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9 Computer Aided Design (CAD) Sketch Tips for 3D Printing

3D printing isn’t just about learning how to use your new fantastic 3D printer! It also comes with learning a valuable skillset: Computer Aided Design (known as CAD). If you want to maximise 3D printing, you will want to make the most of using CAD to develop your own unique, custom designs you can 3D print.

If you have never digitally designed a 3D object before, it may seem daunting to master a whole new digital skill. So, we’ve put together our 9 top Computer Aided Design sketch tips for 3D printing, for beginners.

For those already highly skilled in CAD, we will be sharing our Design for Additive Manufacturing (DfAM) tips in coming blogs throughout 2022.

All of our examples are shown using Autodesk Fusion 360, which is the CAD software of choice for CREAT3D’s own Application Engineers.

Tip 1 – Design around the centre of the canvas

Starting off in the right place will make the whole design process a lot easier! When you begin your first sketches in Fusion 360, try to centre your design around the centre point of the canvas called the origin point. This enables you to use the planes of the origin to add dimensions, additional planes, or to mirror the object from a set datum point.

When sketching, it is useful to use the ‘Look At’ tool to centre your view of the canvas.

Tip 2 – Use sensible measurements

Ideally, compile a list of required measurements before you begin your design in CAD. If you have total design freedom, it will be easier to print from a design that has clear, rounded measurements, e.g. 20mm rather than 19.397mm.

You can specify the measurements of each sketch by typing them in as you create each part of your design.

It is good practice to consider your printer’s nozzle size when designing. For example, if you are printing with a 0.4mm nozzle, make sure that the dimensions of your design are devisable by 0.4. As a result, when 3D printing, each part of your design will have a solid, complete pass of the nozzle, resulting in a better quality 3D print.

Tip 3 – Use construction lines

Construction lines are great tools to assist in making accurate designs. They are often used as references to aid the creation, dimensions and positioning.

Construction lines in Autodesk Fusion 360 are lines that are not a part of the object to be created, but are used to aid the construction of the design.

When creating a construction line, use the ‘Line’ sketch tool and make sure that the ‘Construction’ button is selected.

You can identify a construction line, as it appears as a dashed line on the canvas.

Now that you have your construction line, there is an array of functions you can use it for.

A good example is to mirror a design across the construction line. Simply select the 'Mirror' tool, the object that you want to mirror, and the construction line you would like to mirror it across. This enables you to quickly provide symmetry to your design.

Tip 4 – Try to use as few steps as possible

When working in Autodesk Fusion 360, the steps you take throughout your design process are recorded in a timeline. You can view your timeline in the bottom left hand of the screen.

It is good practice to try and use as few design steps as possible, to keep track of your process. When all of your steps are organised and made with purpose, it is much easier to go back and make any changes or manipulations to your design. You can even drag steps to reposition them in a different order, or use colour codes for components and groups to keep them organised.

Tip 5 – Avoid sharp edges...fillets are your friends!

Designs with very sharp edges can cause an array of small, but frustrating problems when 3D printing. Fillets help combat these issues.

A fillet is a rounding of an edge or corner of an object. The fillet tool is used to round out sharp edges of an object, making the transitions between faces smoother and stronger.

Adding fillets will make your 3D printing process easier, and your prints will have an improved surface quality while mitigating the risks of warping during the printing process. Fillets can also be used to avoid a 3D printed part snapping or being damaged especially where horizontal surface meet vertical ones.

The design below has lots of sharp edges. However, using the fillet tool to round out edges ensures a much better quality of print, without vastly changing the properties of the design.

Image above: Design with sharp edges

Image below: Design modified to include fillets

Tip 6 – Curvatures make structures stronger

Ever wondered why bridges and structures throughout history use curves instead of angles? It’s because curvatures make designs stronger. This same principle applies in design for 3D printing.

The design below, consisting of many right angles, would be prone to snapping under tension when 3D printed. However, adding curves to the vulnerable points of the design provides reinforcement for an overall stronger part.

Tip 7 – Consider clearance gaps

When designing a part for a specific purpose, particularly if it is to connect or interact with another part or object, it is essential to consider clearance gaps.

For example if you wanted a cylinder of 16mm diameter to fit smoothly through the hole in the cube, the hole would need to be slightly bigger than the cylinder.

The diameter of the hole in this example is 16.4mm, but it is worth experimenting to achieve the ideal clearance for your part based on the geometry of the mating faces.

Remember that tolerances will differ depending on the 3D printer and materials that you use, so you may need to experiment a little to get the best clearance measurements.

Tip 8 - Inspect your design measurements before exporting

It is always worth double checking the measurements of your design before exporting to avoid mistakes. This is quick and easy to do, using the ‘Inspect’ tool.

You can measure between two points, and even check angles.

Tip 9 - Export for the best quality STL

You’re almost ready to print! But first, your design needs to be exported to STL format with the correct settings, to ensure that your 3D print is of the best quality possible.

Want to learn more? The Applications Engineering team here CREAT3D have created a handy guide to walk you through the entire export process, to highlight what to do and what to avoid when exporting your CAD design to an STL.

We hope you find our 9 top CAD sketch tips for 3D printing for beginners useful, and can use these to shape your own learning and designs.

If you’re looking for further hints and tips, or want to explore 3D printer options, contact our Additive Manufacturing Experts.


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