The 3D Printing Bible
- 1 What is 3D printing?
- 2 Designing Parts for 3D Printing
- 2.1 The Big 3 No-No's
- 2.2 Things to keep in mind while designing a 3D printed part
- 2.3 Things to consider before emailing us your model
- 2.4 Things to consider while waiting for your print
What is 3D printing?
3D printing is the epitome of rapid prototyping, or quickly creating an object for testing purposes. There are several different types of 3D printing, each one serving its own uses and niche.
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This is the type of printing we do in house. This works by moving a "print head" and "print bed" in 3 dimensions. The "print head" is composed of a heater, temperature probe, and an extruder. The extruder is a metal part that has a small hole at the end of it to let the plastic filament out. The print bed is a flat piece of glass where the plastic is layered on to print the model. In order to print something, the printer will lay out a 2D "layer" of plastic, move either the print head or print bed by some small distance in the Z direction (usually .06-.2mm), and repeat the process until the print is complete. There are some important limitations of FDM printing: Overhangs must be supported from the bottom (This includes holes). They are very slow, taking from 4 hours up to a week to complete a print, depending on size. Finally, they can only print a single color for the entire print. The Ultimaker 3 can print in 2 different colors, but we use the second color for a support material that produces cleaner prints.
Designing Parts for 3D Printing
The Big 3 No-No's
Not every part that you submit to be printed will be accepted. Some models are impossible to print. Some examples of these are provided below, but please keep in mind that this is not an all inclusive list.
The maximum print volume of our printers are 197mm x 215mm x 300mm, or 7.75in x 8.46in x 11.81in. That being said, we will usually reject prints that exceed 4in x 4in x 4in unless you provide a good reason to need a print larger than that. The amount of time it takes to print something increases by the size of the print cubed. The 4in^3 maximum size is to prevent unnecessarily large prints from taking all the available printing slots. We may suggest that you send your part to STS to be printed if it is too large.
In general, small holes that require support (Usually between 2mm-8mm, depending on thickness of hole) must be oriented in the Z axis so that no support material is required. Removing support material from holes that small is extremely difficult to nigh on impossible. If you are planning to have a small screw mounting hole, for example, make sure that it is on the surface with the most surface area. Tiny holes will be accepted or rejected on a case by case basis.
Fully Enclosed Holes
A fully enclosed holes is a hole that is inside of your part, such as making a spherical cutout within a solid cube. It's impossible to remove the support material from these, so we can't print them.
Things to keep in mind while designing a 3D printed part
3D printing is finicky, and often prints fail because of an improperly designed part. Taking the time to make a good, well designed part will result in a better looking and better functioning print.
Keep your prints as flat as possible
The thinner the print, the quicker it can be printed. This also decreases the amount of support material required.
Align as many holes with the surface with the greatest surface area
This means that your holes should be on the bottom surface of your model. Holes generally come out better when they are normal to the Z axis, and putting them on the bottom of your part means that no support material will be required to make the hole.
Minimize the number of hard angles
Fillet as many edges as you can, since models with hard edges (excluding those on the bottom surface, DONT fillet those) tend to have more noise.
Make your walls thin
Unless your part will be bearing a large load, walls should be kept thin (1-2mm), any wider and you start wasting material, and it takes much longer to print your part.
Double check your units!!!
It happens a lot more than you think, please make sure you are sending us a 50mm^3 part instead of a 50in^3 part.
Things to consider before emailing us your model
If you are concerned that your part won't be 3D printable, send us your .SLDPART (SolidWorks files only at this time) and we can try to fix it for you. If it requires a lot of modification, we will not modify your files, and instead give you a list of requirements that need to be met before your model can be printed. This is because we don't know your design intent with the part, and don't want to incorrectly redesign your part. This is also a convenience, please do not abuse it. We reserve the right to refuse to help you if we think you're abusing the privilege.
Things to consider while waiting for your print
Keep in mind that there are other people who need to print things as well. Prints are printed in a first come first serve manner, unless there are extenuating circumstances that require a model to be printed sooner. If your part is time sensitive, ask your TA to send an email to us and we can try to work with you. That being said, sending us a RasPi case 5 hours before demo day starts does not count as "time sensitive". These will be taken on a case by case manner.
Prints usually take between 16 hours to 3 days to complete. Night light cases usually take 4 hours for a well designed box, up to 8 for a poorly designed one. Please add a day or two of prep time for us to slice your model and add it to the queue. In the last few weeks of the course, it may take up to 10 days to get a part printed, because that is usually when the queue is largest. It is highly recommended that you design your models sooner rather than later.
Sometimes the printers break. Sometimes prints fail 95% of the way through their print. Things can come up that can delay when your print is finished. We do our best to keep everything running smoothly, but there are things that are outside of our control. Usually, we will not notify you of any unexpected delay, but we may notify your TA if it is going to seriously impact the timing of your print. Please don't email us asking where your print is. It is either on a flash drive or being printed. No, we can't make it print faster. No, we can't magically un-break the printer without parts. Yes, we wish we could do those things.