Our chosen type of 3D printing process is called fused deposition modelling (FDM). With this we can fabricate any 3D geometry. Consequently we produce parts made from strong ABS engineer polymer, making prints are suitable for functional testing amongst many other applications.
Our 3D Printer has a build area of 254 x 254 x 305mm which accommodates most parts, however should yours be larger than this it is best to split the model into sections that can be printed separately then fixed or bonded together afterwards.
Vertical Layer Resolution
- High (0.254mm)
- Low (0.330mm)
Density (Model Interior Fill)
There are 3 different types part density which we can produce your models in: solid, high density and low density. Each type of infill uses a different type of pattern when fabricating the inside of the part to vary the amount of air space within. This allows material to be conserved, weight to be reduced, objects to be printed faster or alternatively solid models can be made to maximise strength. For high and low interior fill is there will be at least 1.5mm of solid material on exterior walls, allowing plenty of scope for post processing without compromising part integrity. We will be advise which processing is best depending on the desired end use of your parts, but generally these guidelines apply:
- For thin walled parts (<3mm), such as injection mould prototypes, solid interior fill is best
- Solid models should be printed in high or low density to save material and reduce print time unless maximum part strength is desired
- Moulds should be printed in solid for most use cases to maximise their strength
CAM 3DP can orient your models in order to optimise a number of elements: general part or specific feature strength, use of support material, build time and aesthetics. In each case we will consult with you to decide which is most important for your given application.
Currently CAM 3DP only removes the support material as a post process.
Try not to make walls thinner than 1mm, although they can be printed, they will be delicate. For smaller parts a wall thickness less than 1mm may be suitable, but for larger parts it is likely to be brittle; any geometry less than 0.2mm will not be printed.
The best way is to refer to your desired vertical layer resolution in order to choose the minimum wall thickness:
- High (0.254mm) - Min wall thickness = 0.5mm
- Medium (0.330mm) - Min wall thickness = 0.65mm
As models are 3D printed in a heated environment, the deposited ABS material cools slowly and therefore warpage is rare. When using extremely thin vertical walls, ribs should be added to lower the risk of this factor occurring. In 99.9% of cases this is something that shouldn't need to be considered.
The minimum suggested text size on the top or bottom faces of the model is 16pt in boldface and on vertical walls the minimum is 10pt boldface.
Built-in threads can be created using FDM, as long as the threads are not too small, ideally when posts or holes are larger than 3mm and the minimum size of the thread is 0.8mm. ACME threads have been found to be most effective for FDM, with rounded roots and crests to avoid stress concentrators. If ACME threads are not used, avoid 90 degree angles on the thread profile. Threads which start further down post will result in the threads starting smoothly (known as a 'dog point' head)
It is more likely using one of these four methods will create a higher quality, stronger and more accurate thread with more ease:
- Drilling and tapping
- Heli-coil insert
- Heat or ultrasonic weld inserts
- Press-fit inserts
This can be done for a number of reasons:
- The 3D model is too large to fit within the 3D printer's build area
- When large amount of support structure is required sectioning can reduce the cost of a component (e.g. Overhangs at the top of a part require support material to be build all the way up, this could be built separately if excessive).
- Fragile features can sectioned in order for them to be built separately in an orientation which maximises it's strength and prevent damage to them during post processing. It can then be bonded to the main model afterwards.
- Demonstration reasons to see within a model
This is not required on FDM parts.
Rounds and fillets are not required for FDM parts, but as is common design practice, they can be used to reduce stress concentrations and improve part strength. Generally fillets radius can be chosen based on the wall thickness being used in your design.
Holes in FDM parts are slightly undersized by 0.2mm at most depending on the size of hole (larger holes tend to be more accurate). When tight tolerances are require holes can be drilled or reamed if requested.
Fully operational assemblies can be 3D printed in one process should the clearances on the X/Y and Z axes be followed. These clearances should be at minimum the same as the vertical layer resolution (0.252mm or 0.33mm) for Z axis and minimum extrusion width recommended by the suggested wall thicknesses (0.5 or 0.65mm) for the X/Y axes.
Columns and Pins
Pins or columns which are smaller than 2mm will be brittle making them likely to fail, but should be judged accordingly based on the desired orientation of the print, vertical layer resolution and length.