increments until you're getting a smooth finish on your top and bottom layer. When successful with a two stack, then try a 5 stack.
I go through all this in the video below.
FYI - in the Fusion 360 file, I made each model 5.12mm high because 5.12 is divisible by 0.32. This gives you exactly 16 layers. When you go to amend the rectangular pattern, you'll see that the spacing is set to 5.44. That is because 5.12 + 0.32 = 5.44.
My big aha! moment with Fusion 360 happened when I finally understood how to use Constraints. Get my free Fusion 360 Constraint Cheat Sheet and see what I mean.