What to do, when you want to 3D print something?

The Interaction Lab printer is meant for people to try the 3D printing process themself or if you want to try some materials that other places do not want to do. If you just need to get something 3D printed you can go to the SmartXP or the DesignLab. Before you start to experiment with printing there are some basic things you need to know about the process. Also, make sure you have done the following tutorial Prusa MK3S Academy. You do need to make an account for this to do it but it is free. This tutorial goes through the basic things when using the Prusa i3 MK3s+ printer that is available at the Interaction Lab.

The printer needs to be reserved when you plan to print. Keep in mind you are only allowed to print during office hours (so no overnight print jobs). For longer prints you should go to one of the other labs.

And most important: ask permission if you print something else than basic PLA or PETG with no additives (glitter, glow in the dark, carbon fiber, wood).

Basic overview

The 3D printing process has three major parts;

• Making / downloading the model
• Slicing the model
• Printing the model

Since this is about the print process itself making/downloading the model will be skipped. But there are lots of sites to download models. Just make sure the file is .stl, .obj or .3mf. You can use these file names to search for something in your google query.

Slicing the model

To prepare the model for printing you need a program called a slicer. There are a lot of good free options available but since we use a Prusa printer we recommend using the prusa slicer since it has profiles for most filaments specifically for this printer the Original Prusa i3 MK3S+.

Prusa Slicer

When you open PrusaSlicer for the first time you are welcomed by the configuration wizard. First click the next button, in this overview you see all Prusa printers all boxes can be unchecked except the box under the Original Prusa i3 MK3S & MK3S+ that says 0.4mm nozzle. Since this is the only nozzle that is currently available at the interaction lab for the printer.

Now press next until you are at the Filament Profiles Selection in this overview select the right filament for the printer. If you can not find your brand/vendor in the overview you can use the generic option. But do make sure you select the right type of plastic since this matters a lot. You would probably be using PLA or PETG, with other plastics please inform someone from the interaction lab. Also, ask someone when there are additional materials in the PLA or PETG like for example;

• Fluorescent
• Wood
• Carbonfiber
• Glass
• Glitter

These things can damage the standard nozzle that is on the printer or clog/block it. When all filaments are selected you are going to use you can Press finish.

Preparing the model in the slicer

When you have chosen a model to print you can tell the slicer what kind of parameters you want. The parameters you choose influence print speed, strength, detail, or plastic usage of the print. You always will have to balance these when choosing the parameters. There are some default print settings you can choose these can be found in the top right corner;

Besides print settings you also here chose the filament u want to use, what kind of support you want, and the amount of infill you want.

These are a great place to start if you want to do some basic things. There are some things you can play with without going into much depth found in the print settings tab.

Layer height

When you use the default 0.4 mm nozzle you would probably want the layer height to be 0.2 mm. However you can increase detail by lowering the layer height, I would not recommend going lower than 25% of the nozzle diameter. With the default nozzle, this means 0.1 mm. But doing this increases the print time since it takes more steps for the printer to finish the model. Thus when you want to decrease the print time you can increase the layer height by up to 75% of nozzle diameter. Which is with the default nozzle 0.3 mm

Shell

The shell is the number of layers you have without infill from the contour of the print. These are divided into three categories;

• Top Layers (Layers at the top of the print)
• Perimeters (Layers around the print)
• Bottom Layers (Layers at the bottom of the print)

Playing with these parameters can increase the strength of the print and also increase the print time if you increase these. In most cases, you want to at least have 2 layers in all these categories, and for the bottom maybe even three. Since the first layer after the infill tends to sag in a bit. When you go as low as two or even three you can sometimes see infill on the outside. So to some degree, it has some effect on how nice the print looks.

Infill

Infill is used to reduce print time and plastic use with a print. A higher infill usually means a somewhat higher print strength but most strength comes from the shell. Infill also influences the top layer since more infill means it has to travel less through the air. You probably do not want to go lower than 10% or higher than 60%. Lower means the top layer can sag too much, higher means that the print might even take longer to print. Since infill that dense makes the printer do more acceleration moves compared to when you make it solid. If you need it this high you probably just want to increase the amount of layer the shell has.

Support

Support is exactly what it says it is, support. Because the printer can not print in the air and usually needs something below it. The slicer builds supports under what are called overhangs. A big disadvantage of supports is that they can be hard to remove and usually leave some marks on the print. Especially when there is support in between sections of the print like within a hole.

In Prusa slicer, you can choose areas that never get support or should get support. But if you leave as is the slicer decides where they are needed and usually does that pretty well. You can choose to turn them off, only have them start at the print bed, only where you tell the slicer you want them, or everywhere. This is up to you to decide since it depends per print where you would like to have support.

Speed/accelaration

In general, these settings decide how fast the printer makes moves in certain areas of the print. Higher means lower print time but also lower detail. The same goes with acceleration and the two are highly related to each other. But of you are a beginner best not to play with these since playing with these settings has consequences for loads of other variables and also is highly printer and material dependent.

3D printing

Since Prusa has made a lot of profiles for lots of filament for their printers. Getting the right settings for the chosen filament and 3D printer combinations should not be something to worry about. But here is some basic information about how the print process self works. A quick warning never run gcode from the internet, always make sure u slice .stl, .obj or .3mf files. Prusa does have them if you find it on there print catalogue for there printers. But those only work if you have there printer and there filament. It is better to just slice your own gcode

Basic principles

3D printing is not 3D but more 2.5D since it layers 2D on top of each other. Every layer is done by extruding plastic through the nozzle at a temperature where the plastic used is in its glass transition phase. In this phase, the plastic is solid anymore but also not fluid. This makes it easy the push the filament through the nozzle with the help of the extruder, without having it leaking or burning. Getting this temperature just right is important but is mostly done by Prusa already for most plastics. The printer moves the nozzle over the print bed with the help of two stepper motors. The printer knows how to move due to instructions from the slicer in the form of GCODE. After the layer is done the printer moves the nozzle up by the thickness of the layer it does the same process again. To help cool the plastic and thus have it droop less, the printer uses a fan that blows over the plastic. To make sure the print stays in place the bed is usually heated, this temperature varies per plastic. Sometimes the use of something like a glue stick or hairspray is needed. Sometimes this is needed since otherwise, the print sticks too good. This is the case with PETG for example. If there is not a layer in between the print and the bed it can take chunks of the bed with it. When starting a print make sure to watch it for the first few layers. If these go right the print will probably turn out fine unless the filament spool is close to being empty.

Fillament runout

When you are printing, especially when it is something big there is a chance that the spool of filament will run out. The printer available in the interactionlab does have a filament runout sensor. That means it can detect when there is no meer filament going in the extruder and pauses the print. In that situation, you can follow the screen on the printer that will guide you through removing the little leftover filament and putting the new spool in. This sensor is also triggered when the filament breaks due to some reason. If that is the case, you can remove the little piece in the printer, and put in the filament from the spool again. If it happens very often there is probably something wrong with the spool of filament you use.

Warping

When printing something with a large footprint, there is a chance that the corners start to lift from the bed. When this is the case there are a few factors that can cause this. But it is hard to diagnose which one exactly, these are:

• The distance between nozzle and bed is too large
• The print bed temperature to low or high
• The print bed is filthy/oily
• You need to use hairspray or gluestick

The best place to start is cleaning the bed with some isopropyl alcohol or warm water with some dish soap. When using water and soap please do it in the sink and not on the printer, just remove the sheet of the printer. But best to use the alchohol wipes that should be besides the printer. It is always good to check if the distance between the nozzle and the bed is correct. This is easily done with this guide from Prusa. This is also necessary if you try a new filament or change the side of the print surface. If it still happens it might be the bed temperature but this is harder to get right and mostly requires trying if the suggested temperature by the manufacturer does not work.

Extrusion

Not all filaments keep their original volume when heating and cooling down. This is why every type of filament requires a different type of extrusion multiplier. If you use a preset with the correct filament does should be correct. But it can still be that you have under or over extrusion in your prints. Under extrusion is when there is not enough filament deposited, which will result in gaps in the layers.

If this happens the value of the Extrusion multiplier has to be higher. With over extrusion the get the opposite, the print will get some layers that will stick out. You get some kind of banding in the print, in that case it need to be lower. But you can also calibrate it with the help of this guide from Prusa.

Usefill links

If you still have some issues with your prints you can use google or start with one of these three websites:

• rigid.ink

• simplify 3D

• all3dp

They have the most common issues with 3D printing with pictures of how to recognize them. And have possible suggestions of how to solve them.

If you want to calibrate your fillament you can use this website. Do not change things about the printer unless you have permission. But the parts about filament can be very usefull. Teching Tech calibrition guids