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3D Printing at the Milwaukee Makerspace

So you want to learn about 3D printing? We have quite a few printers at MMS in many stages of repair. A list of many of them can be found on the Equipment page. There are usually a few that are able to print attractive plastic objects at any given moment.

Process Overview

3D printer's use G-code, a sort of standardized language for CNC machines of all sorts. You start with a CAD design, export a mesh (aka an STL file), and run it through a program called a slicer. The slicer needs to know about the design, the printer, and the filament you're going to use in order to do its job. The slicer cuts the mesh into thin slices called layers, and figures out how to coordinate all the moving parts of the printer to produce the object you desire, and stores the printer instructions in a gcode file. Getting best results from a 3D printer depends on knowing about the process in general, the specific printer you're going to use, and how to apply different slicer options to the design you're going to print. Expect to have some failures along the way- it takes some experience to get good at it, but you'll figure it all out with a little practice, and there are experts at the Makerspace who can help you.

Before Training

Before you are trained on a printer, you should learn a little about 3D printers, a little about materials, a little about CAD, and a little about creating sliced models.

A Little about 3D Printers

There are many different kinds of 3D printers. Most of the printers at MMS use a method of additive manufacturing called Fused Filament Fabrication (FFF). FFF printers operate like hot glue guns that apply one layer of plastic at a time from the bottom of an object to the top. Most 3D printers have quirks and are nothing like a traditional 2D printer where you press “Print” and your finished product appears in seconds. A small print might take an hour and a larger one could take days of continuous printing. Bugs in the printer, filament, Slicer, model, or preparation can cause a print to fail. Failed prints are nothing to worry about. Give yourself plenty of time and be willing to do a lot of experimentation to get the best results. Here are some common problems encountered when printing. Because of the way that FFF printers create models, overhangs are best avoided during the design phase so that your model can be printed without additional support material. More on that later.

A Little about Materials

Most of the MMS printers use spools of 1.75mm diameter plastic. One spool can print hundreds of small parts. The two main plastics used in FFF printers are ABS and PLA. PLA melts at a lower temperature, degrades in sunlight, is less prone to detach from the base plate while printing, and is stiffer than ABS. ABS snaps less easily, resists changes in temperature better, and smells less friendly than PLA. MMS has spools of PLA and ABS that members can use for small prints or for learning. Keep in mind that PLA and ABS absorb water from the air. That is fine after you print your object, but water makes PLA brittle enough to snap with a slight bend and causes steam bubbles during ABS printing. The best way to keep filament dry is to store it in an air-tight box with Calcium Chloride (DampRid) from the dollar store. Replace it every few months or when it becomes a solid mass. There are many other materials available to print with including Polycarbonate (impact resistant), HIPS (great support material for ABS – dissolves in D-Limonene), PVA (good support material for PLA – dissolves in water), Nylon (very strong), TPEs like TPU (flexible/rubbery), PET (optically clear) and PETG (slightly flexible).

A Little about CAD

CAD stands for Computer Aided Design. It's a way to tell a computer about a 3D object so you can display and manipulate it in 3D.

There are many different CAD packages available. Video tutorials are a great way to see how they are used. Some CAD packages are easier to use than others. You'll see a lot of on-line posts about SketchUp being one of the easy ones to learn. While it is true that it's easy, for a bunch of technical reasons, SketchUp isn't good for designing parts for 3D printing. If you want easy, try DesignSpark Mechanical. OTOH, if you really want to dive in and learn a fully-featured professional package -there are well-paid jobs for people who can use professional CAD- plan on devoting 200-500 hours to become proficient at creating models.

Name Cost Docs Notes
Fusion 360 Free for Makers (for now) Web Help See web site for details
FreeCAD Free, Open Source Web Help Great for Linux users
OnShape Sorta-Free, Closed Source Web Help Professional, Cloud-based, any OS
DesignSpark Mechanical Free, Closed Source Web Help Limited capabilities, but easy to learn - Windows Only
Blender Free, Open Source Web Help Steep learning curve, mostly used for CG art
RhinoCAD About $1000 Web Help Free Trial
OpenSCAD Free, Open SourceWeb Help More like programming than most CAD
SketchUp Make Free-ish Web Help Less than optimal for 3D printing - best avoided

For those who are CAD-adverse, you can download pre-made models from web sites like https://www.thingiverse.com/ and https://www.youmagine.com/ Be forewarned that some of the models at those sites are unprintable on FFM printers like those at the Makerspace. When a model is printable, its author usually posts a photo of the printed object. If you don't see a photo, it may require adjustments to make the object printable. Unprintable models can often serve as inspiration for you to design a better, printable version of the object. Ultimaker has a nice list of model sources here https://ultimaker.com/en/resources/21990-where-to-find-models

Once you have a model, you need to create a mesh file (usually either an STL file or an AMF file). Shapeways has a good list of options for creating them if you are having trouble: https://www.shapeways.com/tutorials/3d-software If someone else created your mesh file and it's broken, you can use tools like MeshLab to repair them.

A Little about Slicing

Slicing software cuts your 3D object into layers that can be stacked to create your object. They can convert solid areas into 3D grids and create extra material to support upper layers with nothing underneath them (like an outstretched arm in a model.) The Slicer outputs a file unique to the 3D printer that you will use. It controls the 3D printer's movement and the speed that it squirts out plastic. Tuning a slicer for a specific printer can take many hours and failed prints. The printers at MMS have pre-made configuration files for Slic3r that work well for most models. Many printers use the G-Code language. You can use a tool like http://gcode.ws to visualize the g-code that a Slicer creates. Here is a reference for writing/debugging G-Code.

Here are a few Slicer packages:

Name Cost Docs Notes
Slic3r Free, Open Source Web Help Widely used, get the latest version
Cura Free, Open Source Web Help Great for Ultimaker printers
KiSSlicer Free, Closed Forum Haven't tried it
Simplify3D About $150 Web Help Haven't tried it

Ready for Training

Before you are trained, you should be at least vaguely familiar with creating a 3D model, turning the model into a mesh, and slicing the mesh. Like all of the plug-in tools at MMS, you have to be trained on each model of 3D printer you would like to use. Training usually takes about an hour per printer and is preferably done in small groups. You will learn some of the quirks of the specific printer and get to know the guidelines for using that printer. To get trained, post to the Members Only Mailing List and offer a few dates and times that are convenient for you in the next week or two. Don't expect to be trained in less than a few days or to meet your deadline. All the trainers are volunteers and they have no obligation to train anyone. They train because they love to teach curious people new things. Tell them about a project you have in mind. Encourage others to be trained with you to minimize the number of training sessions required for each printer. Show up to Tuesday meetings and hang out in the 3D printer lab to learn from other members.

After Training

Review your notes of the training and try a print on your own. If you aren't familiar with something or forgot how to do something, find someone to ask. Many members have used the printers or know someone who knows. If you can't find someone within arms reach, post to the mailing list. Experiment with different temperatures, materials, shapes, etc. Most importantly, have fun, learn, and share your findings with others.

3D Printers at the Makerspace

spacedocumentation/3d_printing.txt · Last modified: 2017/05/14 13:46 by the_digital_dentist