If you are creating the 3d model yourself, here are some guidelines for having the most success, reducing costs of your prints and reducing post processing as much as possible. Depending on your end goal for your design, some of the recommendations below may not be feasible. Feel free to contact us to further discuss any of these items.
While you can print just about anything with 3D printing, there are still challenges to overcome in designing for the technology. Our goal is for our prints to match your design as close as possible and look as clean as possible, but we need your help to accomplish this.
Please note that 3d printing software works in mm. If you are working in any other unit of measure please include this information with your files.
3D printers only print pure geometry, so you need to make sure your model is smooth enough to print well. If you are using a polygon modeler remember to turn off any rendering shaders since they fake smoothness on the screen.
If your model looks chunky on-screen you will need to add more subdivisions which means adding more polygons. How many subdivisions to add is a tough question since the answer depends on multiple factors. A sphere may look a little blocky on screen but maybe it’s only 10 mm in diameter when printed so, at that size, it will probably print just fine. It’s also possible to go to the opposite end of the spectrum and have too many subdivisions. Going crazy with subdividing will bog down your modeling program, the STL export, the mesh repair program, the slicer and maybe even the printer.
A good example of over-subdividing is making small holes on a typical printer. If you add enough subdivisions to make a perfectly smooth hole the printer won’t be able to properly translate so many small moves. It’s better to use a lower edge count which will produce a smoother printed opening.
Subtracting or Intersecting Parts
Booling uses add, subtract and intersect functions to combine geometry in different ways. It’s an important feature for modeling and for 3D printing in particular. You can easily make a model by taking a bunch of primitives and sticking them together and it will look okay and render okay, but probably won’t print well–if at all.
The problem is mashed together parts have hidden geometry that is inside the other parts, but still gets sliced and printed. This can cause problems with the slicing software–making it take longer to finish, or even crash–and the resulting model will often be messed up, have holes or weird geometry problems.
Even if the model slices properly it will take longer to print and use more materials since all that hidden geometry is being printed as well. In the long run it’s far better to suck it up and combine all the parts into one shell using the boole function.
This is kind of an M.C. Escher, impossible geometry problem where more than two faces of an object share the same edge or vertex which is bad and will cause print errors. Or if it prints fine parts of the object may fall off. You may have to rebuild a portion of the object to correct this problem or use mesh repair software.
Supported walls are walls that are connected to other structures or connected on at least two sides. The minimum thickness that your model should have at any one given point is 0.8mm thick for plastic filament printers and 1mm for SLA/DLP resin prints.
Unsupported walls are walls that are connected to the rest of the print on only one side. They should be at least 0.8mm thick for plastic filament printers and 0.5mm for SLA/DLP resin prints.
Embossed & engraved details are features on the model that are raised above or recessed below the model surface. They should be at least 0.6mm wide and 2mm high/deep for plastic filament printers and at least 0.1mm for embossed and 0.4mm for engraved for SLA/DLP resin prints.
The minimum diameter of a hole that can be successfully printed is 2mm for plastic filament and 0.5mm for SLA/DLP Resin printers. Holes any smaller will need cleanup work and possibly need drilled out to proper diameter.
The minimum pin diameter for plastic filament is 3mm and 0.5mm for SLA/DLP printers.
For objects such as pipes with an S curve – printing vertically on its side does not have a high success rate and require a lot of supports that will need cleaning up. We recommend bisecting the part so there is as large of a flat surface as possible to go against the print bed. The two pieces can then be glued together and seams cleaned up.
Connected and Moving Parts
For parts such as print in place hinges or gears, the moving parts should not be closer than 0.3mm for high res prints and 0.5mm for low res prints. Any closer and the parts will probably fuse together and break when forced apart.
Minimum Features such as posts or pints should not be smaller than 2mm for plastic filament and 0.2mm on SLA/DLP to ensure it will not fail to print.
The main thing to consider when designing hinges is how much clearance there is between the two moving pieces. Most people have a decent amount of success with a clearance on all sides of at least 0.3-0.4 mm between pieces, but to be safe we recommend a minimum 0.5mm clearance especially on larger or more complex pieces. Also, make sure the pin area isn’t too long. A good rule to follow in 3D printing is to not have the length equal more than 2x the width, the parts should then be able to withstand lots of usage without breaking.
Supports are needed to hold a part up (we can not print over thin air). Supports are like scaffolding and can leave surface imperfections where they touch. these areas can be cleaned up by sanding or smoothing done by us or by you. We prefer to orient parts so that supports are on the least viewed side of the print or in the case of an enclosure, the inside of the part to reduce the amount of post processing needed.
While it is great to have a print printed in one piece, breaking a print into multiple pieces and assembling after the fact can result in much nicer looking prints.
The maximum angle we can print without requiring supports is 45° in plastic filament. Unfortunately for SLA/DLP printing most gaps and angles require supports.
Horizontal Bridges are the span that can be printed without the need of support. While bridging can be longer under the right conditions, you should keep bridging lengths less than 10mm. One of the shortcomings of resin printers is that they do not handling bridging well.
Specifically for SLA/DLP Resin Prints
For large or hollow SLA/DLP resin prints drainage holes are necessary to prevent uncured resin from being trapped inside the print. These holes can be plugged after the print is dried or hidden in the design. Escape holes should be at the bottom of the print as it is oriented on the printer bed.