3D Printing Guide
General Guidelines
- Your parts need to be strong enough to print. As a general guideline, all parts of your model should be at least 2mm thick
- The material used in rapid prototyping is EXPENSIVE!!! Rapid prototyping is therefore too expensive to use because of laziness. If your component is a simple turned component, for example, then it may be much more cost effective for you to turn it on a lathe.
- By all means, do use rapid prototyping to test ideas, but this is no excuse for not having your idea as complete as possible from an engineering point of view. Remember that it will take you substantially more time to make changes to the prototype afterward than it would have taken you just to incorporate the changes in the CAD files in the first place.
- Try to avoid secondary operations whenever possible. If for example, your component will have a hole in it, then add it to the CAD model so it comes out as part of the prototype. If you have to drill it manually afterward, then you run the risk of it not being exactly where it should be.
- The only exception to this is tapping holes for screws, which should be done as a secondary operation (though a pilot hole should be inserted as part of the CAD model).
- In general, if your part could not be easily plastic injection molded, then it will probably cost a lot to prototype.
The following points about support material apply only to printing in Plastic.
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- If your component has overhanging features, you must remember that the printer cannot print in thin air. It must therefore deposit a 'scaffolding' system made up of support material beneath the overhanging feature so that it has something to print onto when it gets to the feature.
- The support material is then removed after the part is built.
- If there are no other strength or finish specifications, we will generally try to print the part in the orientation that requires the least amount of support material.
- For solid components of large volume, we have the option of printing the part with a 'sparse' interior. This means that, instead of having a solid interior, the component will have a solid shell on the outside filled with 'scaffolding' in the inside.
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Tips and Tricks for Optimizing your Model
- Keep your wall thickness to between 1.5 and 3mm, unless there is a serious reason to go thinner or thicker. This thickness would also be a good representation of the thickness you would be likely to use if you were injection molding the part.
- If your parts are thin they need to be structurally sound. If, for example, on your part you have a long unsupported bit that is only 2mm tick it is more than likely to break when the part is removed from the machine.
- Avoid large solids as they weigh more and therefore will cost you more. They are probably also not easy to injection mold as they would result in 'sink marks' on the outside of your components.
- Parts are weaker in the layered direction. We have the option of building your parts by positioning them either horizontally or vertically. Let us know if you have any specific strength requirements in a particular direction, and we will try to optimize the build for you.
- Fillet the bottom of all screw posts or other thin protrusions to give them strength. This same rule should apply if you were injection molding the parts anyway.
- The models come out with a reasonably good finish, but exhibit something similar to a wood grain due to the layering process. This can easily be sanded down with a bit of wet and dry paper to give a nice, smooth finish
- The models can be painted using standard spray paints, resulting in extremely high quality finishes
Finding out the cost of your components
Please note that we cannot give you a price (not even an approximation) without seeing your file in STL format!
Please E-mail your files to Olaf at olaf.diegel@aut.ac.nz. We will then e-mail you back once we have worked out the exact cost of your parts to confirm that you want to proceed.
File Format
For prototyping, or pricing, your final files must be in STL format. From within your CAD software use the SAVE AS or EXPORT functions to save your model in STL format.
Please see the page in the downloads section on the right if you want more information on preparing STL files.
Please ask your tutor if you have any questions about preparing your model, etc. |