5. 3D Printing

Hero Shot of the Week

DISCLAIMER: This is not my print but happened just yesterday (the day before our global meeting).

Long story short: a med student/intern from our University Medical Department needed to print an educational model for her studies and to explain to patients what they needed to know. (Medical procedures and symptoms).
But her print was so cool that I want to share it here

❗ If you are sensitive for skeleton stuff do not look. ❗

Photo here

Summary

This is what I did this week for 3D Printing. I am already quite familiar with it. Except with resin printing, but there the printer did not want to work.

Work Process

Intro

Henk and Saco did an introduction for 3D Printing.

We first started to look at the guts of the GCode. Lots of coordinates.

I also learned that we can create the code to generate the GCode. But that seems more work than necessary 😅.

It is an old language created for CNC.

A Slow Motion video of a 3D Printer printing.

Different Materials

In our FabLab ULB we mainly use PLA. We use this filament as it one of the safest one for health concerns. It gives off no toxic fumes and has the smallest amount of released particles while printing. It is also biodegradable as it is made by lactic acid. The same stuff as one of the molecules generated in our muscles.

It is also recyclable but we never managed to do it in our Lab. When tried we had variable diameter. And for why we did not try more is because it is not one of our priorities.

A second reason on why we only use PLA is for simplicity for student. They only need to check if they have enough filament and not bother with the type. We have quite a lot of students who only comes because they are required to. So it is easier for everyone to have only one type.

That said we allow printing in PETG (and TPU) for certain occasions and/or researchers, when students are not present. But no other materials (yet).

Material Comparison Tables

From Prusa From Simplify3D

With these tables we can select the filament / material that we need. This selection can be based on the following main properties:

• hardness
• flexibility
• pollution
• water, heat and other resistance
• ...

It also shows what type of printer characteristics you need:

• special nozzle (ex: brass VS steel)
• enclosure
• ...

Pollution

This is an article about the release of particle while printing.

The main takeaway from the article is this graph (Figure 3) :

You can see that PLA is one of the filaments that releases the less amount of UltraFine Particles. While ABS releases 10.000 times more.

(This is one of the reasons we only use PLA in our Lab)

Recycling

An article about recycling.

Here the idea is to create the filament from plants. (This does not mean there is no special chemical reactions). As the plastic is made plant based it means that there should be already some enzymes that can degrade it.

Another article that talks about the decomposition of PLA.

Here the take away is that PLA can quite quickly decompose in nature. As you can see from the picture / graph bellow some type of PLA can decompose in less than a month.

But this also depends on the printed model and its parameters.

Printers

History

The invention of the 3D Printer is quite complicated as it seems multiple people developed the same technology at (more or less) the same time without the knowledge of the other.

RepRap Family Tree

But this guy video presentation debates the first use of a "3D Printer". It is about a special concrete pourer.

Multi head Printers

With multi head we can do lots of interesting / fabulous things.

One of them is printing in multi-material. This allows us to created flexible objects like this bone hand medical example.

This also allows to print the support in a water soluble material.

It is a better option than a single head MMU as the head does not need to purge each time it changes material.

Programs

MeshLab

So there is MeshLab to optimize the Mesh 3D models. As the last update more than a 1 year ago I was curious if it was abandoned. GitHub says no. Last edit was a month ago.

This app should be useful for D&D figurines.

Prusa Slicer

This is the one that I use everyday. I found it quite easy to use and mostly user friendly.

It has a really good documentation / support page. It also has a quite a big community.

It is an open source program.

You can found my FabLab's tutorial here

Super Slicer

A fork of Prusa Slicer.

home page

FabLab Setup

So here I have, in total 16 Prusa MK3S/S+. 15 of them have 0,6mm nozzle and one of them 0,4mm nozzle (in a separate room). All brass nozzle.

So the 0,6mm nozzle printers are for the students to use. We moved to 0,6 for two main reasons.

1. It prints faster as it can deposit bigger layers. We are a uni FabLab for prototyping not for precise work. The 0,4mm nozzle printer is in a separate room and only accessible for the researchers.
2. Second reason (tbh, I cannot quite recall if it was a reason or a consequence) it was to have less clogs. The printers are less often in maintenance because of clogging issues. Most of the time when a printer has an issue (after this change) is because of an overused cable that broke.

I also have 2 Ultimakers that are currently out of use.

And 1 FromLab Form 2 resin printer.

Design rules

Brick Layers

The article shared in the zoom meeting.

I was curious if it was already present in Prusa Slicer, but seems like it is not based in this open issue. But this would definitely improve the strength of the print. And maybe even its watertightness.

BUT

While in the intro Henk showed us this guy GitHub page where he made a post script to implement the brick layer technology to Prusa Slicer.

So it is not officially implemented but has people working on it.

AH

It is a patent issue...

Testing

So the Print model is the following. An all in one file for the different design rules.

I printed this in different ways:

PS: I also did a Z calibration before printing but this was for my job as some of them needed it.

0.4 Nozzle with 0.15 mm layer - PLA

Print Time: 3h30

We can see that the texts and numbers a clear and readable everywhere. It can also be noted that the overhand challenge passes with great success as there are no real spaghetti / dangling parts under the 80 degree angle.

0.6 nozzle with 0.15 mm layer - PLA

Print Time: 2h40

Even with the nozzle change we can still clearly read most of the texts and numbers. For the overhang challenge we can see that from 70° it start to have spaghetti parts.

0.6 nozzle with 0.30 mm layer - PLA

Print Time: 1h30

Larger numbers and texts are staying readable but smaller ones are not. For the overhang challenge we can see that from 60°it start to have spaghetti parts.

0.6 nozzle with 0.40mm layer - PLA

Print Time: 1h10

Large umbers on the overhang challenge, up to 60° are still readable. Texts are not readable anymore. For the overhang challenge we can see that spaghetti start appearing around 50°-55°.

0.6 nozzle with 0.30 mm layer - TPU

Preparing my print be for TPU printing. (That thing is really nasty and does not want to get unstuck)

Result:

Print Time: 4h50

None of the texts or numbers are readable. The surface finish has many holes. For the overhang challenge spaghetti start to appear around 50°. The print is quite flexible.

0.6 nozzle with 0.30 mm layer - PETG

Print Time 1h40

Texts and numbers are hard to read but that is also because of the filament color. For the overhang challenge spaghetti start to appear around 75°.

Overhang Challenge

The overhang challenge is done to see up to what degree we can print without support and with a decent finish.

The following Web Site is to create model to test your printer.

Resin Printer Test

I also wanted to learn how to use the resin printer from the lab associated with the FabLab. Axel explained how to use it.

Unfortunately the printer does not wanted to print saying that the level of resin is insufficient. But in reality the level of the resin was where it was supposed to be... The resin was also expired... By one month...

So no resin printing for me.
(Yet)

Final project

The idea is to print a pin. This could technically also be made with subtractively but for that we would need a 5-axis CNC. Also it would permit (I think) to make the pin AND the electronic holder (that is missing in this print as I am not there yet) at the same time. (Flat surface will be modified to hold electronics)

So I printed my pin to test if it fits in the holes of my mdf plaque. It broke.

I did not think things through when I did the GCode. The layer directions was made so it could brake easily.

Changed the direction and now it works.

But it is a little hard to take it out. I should try with PETG.

To be honest I did not feel any difference. Seems like it is to small to have a different feel.

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Learning Outcome

I already knew how to use a printer and how to maintain a Prusa MK3S.

But I never printed in TPU yet. It seems wrong to put sticky paper on a printing bed.

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Digital Files and Links

• Pin
• Stronger 3D Prints by injecting Filament into the Infill - Video
• 3D Printed Brick Layers For Everyone
  • Sam's work on it

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Assignment Check

• group assignment:
  • test the design rules for your 3D printer(s)
    • Done
• individual assignment:
  • design and 3D print an object (small, few cm3, limited by printer time) that could not be made subtractively
    • Done
  • 3D scan an object (and optionally print it)
    • Done

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