3D Printing 101 - Slicing a model

https://www.youtube.com/watch?v=H7brUq9DOdY

Slicing is the first step in the 3D printing process. For most FFF 3D printers the slicer is a piece of software running on a computer outside the 3D printer itself. Your computer. In this chapter we'll go through the process of downloading, installing, and using the slicer to make a GCode file that the 3D printer can use to create a 3D print.

Downloading the example model

To make this interesting we're going to use a file that requires some advanced settings to get right. So to start follow this link and download the file that is there:

http://www.thingiverse.com/thing:33344

This is the tornado vase by Alessandro Ranellucci, modified from Martijn Elserman's original design. This model will work with all slicers and will create a vase... with some clever use of advanced settings.

Downloading your slicer

What slicer you'll be using may vary. If your 3D printer's manufacture suggests a slicer or has their own you should probably use that one. If not you've got a choice. The most popular slicers right now are: Cura, Slic3r, and Simplify3D. To complicate matters even more there are 2 versions of Cura commonly used, an older version, and Cura 2.

• Cura - https://ultimaker.com/en/products/cura-software/list (look for 15.04.06, the last version before 2
• Cura 2 - https://ultimaker.com/en/products/cura-software
• Slic3r - http://slic3r.org/
• Simplify3D - https://www.simplify3d.com/

Each slicer has it's strengths, and different people have their preferences, but for this project they all have the settings that will allow the proper slicing of this model. During this chapter we'll assume you're using one of these slicers on a Windows based machine. If that's not the case these instructions can still be used, generally, but you'll have to adjust for your particular circumstances.

Once you've downloaded your choice of slicer, run the installer and load the slicer on your computer.

If during this chapter one of the slicers has a significant difference from the steps listed it'll get it's own section like this one to give separate instructions.

Slic3r Notes

Slic3r does not have an installer. Instead you'll have to choose a folder on your computer and unzip the slic3r-mswin-xXX-X-X-X.zip file there. Your desktop is an okay choice for this, but I prefer to put it in a directory off my C:/ drive and put a shortcut to the slic3r.exe on my desktop.

Setting Up for Your Printer

Slicers are designed to work with many different 3D printers and their various sizes, configurations, and nuances. Because each type of 3D printer is a little different the first thing a slicer has to do is configure itself for your 3D printer. Fortunately, it's easy to do this.

Run your slicer for the first time.

Cura and Cura2 Notes

The first time you run Cura you will be given a wizard with menus to help you set up your printer. Cura comes pre-loaded with profiles for many printers. Simply choose your printer from the list and Cura does the rest. If your printer isn't on the list you can choose "other" and input the configuration manually. Check with your 3D printer's manufacturer to find out the specific setting you'll need to use.

Slic3r Notes

Slic3r does not have pre-configured printers in it already. Instead, you input the individual settings that pertain to your printer. Check with your 3D printer's manufacturer to find out the specific setting you'll need to use.

Simplify3D Notes

The first time Simplify3D starts up you will see the configuration assistant. (You can get to this any time in Simplify3D from the Help menu.) Simplify3D comes pre-loaded with profiles for many printers. Simply choose your printer from the drop-down menu and Simplify 3D does the rest. If your printer isn't on the list you can choose "other" and input the configuration manually. Check with your 3D printer's manufacturer to find out the specific setting you'll need to use.

Getting acquainted with Your Slicer

As mentioned before, each slicer software is slightly different, while they also have things in common. However, since they're all different, here's the breakdown:

Cura Notes

Cura has the following components on it's main screen:

1. Virtual Build Space - This gives you a visual representation of where your 3D models will be positioned in your build space. At the top-left are buttons for loading in STLs and saving GCode. At the top-right is the view options.  At the bottom are tools for manipulating the selected model including rotating, scaling, and mirroring the model. 
1. Right-click and drag, rotates the view
2. Shift+Right-click and drag, pans the view
3. Moving the scroll-wheel zooms the view in and out
2. Settings Tabs - Here are the settings for your printer, organized in tabs. All the settings mentioned in the previous chapter can be found here.
3. Menu Bar - Other options are available in the menus at the top of Cura

Cura2 Notes

Cura 2 has the following components on it's main screen:

1. Virtual Build Space - This gives you a visual representation of where your 3D models will be located and positioned in your build space. On the left are icons for, from top-to-bottom, loading 3D models, manipulating 3D models, and changing the view
1. Right-click and drag rotates the view
2. Shift+Right-click and drag pans the view
3. Moving the scroll-wheel zooms the view in and out
2. Print Settings Tab - These are the settings that can be manipulated to alter the print
3. Printer Tab - If a printer is connected to your computer via USB, this tab will allow you to access it directly
4. Save to File Button - This button saves the GCode output
5. Menu Bar - Other options are available in the menus at the top of Cura2

Slic3r Notes

Slic3r has the following components on it's main screen:

1. Virtual Build Space - This gives you a visual representation of where your 3D models will be located and positioned in your build space.
1. Left-click and drag to rotate the view
2. Right-click and drag to pan the view
3. Moving the scroll-wheel zooms the view in and out
2. Models List - The list of all 3D models loaded and some information about them. Above this list are buttons to manipulate the 3D models including scale, breaking models into their component parts, and splitting big models up for printing
3. Views Tabs - You can switch between the different views of the virtual build space
4. Settings Tabs - You can switch between the view of the plate and the settings of the print, filament, and printer
5. Menu Bar - Other options are available in the menus at the top of Slic3r

Simplify3D Notes

Simplify3D has the following components on it's main screen:

1. Virtual Build Space - This gives you a visual representation of where your 3D models will be located and positioned in your build space.
1. Left-click and drag rotates the view
2. Right-click and drag pans the view
3. Moving the scroll-wheel zooms the view in and out
2. Models List - Here is the list of the 3D models you have loaded into Simplify3D for printing. Below the list are buttons for Importing and Removing objects from the build space, as well as a button to automatically arrange the parts on the print bed so they're not overlapping, called "Center and Arrange".
3. Process List - Simplify3D keeps all the settings you use in a group called a process, and this is Simplify3D's greatest strength. You can have multiple sets of settings applied to different parts and even have settings apply to only certain layers so they can change as the print goes up. For now we'll use only one process.
4. Object and View Manipulation Tools - These tools allow for quick manipulation of the objects on the build plate and adjusting the 3D view of the Virtual Build space. These tools include selecting, moving, scaling, rotating objects, as well as, further down the tool shelf, direct machine control and customizing supports. Hover over an icon to find out what it does.
5. Prepare to Print Button - This is the button you will press when you're ready to turn the 3D models into GCode.
6. Menu Bar - All of Simplify3D functions and many more can also be accessed from the menu bar including some limited mesh manipulation tools.

Loading and Manipulating an STL file

The next step is to give the slicer something to slice. You can either import the STL model file from the load menu or you can find the 3D file in your file system and drag-and-drop it to your slicer window.

Import the golvend_fixed.stl 3D model downloaded before, into your slicer. It should be in your downloads folder.

With the STL loaded in you will see a preview of it in your virtual build space. 

In my case the tornado 3D model was too big for the mini printer that I was using, so some STL manipulation was necessary. Use the object scale tool to scale the tornado model to about 45% of it's original size

Cura Notes

Scale in Cura goes from 0 to 1, so 45% of the original size will be 0.45.

Cura2 Notes

Cura2 will automatically scale models that are too big to fit in your build area, and will tell you that it's done so. You can still click on the model and click the scale icon to type in the scale if you wish to.

Slic3r Notes

While is seems like Slic3r has fewer options for manipulating loaded models, like rotating and moving models on the build plate, the options do exist. For instance, in the Object menu in the top Menu Bar or by right clicking on the model you get options for rotating and flipping the models. And under File->Preferences you can turn off the option to auto center objects on your build plate.

Simplify3D Notes

The scale, rotation, and positioning tools in the side bar in Simplify3D allow for manipulating the model with the mouse. If you prefer exact numeric control you can double-click on the model to pull up the model details and type in location, scale, and rotation information.

Creating the GCode and Previewing the Print

Without changing any of the print settings it's time to make a slice of the mode and preview how it will print. It is always a good idea to carefully look over the preview before sending it to the printer.

Cura Notes

Click on the View Mode button in the upper left hand corner, choose "Layers" and wait for the view to load. Along the right side a slider appears. Scrubbing this slider up and down allows for previewing the print layer-by-layer. Some features, like solid layers and infill, won't be visible until you're looking at the specific layer.

Cura2 Notes

Click on the View Mode button in the lower left hand side, choose "Layers" and wait for the view to load. Along the left side a slider appears. Scrubbing this slider up and down allows for previewing the print layer-by-layer. Some features, like solid layers and infill, won't be visible until you're looking at the specific layer.

Slic3r Notes

Click the Preview tab under the Virtual Build Space to see a preview of your model. Along the right side is a slider. Scrubbing this slider up and down allows for previewing the print layer-by-layer.

Simplify3D Notes

Click on the Prepare to Print button in the lower left hand corner and the model will be sliced. The program will change to the GCode preview. In the mode Simplify3D has a whole host of new information and buttons.

1. 3D GCode preview - Your model appears as it will when it prints, with the layers, shells, and infill that will be a part of the final print.
2. Build Statistics - Information including an estimated time to build the print and how much material will be used.
3. Preview Settings - You can change how the preview is displayed and what information is available in the GCode preview.
4. Printing Buttons - These buttons will allow you to start a print either over USB or saving the GCode to a file that can be transferred to your printer.
5. Layer Scrubbers - These sliders allow a preview of the print mid-process so you can preview that the infill, shells, and everything are just as you want them.

The tool bar on the side and top menu is also present, but only the options related to adjusting the view are active.

Adjusting the Settings

Unfortunately this is not how this model was meant to be. This is meant to be a vase, hollow in the middle with an open top. But it's not meant to be that way by changing the model, but by manipulating the slicer. Change the slicer so it prints this model with:

• Infill = 0%
• Top Layers = 0
• Bottom Layers = 10 or 2mm
• Shells = 4 or 2mm

Cura Notes

1. To the left of the 3D view, click the Basic settings tab
2. Set Shell thickness (mm) to 2
3. Set Bottom/Top Thickness to 2
4. Set Fill Density % to 0
5. Click on the ... button next to the Fill Density % setting
6. In the Expert Config menu that pops up uncheck the Solid Infill Top box

Note that for Cura the Shell Thickness and Bottom/Top thickness is a measurement of millimeters. Cura automatically calculates, based on your nozzle diameter and layer thickness, how many of each of these to add. Also note that the layer view is updated as you work.

Cura2 Notes

1. On the right-hand side under Print Setup click the button that says Custom
2. Expand the Shell accordion menu 
3. Change the Wall Thickness to 2
4. Change the Top/Bottom Thickness to 2
5. Expand the Infill accordion menu
6. Change the Infill Density to 0%

That takes care of most of the settings, but the top of the print is still filled in. Cura hides this setting deeper.

1. Hover over the Shell accordion menu to make the gear icon appear
2. Click the gear icon
3. In the Settings Visibility menu that comes up check the Top Thickness and Bottom Thickness check boxes
4. Click Close
5. Set the Top Thickness setting to 0

One of Cura2's biggest strengths is that while you can control every minutia of the printing process, it hides most of those settings giving first-time users a much more friendly experience, but it doesn't make them hard to find for experienced or growing users who don't mind learning.

Slic3r Notes

1. Click the Print Settings tab
2. Under General change the Layer Height to something between 0.2 and 0.1
3. Change Perimeters to 4
4. Change Solid Layers Top to 0
5. Change Solid Layers Bottom to 10
6. Under Infill change Fill Density to 0
7. Click the Printer tab to go back to Preview mode to verify the changes took place

Slic3r has an expert mode that provides some more settings and lays things out in categories with a sidebar to help you navigate them. For the improved navigation alone many people prefer expert mode. But all the settings this project needs are available in simple mode.

Simplify3D Notes

1. Click the Exit GCode Preview button.
2. Click the Edit Process Settings button.
3. Move the Infill Percentage slider all the way to the left (0%)
4. Click the Show Advanced button.
5. Click the Layer tab.
6. Set the Top Solid Layers to 0
7. Set the Bottom Solid Layers to 6
8. Set the Outline/Perimeter Shells to 4
9. Click Ok

Printing the Vase

Now that the settings are correct, create the GCode and Preview the print, same as in the " section above. Notice now that the model is hollow with an open top, a perfect vase. This model does not require any supports because of clever control of gradual overhangs. If your printer is connected to your computer via USB you can start printing or you can save the GCode file and get that file to your printer, either on an SD card or some other way to start printing.

Cura Notes

The slicing is done on the fly, so all you have to do is click the Save Toolpath in the upper-left of the 3D view to save the GCode file.

Cura2 Notes

The slicing is done on the fly, so all you have to do is click the Save to File button in the lower-right to save the GCode file.

Slic3r Notes

The slicing is done on the fly, so all you have to do is click the Export G-code button above the models list to the right to save the GCode file.

Simplify3D Notes

Click the Begin Printing over USB or Save Toolpaths to Disk button on the GCode preview, depending on how your printer is set up.

Printing over USB vs SD card printing

When it's an option, why choose to print over the USB vs saving the GCode to an external media like an SD card and inserting that card into the printer? Each method has it's advantages, and in the end it usually boils down to a personal preference. Ultimately the choice is yours.

Printing over USB

Printing over USB is great because it means you can start your print at the push of a button. However, it has some disadvantages. Your printer must be located within a USB cable's length of your computer at all time and especially during a print. because you're computer is feeding each instruction to the printer as it needs them, if your computer or the USB connection fails during the print your print will fail.

Printing from an SD card

Printing from an SD card involves the extra step of removing the media from your printer, inserting it into your computer, copying the file, and transporting it back to the printer. Some printers allow you to do this over wifi, which can be preferable, but it's still an extra step. However, it frees your printer from your computer so you can put it and it's noise in any well ventilated area you want. Because your printer isn't waiting to be fed commands from your computer it can sometimes print faster, more reliably, and smoother, especially with older and cheaper 3D printers.

The Final Print

Remember, you've manipulated your settings to make this print happen. You'll have to reset them back if you don't want all future prints to be vase prints.

Cura2 Notes

This is one area where Cura2 really shines. Every setting you changed from the default has a reset icon next to it, so you never have to question what the recommended setting is and it's easy to reset back to base.

Conclusion

Controlling your slicer means controlling your 3D printer. It allows you to tune how long a print will take, control how much material you want to use, and other aspects of your model. Sometimes startling results can be achieved by manipulating the settings, like in the case of vase printing. Also, many slicers have advanced features that make them desirable over other slicers, like Cura's lithophane generation function. Becoming acquainted with those settings will further allow you to become a 3D printing master.