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Creating Content for 3d Printing

Software for designing 3d objects

We are often asked what software we use to create 3d models for printing.  The answer depends on the type of project.   This potted guide explains some of the software we use in the production of our 3d models.

The basic workflow for any 3d printing or CNC project is

  1. create a digital 3d model.
  2. break this down into commands the machine can understand.
  3. send the commands to the machine.   

In this article, we are mainly concerned with the first step, creating the digital 3d model.

The right tool for the job

If the model is driven by dimensions, say it has to have a specific pattern of holes, or a specific size,  we use CAD (Computer Aided Design) software.  

Some projects involve more organic shapes, or a highly detailed surface.  For these, we use mesh modelling tools. 

Repairing issues with mesh files is a specialist job for mesh analysis and repair tools.  

Sometimes, mainly for CNC and laser cutting,  we just need the outline, or a path to follow with an engraving or cutting tool.  For these we need drawing software that can create paths or vectors. 

CAD (Computer Aided Design)

CAD software is all about dimensions.  If you know that something has to be a certain thickness, with specifically sized holes in exact locations, these can be created in CAD software in a matter of seconds.   In CAD software, if the dimensions change later in the design process,  you can quickly find the parameter, and change it.   The software will apply the change and update all the downstream characteristics that depend on that parameter.   So,  if you placed a feature in the center of an object, but later change its width or length,  your feature is still in the center.

This ability to drive the design by defining and updating parameters is known as parametric modelling, and it is very powerful.  Especially when working in an iterative design process where changes are frequent.

CAD Drawing Example

CAD File Formats

CAD software has been widely used for decades.  Over the years, several industry standard file formats have emerged. It is usually straightforward to import and export files between different CAD packages using these formats.  IGES and the newer STEP format are the most common.  These file formats preserve all the dimensional data in the design.  

For 3d printing however,  files need to be exported in a mesh format. The most common format is  STL (Simple Tesselation Language).  The STL format describes the surface shape like a digital lump of clay.  STL files contain no information about units, colour or materials.  While you can still take measurements,  the STL format does not contain any of the parameter information from the CAD version.  Converting to STL format creates a series of triangles for the surface.  A flat plane can be described using a few of these triangles. A sphere may use thousands.  If you zoom in on a curved surface in an STL file, it will be made up of many small flat surfaces.  If the resolution of the surface is not high enough, these will show in your final print.    

While editing CAD designs by updating parameters is fast and easy,  making changes once it has been converted into STL format is difficult and time consuming. 

At Celtic3d, we use Autodesk Fusion 360 for design work on a daily basis, and occasionally SketchUp which is popular among some of our architectural clients.

Mesh Modelling

When working with organic shapes, say a landscape or a figurine,  it is more important to have precise control over the overall shape and form rather than just be driven by dimensions.   More like digital sculpting than engineering design.     It may also be necessary to make changes to an existing STL file where the original CAD version is not available.   In these cases, you need to use software that allows direct editing of the surface mesh.

Mesh software breaks down into two main categories,  analysis and fixing of issues with the mesh, and authoring tools to create your own mesh from scratch.

What's a Mesh?

A mesh comprises of a series of vertices (points in space), connected by edges (connecting two vertices) and faces (enclosed by three or more edges).   While the STL file format works with triangles,  Faces with four edges (quads) are easier to work with when editing.   It is also possible to work with faces with more than four edges (polygons). 

For 3d printing,  the mesh needs to have thickness and volume, fully enclosing a space without any holes.    A mesh that successfully encloses a volume is known as watertight or “manifold” and is essential for 3d printing.  If 3d printing software comes across holes in the mesh, or a face that does not enclose a volume,  it will either fail or have unpredicted results when trying to print.

Default Blender Cube
The default Blender Cube. A mesh comprising 8 vertices, 12 edges and 6 faces.

Fixing Issues

Getting the mesh right is critical to a successful 3d print.  This applies equally to files that have been exported in STL format from CAD software and to files that have been created from scratch in mesh modelling software. It also applies to 3d models that might have come from another source – like a 3d scan.  

Scanning software creates thousands of reference points from an object, known as a point cloud.  Many scanning packages can convert these point clouds into a mesh.  Essentially this involves treating the points as vertices and joining them together with edges and faces.  The resulting mesh often needs clean-up to fix holes in the model where the software found insufficient points to join together.

At Celtic3d we use several industrial strength tools to analyse and fix mesh issues prior to 3d printing. 

MeshLab (http://www.meshlab.net) is available as Open Source under GPL licence and is an invaluable tool to find and fixing issues with your 3d model file.  It has features to automatically find and fill holes as well as fix the most common mesh issues.

Creating Your Own 3d Models

While exporting from CAD, downloading STL files from the web or scanning objects are all viable ways to get your 3d model file.  Often 3d modelling from scratch is the best option.  Our go-to software for creating 3d models from scratch is Blender.   It is not just a great tool for digital sculpting and mesh modelling.  It is also a full-featured 3d authoring environment. Blender covers everything from CGI (Computer Generated Images), animation, video editing, physics simulations, materials, textures and lighting.

It has superb 3d modelling capabilities and has an included 3d printing add-in (enabled via User Preferences) to export files in STL format.  Like any software of this breadth of capability, you will need to invest some time to get to grips with it.  However, the payback is enormous.  Health warning:  if you get the bug, it can take over your life.   But, you will be joining a massive online community of artists who have created a large library of tutorials and resources to get you started. 

Blender is Open Source, available at blender.org and is a free download.  We encourage you to make a contribution if you find it useful.    

Celtic3d is a member of the Blender Professional Network.

Quick Tips

Creating a guide to using Blender for 3d print projects is beyond the scope of this article.  For those of you who have already dipped a toe in the water, some quick tips for using Blender specifically for creating 3d printable models.

  1. Sort out your scale from the outset.  The STL file format does not include any information about units,  however most software assumes 1 unit = 1 mm in the real world.  Blender, by default, uses it’s own unit scale when exporting STL files.  The easiest way to handle this is to adopt a convention where 1 Blender unit = 1 mm.
  2. Pay attention to real-world sizes and thicknesses.  It is easy to get sucked into spending hours on details that turn out to be too small to see in the 3d print.
  3. Use non-destructive modifiers.  A quick way to ensure that all your wall thicknesses are 3d printable is to model using planes and add a “solidify” modifier to make them a defined thickness.    (Remember to “Apply Scale” when modelling and turn on the “Apply Modifiers” option in the 3d Print utility.)

Vector Art

Although strictly not relevant to 3d printing,  we frequently combine 3d printed parts with 2d CNC machined components in the same model.  CNC machines and laser cutters need a defined path to follow.   These paths, or vectors, are created in 2d drawing software.  We use Adobe Illustrator for this purpose,  mainly because we can also then use Illustrator for other graphics work.   

There are Open Source vector drawing tools available but unfortunately their functionality generally lags behind Autodesk’s.

Closing

Preparing and creating files for 3d printing involves a whole toolbox of software.  Fortunately, much of what you need is readily available and often free to download and try.  Choosing the right tool depends on the type of job in-hand.  We have hopefully given you some pointers.   If you found this article useful, please link and share.

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Celtic3d’s support for PrototAU

Hydrogen powered prototype car

Celtic3d Teams up with PrototAU

Celtic3d are delighted to announce that we are supporting The University of Aberdeen’s PrototAU team for their entry to the Shell Eco-marathon 2020 with their prototype hydrogen fuel cell powered car. 

In 2019 PrototAU entered the Shell Eco-marathon as first time participants,  picking up an award as “Most Innovative Hydrogen Newcomer”.  We were please to provide some practical assistance in making their hydrogen fuel cell enclosure.  

PrototAU

PrototAU are a team of business and engineering students from the University of Aberdeen.  They have set themselves the challenge of designing, building and manufacturing an efficient prototype hydrogen fuel cell car.  Remarkably,  the team of students work on the car as extra curricula activity rather than as an integrated part of their course.

The announcement on the PrototAU Facebook page:

Shell Eco-Marathon Europe

The Shell Eco-marathon Europe is an annual competition between over 130 teams from across Europe and Africa.  There are several categories, for example Internal Combustion Engine, Battery Electric and Hydrogen, in which teams compete.   As well as on-track performance in terms of economy, speed and distance,  participants must pass a stringent technical review of their design and build.    

Practical Help

Celtic3d’s CNC capability can cut sheet material while our 3d printing capability and expertise can produce custom parts in a range of materials.  We are really looking forward to working on parts for the 2020 car.  We can’t wait to see what the design team comes up with.

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3d Printed Augmented Reality baseboard

Augmented Reality and 3d printing

We find the interaction between 3d printed models and mixed / augmented reality a fascinating area to explore.  An opportunity came up for us to explore this further when ASCO approached us with an exciting project for the Offshore Europe exhibition in Aberdeen this year.

A quick note on terms.  Virtual Reality (VR) is where you strap a brick to your face that completely obscures the real world.  Augmented Reality (AR) sometimes called Mixed Reality (XR) lets you see the real world while at the same time,  projecting virtual 3d objects into your view.  This can be via a tablet or phone,  or a headset like Microsoft’s HoloLens or Magic Leap

The challenge: to create a 1.2 meter diameter 3d printed and CNC machined baseboard to be used with augmented reality via tablets.  Oh, and the exhibition is in three weeks!

Design

ASCO’s in-house design team came up with a beautiful stylised design.  Their design incorporated the main elements of their supply chain.  On land the design has a pipe-yard,  a supplier’s facility, the main ASCO base with it’s sophisticated logistics systems, an airport and the new ASCO HQ building.  On sea, an offshore installation, wind farm and shipping.

The model needed to be in colour and fit into a transit case for transport and storage.

Design brief from the client's graphics team
The challenge from the design team. 3d print this 1.2 meters across for an exhibition in 3 weeks.

A key difference between modelling for 3d printing and digital only 3d models is that we need to fully resolve all design decisions before we start 3d printing.  There is no undo button once you have committed the 3d print or started to cut material on the CNC machine.

We decided on three sections for the base.  Making the sea removable would avoid having any of the sections joins being visible on the sea surface.  Also, the offshore platform was to be removable to simplify storing the sea surface in the transit case.  Because some of the surface objects like wind turbines and cranes were fragile, we these made removable for their protection.  So that the model could be used to show a range of scenarios, we left some of the containers the vehicles and the ships unfixed 

3d Models

We took the graphics design that ASCO produced and refactored the 3d models to make them physically printable.   

Some models were simplified, but for others we added more detail.  The warehouse buildings were made hollow with door openings rather than with closed doors.  For the offshore installation, we added fine strut work to the simplified model. 

Selective Laser Sintering (SLS) uses layers of powder which is selectively melted by a laser to form the object.  An inherent advantage of SLS is that due to the presence of unmelted powder it does not need additional support during printing.  This makes hollow buildings and intricate strut-work possible.  We used this characteristic to define fine struts for the drill tower and cranes.  These extra details add intricacy to the model without detracting from the client’s design.  Intricate details are what makes people take a step closer  for a better look – exactly what we want for an exhibition stand.

In making the offshore platform more delicate created a new risk.  Having it so close to the edge of the board made it vulnerable to damage.  To mitigate against this, we made the drill tower detachable, fixed in-place with a magnet.  So, if anyone leans against the drill tower, it detaches rather than breaks.

Machining

We chose polyurethane model board for the terrain.    We carved the model board using our CNC machine.   Due to the size of the model (1.2m diameter),  we machined it six sections.  We permanently joined these sections in pairs to create the three sections for the base.   We used a translucent blue Perspex to simulate the sea which we also cut on our CNC machine.   

CNC Machining model board

Test Version

The main deadline for the project was set up day for the exhibition.  However, it was important to test the augmented reality against the model at least a week earlier than this in-case there were adjustments needed to make the AR work properly.  Although the model had not yet been painted in it’s final colours, we took the assembled model to ASCO’s Dyce headquarters for testing.  It was reassuring to find that the AR was working as expected.

Testing the assembled board with the augmented reality software.

Final Assembly

In the final week, the last major task was painting the model and finally, adding the grass.  We were able to accurately match ASCO’s corporate colours on parts of the model and, guided by the Graphics Team, applied a limited pallet to the remainder.  For grass,  we used green flock with a few scale trees from a model maker supplier. We made water-slide decals to add the ASCO logo in a few strategic locations.

AR Baseboard

Conclusions

At the exhibition, the model, combined with Augmented Reality on a tablet proved as successful as we had hoped in attracting and engaging visitors to the stand.   Having a large and intricate model drew people in for a closer look.  From there the AR played it’s part in engaging and telling the stories behind the supply chain.   

In AR the viewer could see floating labels over key aspects of the supply chain.  With a tap they could bring up further detail and animations with several layers of information. 

The overall model could be used with or without the AR display as a prop to explain key aspects of the supply chain and ASCOs services. 

We have since seen some comments that people liked the model but did not realise there was an AR element to it and had moved on before finding out.  A lesson here is to perhaps add a sign or some indication to the model or nearby that there is more information available in AR.

This project successfully combined the advantages of a model in attracting interest to an exhibit with the ability of digital media to convey information. 

Check out Mark Coull’s post on LinkedIn for a look at the AR content and some reactions to it.  

If you would like to explore how a 3d printed model can help you engage your audiences, contact us to start the conversation.

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Making a replica of the Monymusk Reliquary

Monymusk Reliquary

The Arbroath Abbey Pageant Society commissioned Celtic3d and Angus 3D Solutions, to make a replica of the 8th century Monymusk Reliquary from photo reference.    Quite a challenge, but one that pricked our interest. 

The National Museum of Scotland have the original on display and we have been lucky enough to see it 1st hand.  While some of the pieces are missing,  you can still see the incredibly intricate knotwork and engraving.   Although, some of the original engraving very difficult to make out.    

We needed to include all the intricate knotwork in order to create a 3d model that we could 3d print.  We considered how we would achieve a convincing surface finish on the model to represent the guilding, metal parts and engraved panels.   This was a serious test of our 3d modelling and CNC engraving skills.

The real Monymusk Reliquary. Image by Johnbod - Own work, CC BY-SA 3.0, Link

Getting Our Facts Straight

For any project like this, especially when you have limited access to the original, and need to rely on photos, there is a natural tendency to try to fill in the gaps for yourself by making assumptions about parts you can’t see clearly.   Thankfully, when gathering our reference material, we found there have been a number of detailed academic studies of the reliquary.  A particularly useful source is an article from the Glenmorangie Research Project which describes dimensions, what it is made of, some excellent close-up images and also some helpful information regarding the knotwork panels.

For some aspects of the model,  like the latch mechanism and interior detail,  we couldn’t find an authoritative source of how it should look.  So, rather than make it up, we left these areas plain.

Digital modelling

If the model was being created for 3d graphics,  you would use shortcuts, like using an image file to fake the bumps and hollows.  Because the project was going to be 3d printed,  it was important that details, like the knotwork on the jeweled bosses, were modelled in 3d.   

Blender is our software of choice for this sort of modelling.  

Engraved Panels

To represent the two silver engraved panels on the front,  we chose tooling aluminum.  This comes as 0.127mm thick,  considerably thicker than kitchen foil – but a challenge to engrave without cutting through.    

Using a technique learned for making custom printed circuit boards (PCBs),  we mounted the foil onto some flat hardboard, then probed the surface using electrical contacts to build an accurate map of the surface height of the foil.  

CNC machine making probes of the surface
Surface probing to accurately map heights prior to engraving

This allowed us to accurately engrave into the foil to half its depth without cutting through.   The artwork for the engraving was prepped in Adobe Illustrator and exported as vector art, which can be read by the software we use for CNC machining.

3d Printed Parts

With the 3d model, broken down into component parts, we manufactured them in nylon using a selective laser sintering (SLA) technique.  This gives a robust model that can take some handling, and provides a solid base for paint finishes and further work.

Finishing

Many of the main features of the original reliquary were gilded.  So the obvious choice to replicate the finish was to do the same.   We used imitation gold leaf on the bosses and on the decorated parts of the main body.

Applying gold leaf to the boss parts
Gold leaf applied to the main model

For the other panels we used standard paint finishes applied with an airbrush.    Handpainted the red enamel, and created a wood effect in paint for the interior.   

Jewels were simple rhinestones – which we bought quite a lot of so that we could select the few we needed of the right size and colour.

The Completed Replica

We had the pleasure of hand delivering the completed replica in Arbroath.  The story was covered by The Courier.    We believe the long-term plan is for the replica to be on permanent display at the Arbroath Abbey visitor centre.  We will keep you posted

Read more about Celtic3d’s model making capabilities for Engineering or Architectural projects.

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It’s personal

We received a lovely note from a customer, Andy, who bought one of our clan crest digital designs.    Andy was looking for a way to add a personal touch to a gift for a friend celebrating a milestone birthday.    He thought a 3d printed clan crest design would be an ideal way to add personalisation to a decanter filled with his friend’s favourite Islay single malt.      While he had access to a 3d printer, unfortunately,  we did not have the MacGregor crest available in our shop, so Andy got in-touch.   We were more than happy to create a design for a MacGregor clan crest for Andy.  We have since also added it to our portfolio.

Preview on Sketchfab

Buy the 3d model file

Get in touch

We have quite a few Clan Crest designs ready to purchase and download.  If you would like us to model a Clan Crest not yet in our collection, drop us a line.  We would be happy to help. 

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The Big Build Appeal

Architectural Model

The Big Build Appeal

We are delighted to support local charity, Charlie House with a scale model of the specialist children’s care centre they are raising funds to build in Aberdeen.  

Since we first started supporting Charlie House in 2017, plans have evolved and this is our second version of the model.   Our capabilities have evolved too.  For this version, we tried out some of our new labelling kit to add some colour and extra detail to the interiors.  

We had the pleasure of attending the Big Build Launch event at The Marcliffe (14th November 2018) and found ourselves seconded onto team Charlie for the afternoon to explain the model (or rather explain the build, using the model) to the crowds at the launch.   It was very encouraging to see so many people already engaged to make this project a success.

Picture by Abermedia / Michal Wachucik

About Charlie House

Charlie House are raising £8m to build a state-of-the-art support facility for children with complex and life limiting conditions in the North East of Scotland.  It is shocking to think that there are currently no specialist respite facilities within a 100 miles of Aberdeen and families are having to either make long journeys or to struggle through without the help a centre like this can provide.  The new building will provide a place for the children and their families to get some respite care.    

How you can help

The team have already raised an impressive £1m of their £8m target.  To donate, get involved with fundraising or find other ways to support Charlie House, check out their web site at: https://www.charliehouse.org.uk/  

About our models

Scale models are an excellent way to engage with stakeholders.   At events (like the Big Build Appeal launch) a model works really well as a conversation starter to engage with people browsing past.  Models also work well in 1:1 discussions, they focus discussion on the design and a good model will help you draw attention to the key features you want to highlight.  

For the model for Charlie House,  it was very important that they were able to show the layout and function of the rooms within the building.   For this reason, we made sure the roof and first floor could be removed to show the interior.  We also created small labels with text and details taken from the architectural plans to show what each room was for. 

Using the model, you can see how the family rooms are arranged separate but nearby to the medically equipped children’s rooms, how the social spaces are arranged and where the admin and support areas fit in.  

When showing a bed or a desk,  we raised the label up to the correct scale height, which really helped bring the interior to life and helps people relate to the space.  Another important architectural detail we needed to include, was the use of tinted glass to create a warm glow in some of the communal areas.

For more information and example projects check our architecture page.

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