I am grateful for the patience shown by my followers, while I have been wrestling to make progress on 3D modelling, against a background of many distractions!
In my previous post on this subject, I described my progress in understanding how ‘slicer’ software turns a 3D computer model into a file suitable for 3D printing. This enabled me to make a few test prints by downloading 3D models from the web.
3D printed carriage from file on web
The experience has left me with some reservations concerning the 'Geeetech E180' printer that I bought. It is a very neatly-designed machine, which fits well into the domestic environment, but the best results I have managed to obtain, so far, appear to lag behind some other low-priced printers. More importantly, technical support is poor and I suffered a print-head failure after a very short period of use. The print heads are a clever modular design that can easily be unclipped and replaced.
Geeetech E180 print head assembly
Unfortunately, spares seem to be unobtainable in UK and I had to place an order for a couple of print heads, directly from China. These took about a month to arrive, which somewhat dampened my enthusiasm for exploring printing possibilities much further at that time.
My original idea was to look into making components, which lay outside the capabilities of my 2D Silhouette cutter, for some of my loco and carriage designs. This initial plan was side-tracked, when I realised that a carriage, like the one I downloaded from the web, is little more than a box with holes in the sides for windows, so it looked like an easy candidate for learning basic 3D drawing techniques.
To make it a bit more interesting, I went back to look at a carriage I had already constructed, using sides made with the Silhouette cutter. As one of my readers (Winander) pointed out, the prototype appears to have had rounded ends, which I had not been able to make, so I decided to see whether I could use 3D printing, to convert it to a more refined overall shape.
Model of early GWR carriage at North Leigh
I was especially interested to try the Autodesk ‘Fusion 360’ software, since it appears to be a comprehensive solution, aimed at becoming an industry standard, like other Autodesk products. Even more attractive is that the software is available free of charge, to hobbyists not seeking to make commercial projects.
Quite early on, I came across a web video that described how to make an electrical junction box with 'Fusion 360' but then I couldn’t find it again, after a period spent on other things! Such are the problems of short-term memory becoming less reliable with age.
Instead, I started to look at some of the Autodesk training videos but, perhaps I started in the wrong place, as I didn’t find them very helpful in deciding where to begin – there seemed to be an endless array of tools and techniques, and I had no idea which of these might be useful to me in the early stages. I came close to giving up on the whole idea, thinking the ‘learning curve’ was too steep for me but, then, I suddenly found that simple introductory video again and things started to feel possible, once more. In fact, this video by Lars Christensen, on the web at https://www.youtube.com/watch?v=A5bc9c3S12g proved to be the turning point, which convinced me that I really could get going with the Fusion 360 software! There are 3 episodes, which cover the basic principles involved in making a box-like structure, with curved corners and various penetrations through the walls
3D tutorial example
To cut a long story reasonably short, I learned from these videos that the starting point is to lay out a 2D plan on one of the three planes defined in the software. In the case of my basic carriage, this was just a rectangle, representing the floor. Even with the help of the videos, and after writing copious notes, it still took me a while to grasp the basic concepts behind the 'Fusion 360' user interface. Because it is such versatile software, there are many different modes of operation and, for my task, the first selection to be made was to choose the ‘Model’ environment from the top-level menu. I also set ‘mm’ as my dimensions parameter. The following screen-shots show the steps I took, following the Christensen video:
Steps in making a carriage body with 'Fusion 360'
Even while selecting these images, I had to go back to check some of the steps, where I couldn’t remember exactly what to do. The big difference in computer modelling, as opposed to ‘real’ modelling, is that no ‘bodging’ is allowed – you have to specify each step in strict accordance with the program requirements!
After following these steps, I had a box of the same dimensions as the coach I hope to build. A feature of the software is that I could paste a 2D DXF file, which I had already created for my Silhouette model, onto the appropriate faces of my box. With the image in place, I could then select the window openings and the droplight recesses, and use the PushPull tools to open up the apertures in the sides of the box, as described before. In this case, I used the inside face of the side as the depth reference point.
Using parametric references means that the windows will still penetrate the width of the side, if I subsequently decide to change this width parameter.
Importing a DXF file into 'Fusion 360'
That’s as far as I’ve got, at the moment. I hope that the techniques I’ve learned will ‘stick’ in my memory but I now have a written guide, to help me when needed!
I’m especially pleased to have found that that I will be able to use my existing collection of carriage drawings when creating new 3D models on the same basic principles.
Basic 3D carriage model
Of course, there are lots more components to add : interior partitions, seats, external mouldings, and so on, but I have reasonable confidence that I know enough of the basics to be able to make these additions relatively easily.