3d printing end to end
Author: Joris Category: User Manual

I get a lot of questions from people on how to go from design to 3D print successfully. In order to help I’ve made a high level guide outlining all of the major steps involved in 3D printing. These suggestions are by no means definitive but I hope that you’ll find some useful information in here for you.

3D modelling & CAD

maya 3d modeling

CAD or 3D modelling packages are used to create files for 3D printing.

Software such as Autodesk’s AutoCAD is complex to use but a very powerful piece of software used by many engineers worldwide.

Solidworks is also a professional piece of engineering software that you can use for 3D printing as well. If you are a mechanical engineer or see yourself getting involved with making things for the long run, I would pick either Solidworks or AutoCAD. If you have interests in animation as well, then Rhino or Blender would make a better choice.  

Blender is an open source 3D modelling application. It is free and has a strong lively community to support it.

Rhino is also a great 3D modelling tool. Grasshopper is a great plug in for it that makes Rhino much more powerful and lets you do parametric design. Designers tend to gravitate towards using Rhino especially because of Grasshopper.

3Dtin is a super simple online tool that anyone can use to make files in minutes. It is limited but the quickest way to get started. TinkerCAD is a similar tool.

Generally these are the packages I would recommend. They are all good and would let you explore many more fields than just 3D printing. With Rhino, Blender, AutoCAD and Solidworks the learning curve will be steep. These are however good professional tools that in many industries are standards. There are alternatives. If you want to at one point work for Boeing for example, I would take up Catia.

These tools will require a lot of time for you, it is estimated that around 2000 hours of practice would be needed to make you an expert user. I would recommend that you download trial versions of each and try to make a box, a car, a puppet and a gear in each. These packages each have a very different user interface and internal logic in how they let you manipulate things. You should find that one will feel more usable for you. Do take the time to explore each package however. 3D modelling and CAD skills are transferable to a certain degree but it’s best to choose wisely initially so that you don’t at one point have to learn a new package. The more time you spend with one packages the faster and better you become with it.

Once you make a 3D model for 3D printing this model will have to be suitable. The mesh will have to be watertight. It can not have any open holes in it and must not have nonmanifold edges or surfaces. Vertices or faces should not be flipped. Surfaces should not self-intersect. These errors can be repaired by Makeprintable automatically.

Design for 3D printing

printed 3d design

There are a number of different 3D printing processes, each has their own limitations and advantages. Each process also has its own design rules and constraints.

  • Generally minimum wall thickness is an important issue to consider. If an SLS (selective laser sintering) machine can only reliably build walls that are 0.4mm in thickness then all of the walls in your 3D model should at least have this thickness.
  • Minimum level of detail is also important. If the printer can not 3D print details that are less than 0.2mm deep then details or features on your model will not show up.
  • You may want to add textures or patterns to your design, this will work differently depending on your software and the file types used.
  • If you are making a wine glass shape and the top of your wine glass weighs a Kilo but the stem is only 1mm in diameter then it will not work. Sounds pretty straightforward but in many designs we still see things that are not self supporting or will collapse under their own weight. Clearances between parts and clearance between models is also important. With some technologies you can make parts that link together (a standard chain) but with others this is not possible.
  • Some processes and designs require support, depending on the technology this should be taken into account during the design phase (SLS not so much, DMLS hell yes).
  • Different materials on the same printer also behave differently and would have different design rules and constraints.
  • Orientation in the 3D printer will also affect output. A standing 10 CM Eiffel tower would have a 1000 layers and print in 5 hours. Meanwhile the same tower laying flat may print in 2 hours and only have 300 layers. It could be that the tower would look much better once it has been printed laying flat. However in order to print it that way support material would have to be built beneath the curves of the tower to support the build. Desktop 3D printers do not currently do this well so standing up will be the only way to go (Next generation machines should make reliable supports).
  • Generally a rule of thumb initially in order to get your feet wet is “design as if clay.” Imagine your object has to be made on a pottery wheel in clay. Could it be done? Then it will probably print. Don’t start with a random object, initially design something super simple and learn to optimize your workflow. Start with a cube, I know boring. But, mistakes are made in workflow and learn to understand and minimize them from the get go.  

STL

STL is the standard file type for the 3D printing industry. STLs describe your object as a series of triangles. Most authoring packages let you export to STL. The most important thing to know is that there is no predefined unit in the STL file type. Depending on your 3D modeling tool the predefined unit of your tool could be mm, inches or CM. If a 3D printer or 3D printing service receives your file and your object measures 10 by 10 by 10 it has no idea how large it is because the unit is not supplied. I’ve seen a bunch of things go wrong, especially with people working collaboratively due to this. Someone will open and save a file in a package in inches then it will be used in another CAD package in cm and when it uploads to a 3D printing service someone will select mm and the thing will be made in the wrong size. Do pay attention to this.  

Mesh repair

viewer

Meshes can be repaired after they have been 3D modelled. One has to check that all the triangles have the correct orientation and no non manifold edges can be found in the object. Holes and intersections will have to be repaired as well. Makeprintable does this automatically for you. Makeprintable and other file repair tools do alter the geometry of your object. Always inspect a file after it has been repaired. If you’re making a character then it should not be a big deal but if you’re doing a hip implant you may want to check if the thing is still the same shape.

Slicing & settings optimization

Next the object will be sliced and the tool paths for the printer will be generated. In a desktop 3D printer the resulting Gcode will tell the machine how to build the object. In a 3D printing service a bunch of objects will be printed together. These objects will have to be nested eg planned in the build of the printer to print in the best orientation for each part with the highest throughput for the service. Slicers will let you orient objects and this orientation has high impact on the resulting object.

There are also a myriad of settings to consider. In a desktop system extruder temperature, bed temperature, speed, infill and fan speed all have a very high impact on the resulting object. Depending on the object and material these could all be different. Spend a lot of time dialing in a material initially by printing test pieces, then once you’ve mastered the material print with it. A lot of people are taking the random walk approach to 3D printing and this results in failed prints. There are forums and information available on the best profile settings for printers and materials. Please take into account that ambient temperature, humidity, material storage and airflow in the room have huge effects on 3D prints. Its best to print under a fume hood to control for these things. And if you hear from a person in Indonesia that the best settings for white PLA are 203 degrees then this will be very different for you if you are in Norway. For desktop 3D printers one can use Cura or Slic3r to slice. I would recommend both. Just try them out and see which one works better for you. Don’t get Simplify3d, Simplify3d is for noobs. Both Cura and Slic3r are better and also free and open source.

Support generation

Depending on the process different support structures may have to be generated. If you’re new to 3D printing, first make things without supports. Learn to design so that objects require no or very little support when printing. This means that there is less manual labor and post processing in the parts. This will make your parts easier to make and cheaper. This dramatically improves the awesomeness of the 3D printing hobby or the cost of your commercial part.

Dialing in a material

3d printing filaments

Each new material will have to be dialed in. For desktop users materials come with very broad ranges of temperatures. Print a series of test objects systematically at different temperatures. Time spent doing this will lead to many better 3D prints later on. Different colors of material also print at different temperatures. 203-210 is a good starting range for many PLA’s, 208 is my magic number but yours will be different. Reduce the impact ambient airflow, temperature and humidity have on your part by using a fume hood. PLA will degrade if stored out in the open so always keep it in a closed water tight container together with desiccant.

TLC for your printer

Bed leveling is very important in a desktop system. Initially do this before each print you’ll learn to eyeball it and do it quickly, this will reduce failed prints. Bed adhesion is a huge problem for desktop systems. Would not recommend using hairspray since this can gunk up your printer. Clean or dirty bed is usually best. So either a bed cleaned with a high alcohol content detergent or a bed with tonnes of gunky glue remains on it built up over time. PEI sheets are also awesome. Check your end stops and belts often initially so it becomes a quick habit. For best results the printer should be accessible from both front and rear without turning it. It should also be absolutely level and stable. Wait ten minutes after the print to remove your print.

Post processing

3d printing post processing

Depending on your requirements a print can be post processed to achieve a better look or functionality. The most common post processing process is tumbling. This helps smooth out the print and makes layers less visible. Many 3D prints can also be coated or painted for better results. DLP and SLA prints will have to have their supports manually removed and often are sanded. These resin prints also will need to cure in the sun or be cured by a UV flash device.

Happy 3D printing!

The above suggestions are by no means exhaustive but I hope they could be of some help. What are your 3D printing top tips? What suggestions and ideas do you have for those new to 3D printing?

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