3D- Printed Track Base
At the beginning of the year, my thoughts turned towards making some track for my Broad Gauge (BG) models. I have already built a short section of track using traditional methods but I decided to see if 3D printing could help.
After some experimentation in the early days of the GWR, the design of prototype broad gauge track settled into the form shown below:
Construction of Broad Gauge Track
The longitudinal baulks were about 30 feet (~ 9 m) long and held at the correct separation by transoms placed at around 8 foot (~ 2.4 m) spacing.
For modelling purposes, I created baulks of 120 mm length, with 4 transoms evenly spaced in each section, so that individual pieces can be butted together, while maintaining constant spacing of the transoms. Creating a 3D model in ‘Fusion 360’ was straightforward, by extruding from a plan-drawing to a depth equivalent to the prototypical 7” (~ 18 cm). I added some surface detail to represent the short packing pieces that were placed immediately below the rails themselves.
Once extruded, the 3D model appeared as below:
My 3-D Model of a section of BG Track
Remembering my old ‘Tri-ang’ track, with its grey plastic base representing the ballast, I thought I would see if it would be possible to 3D-print the ballast. It proved to be far from simple but opened up a whole new aspect of printing with 'Fusion 360'!
Creating Surface Texture in ‘Fusion 360’
I soon found that there appears to be no simple way of adding surface texture in ‘Fusion 360’ – it can be added as a visual effect for on-screen display but not in a way that can be 3D-printed. So, I started researching by means of Google, to see if there were any ‘work arounds’.
I found several references to a ‘plug-in’ for 'Fusion 360' called ‘Image2Surface’. This adds a capability for 'Fusion 360' to create a textured surface from a 2D image. Downloading the appropriate software and then getting it to work was not straightforward but, fortunately, I found a 'YouTube' video, which explains the procedures very well – see: https://www.youtube.com/watch?v=ChdJ8nL7qQA
Warning. The next few paragraphs are rather technical and largely an aide memoire for myself. All the information is in the video above.
At first, I had to keep listening to short sections of the video and then trying one step at a time. For reference, I have made the following précis:
The first step is to download a zip-file containing the software Fusion360Image2Surface-master.zip from the Autodesk Knowledge Network. Mine is the Windows 64-bit version but there is a version for Mac as well.
On my Windows machine, the downloaded zip-file has to be extracted into the ‘Fusion 360 Addins’ folder, where the extracted folder must be re-named to ‘Image2Surface’. The Addins folder is typically located at C:\Users\’user name’\App Data\Roaming\Autodesk\Autodesk Fusion 360\API\Addins
Within the running 'Fusion 360' application, open the ‘TOOLS’ menu and then open the ‘Addins’ drop-down box to select ’Image2Surface’. There is a check box to open this addin automatically whenever 'Fusion 360' starts.
Once the addin is running, simply click on its icon and a new window opens in 'Fusion 360'. This allows you to open a standard JPEG image from your computer. There are various adjustments available, to make sure it has an appropriate amount of detail.
- Once the settings have been made, click on ‘Generate Surface’. The next process may take some time, depending on the complexity of your image, but eventually an image will appear on the main 'Fusion 360' screen.
At this point, there are still several steps to be taken before you have a 3D-printable object.
The surface created by the addin has now to be converted into a ‘body’, which involves several stages, as listed below:
Open the ‘SOLID’ menu and then click on the ‘Create Form’ icon in the ‘CREATE’ section.
A new series of icons will appear. Click below the ‘UTILITIES’ icon to open a drop-down menu.
Click on ‘Convert’ in the drop-down menu.
In the box that appears, select ‘Quad Mesh to T-spline’ in the ‘Convert Type’ selection box, then choose the ‘Select’ button and click on your design. Click ‘OK’ to create a new ‘body’.
At this stage, there are various clever-looking options in the drop-down ‘MODIFY’ menu but I haven’t explored any of these yet.
- To complete the conversion, click the ‘FINISH FORM’ button. There may be another long wait, at the end of which you have a new body but it is still only a surface and is not yet printable.
By now, if you still reading, you are probably feeling ready for a stiff drink but hold out just a little longer!
To make a stand-alone solid object from a surface, create a profile plane below the surface object created by the plug in. In my example, the subject is rectangular, so I drew a rectangle on the X-Y plane below my object, as shown in the following illustrated steps:
Stages in creating a 3D model of ballasted BG track in 'Fusion 360'
Once I had a solid ‘body’ in 'Fusion 360', I could add this to my model of Broad Gauge track, shown above. It does indeed look quite like the old Tri-ang track!
Of course, I realise that, in most cases, 3D printing is not a very sensible way to create ballast and traditional methods are more effective and probably easier to create.
Potential Applications for Surface Modelling
I believe that the real significance of having found this method of creating a 3D surface textures in ‘Fusion 360’ is that it opens up all sorts of new possibilities for model-making. Ideas that spring to mind immediately are surface finishes, such as stone or brickwork on buildings – these could easily be derived from photographs of real buildings. A search on the web for ‘greyscale depth map images’ shows plenty of examples, many of which could be applied as architectural features:
Examples of Depth Map Images from Google
Another possibility is to create 3D nameplates. I found that, by starting from a photo of ‘Rob Roy’ (an engine I have previously modelled), I could convert the actual name plate into a 3D printed model, as shown below:
My 3D-printed nameplate on the printer bed.
Unfortunately, the resolution of my basic FDM printer is insufficient to reduce this to 4 mm scale; the example shown is around 7 mm scale and the detail becomes blurred if I make it smaller. Nevertheless, even with a simple printer like mine, station name plates, shop signs, and the like should all be realisable in 4 mm scale.
For fun, and in anticipation of a more cheerful year in 2022 , I copied an image of the frieze high above the entrance to the Paddington Station hotel!
Paddington Hotel Entrance (created from Google Streetview)
There are good detailed illustrations of the frieze on this website: http://www.speel.me.uk/sculptlondon/paddingtonstation.htm , including an engraving of the pediment, designed by John Thomas in 1854. According to the website: “John Thomas, a now little known but extremely good sculptor, shows his skill at composition in this work. There are 10 full sized figures in the pediment, of which two are seated on one side, one on the other, and three large animals, and yet a perfect balance between the two sides is maintained.”
Of course, it was a very ambitious subject to attempt but I simply copied the engraving shown on the above website, increased the contrast a little, and read it into the ‘Image2Surface’ software. Since the original was not a ‘depth map’ image, I could not expect a highly accurate rendering. The depth of the relief depends on the brightness of the image, so some work to bring forward selected parts of the image, by making them lighter, and to recess others, by making them darker, could help to improve the result.
I converted the image into a sold body, using ‘Fusion 360’ exactly as described above. I then transferred the file to my ‘Cura’ slicing software and prepared it for printing. This resulted in a rather large file and, at first, it seemed to give my printer ‘indigestion’, as it didn’t want to start on my first attempt. After a re-set, it started up, although it initially indicated a print time of 15 hours! Fortunately, this proved to be a dramatic over-estimate and the print actually took about 50 minutes, to produce the following result:
My 3-D printed model of the Paddington Station Frieze
It’s not exactly Hi-Fi, partly due to the limitations of the original image, which was not intended for this purpose, but it would make an interesting addition to a model building.
I think there is plenty of food for thought here, to influence my modelling in 2022.