I used 2D CAD design and laser cutting to create the main structure of my station building based on Lyme Regis. As the model was nearing completion I started to look for the parts needed to finish it. Scale Link do white metal castings of ogee section guttering and packs of stop ends, corners, etc., plus a pack of clips, which can be used with 2mm plastic tube to make the downpipes. However, they do not make the 90° drainpipe bends which I needed for this model.

From the SW Circle drawing and from the photos in Branch Line to Lyme Regis, I found that I also needed four stovepipe chimneys with conical cowls and I could not find anything suitable on any of the Gauge O suppliers’ web sites. Neither did I possess a lathe, so I could not turn the parts. I had previously purchased 3D printed track chairs designed by Guild member, Dave Rayner. The parts were manufactured for him by a firm called Shapeways and the quality was good. As the parts I needed were not particularly complex, I decided that I would try 3D design for the first time and, if that worked, have the parts 3D printed.

I had taught myself to do 2D CAD drawing, but I had never attempted 3D CAD and I was worried that this would be far more difficult. I tried designing the parts using two different software packages. I still had AutoCAD which I used before I retired. If you can access this through your work or a friend in your modelling club, then this is a very flexible package which is capable of creating any engineering design you are ever likely to need.

However, I realised that most members would not have access to AutoCAD which costs thousands of pounds to buy. After some research, I found some excellent free software on the web called Sketchup. I designed and made the chimney in both Sketchup and AutoCAD and found the design process much the same. It was quick and easy with both software packages to design this simple part. Some command names are similar and some differ between AutoCAD and Sketchup. For example, both use Line, Circle and Arc, but Autocad uses ‘Path’, while Sketchup has a similar command called ‘Follow me’. However, as you are only likely to use one of these software packages, you will only need to learn one set of commands.

Another Guild member, Tony Heselden, has designed a range of trucks and buses for his layout and for this he used Sketchup. He also used Shapeways for manufacturing and now sells the models he has designed under the name of 1:43 Transport Models. He said that he had no previous experience of CAD and it shows the power of the software that such complex models can be designed by someone new to CAD. Tony commented “I found Sketchup reasonably easy to understand and I made use of the additional free “Plug-ins” that are available, which simplified some of the tasks”.

Another software package which might be worth trying is TurboCAD. At the time of writing, Maplin have been selling TurboCAD 16 Deluxe for £7.99 (this is an earlier version of this software, as the current version is v20). This has been used by other Guild members for 2D CAD design for laser cutting and chemical etching. The software also has 3D capability, so is another cheap software package with which you could experiment.

Everything you need to learn to create models using this type of software can be found on the web, or in the built-in help in each software package. On Sketchup’s main web site (see reference on page 31) click on ‘Learn’ and then choose Video Tutorials, which will take you step by step through the various stages needed to create a drawing. There is also a link to a Forum where you can ask questions if you have problems. In Sketchup you can also print out a Quick Reference Card, which is an easy way to remind yourself of the commands you need.

For AutoCAD, the best free tutorial I found is listed below in the references. This link will take you direct to the first lesson and from here you can link on to the other lessons, or back to the menu. You will not need to read all the lessons, as you do not need to create materials such as brick or wood or map them on to the object. Our output will be a 3D print file, not a photorealistic image.

AutoCAD also has a Forum which helped me on the occasions when I was stuck. Sketchup has built in tutorials and AutoCAD has built in Help, both of which are directly accessible from the drawing page.

It took me less than a day to view each set of tutorials and to start creating drawings. Although this was my first experience of 3D, I was able to create the chimney in both packages within a couple of hours. The pipe bend took a couple of evenings to create in AutoCAD, from first starting the drawing to having a finished file ready to download for 3D printing.

There are several ways to create an object in 3D. You can draw a circle or a rectangle and extrude it. That makes a tube, or a box. You can also modify the extrusion process to make a conical shape. Or, if I were trying to create something like a roller track gauge, I would draw the outline shape as viewed along one edge and then rotate this line about a central axis to create the required circular shapes.

For the pipe bend, I needed a circle extruded, but not along a straight line. It had to be extruded along an arc. To do this, I created the path, an arc, and then placed the edge of a circle against this arc and extruded the circle around this curve. This uses the Path command in AutoCAD, or Follow Me command in Sketchup. You can also subtract shapes, or press a shape into a surface to make the holes which are needed at the ends of each pipe.

Once you have made all the individual parts they are joined together to make the complete component. The pipe bend is made of an end, duplicated and rotated, and the curved centre piece. I then added a short length of pipe to hold it on to a sprue. The minimum diameter for this joining piece is 0.5mm for very small parts, or at least 1mm for larger parts. You then duplicate the component to make the quantity you need, using the Array or Copy commands, and finally add a sprue to join them all together.

Drawing of chimneys on their sprue

On the drawing packages it is vital that you set the resolution high enough to get smooth edges. You do not want a multisided polygon instead of a nice curved surface. This is covered in the Sketchup tutorial on circles and polygons and, for a smooth tube you should set the number of sides to 256. In AutoCAD I set the sides to 1000.

In both programmes, when you view the image on-screen, particularly in wire-frame view, it will be displayed with far fewer sides to reduce the processing load on the computer. Do not worry. Provided you have set the number of sides as above, it will print correctly.

The 3D printer needs a special type of file. In Sketchup you create this by going File > Export > 3D model, and then you can save the file in Collada (.dae) format, which the 3D printer will be able to read. In AutoCAD, the same command is Output > Send to 3D Print Service > Print

I am sure there are many good 3D printing companies, but I used Shapeways, as it is organised to accept drawings from individuals and to make the small quantity of parts we need. If you wanted a large production run then 3D printing would be an expensive way to create your parts, but for a small run it is cost effective. However, even if you are going into production, 3D printing is a good way to check your design and the prototype could be used as a mould for casting (but see later comment on this).

When you first go to Shapeways’ web site, have a look at the various menus. You will see the wide variety of objects which users have created and the many materials which are available, from springy plastic to shiny metal. Near the bottom of the site, you can click on Help > FAQs and there is lots of information on design, materials, costs, delivery, payment, etc. There is a link to Tutorials via the Help button and, once you are a Shapeways’ member, you can send a question to an engineer, or ask a question on the Forum.

Having joined the site you can make or buy parts. You will find a link: Turn ideas into real products > Create yours now. Click on this and you will find the whole process explained. In essence, all you have to do is download your Collada file, select the material and then order the print. As soon as you have downloaded your drawing file, Shapeways will automatically verify that it can be made. If the part is too small, too large, or has other errors, the system will inform you within a few seconds that the part cannot be made. You may be able to work out the problem yourself, or you can post the design on the forum and ask for advice there.

One important thing to note is that each dimension of your model must be at least 2.5mm, so an item 10 × 5 × 2mm would fail. However, even if you are creating tiny parts, provided you put them on a sprue it is easy to get over the minimum size requirement. The maximum size Shapeways can print is 700 × 380 × 580mm, which should be large enough for any part we would want for O-gauge models.

The price of your model depends on the volume of material used (not the ‘box’ volume), plus a handling charge and tax. The quoted price includes shipping and VAT is added at checkout, depending on the country of delivery. On a larger model, material costs can be reduced by hollowing out the centre of the model, but it is recommended that you include at least two drain holes and make these large enough to clean the wax out of the interior easily. I found it worked out cheaper on small items to include more parts on each sprue. For example, eighteen components on one sprue cost 40% less than if I had bought the same components as three sets of six parts.

Under Help, or via the FAQs page, you can access information on all the materials that Shapeways offer. These include metals and a wide range of plastics. For the plastics which we will mostly use, there is a trade off between price, fineness of detail, strength and smoothness. On the Materials page you will find a link to a comparison sheet and, from this, you can look at a detailed specification for each material and design guidelines, such as minimum wall thickness.

Once you have ordered the part, Shapeways make a final manual check that the part will manufacture satisfactorily, then the parts are made, and delivery is typically around two weeks. If you are happy with your model and you think it would be useful to other modellers (or if you want to set up in business) you can make your models available to all Shapeways members. You add a description, key words and what mark-up you want on the Shapeways cost price and you then make the parts available for sale. There are guidance notes on the Shapeways web site explaining how to set up your ‘shop’, but one thing to note is that the mark-up is a cash sum in euros or dollars, not a percentage. To give an idea of costs, in my shop six of the pipe bends or six chimneys retail at around €7 (£6).

As part of the manufacturing process, when the parts are delivered they have a fine film of waxy coating, which it is essential to remove before painting. One of the best ways to do this is to use an ultrasonic bath (I believe Maplin also sell these). But my method is to clean the parts twice by brushing with an old toothbrush in white spirit, followed by a rinse in water with a drop of washing up liquid and then another rinse in clean water. The parts are clear plastic, so make sure you do not lose any down the sink when you are rinsing. You can guess how I learned that lesson! The ultra-detail parts are made in an acrylic polymer and can be stuck together with any glue which will stick hard plastic, such as superglue or Evostik.

One alternative to Shapeways is 3D Creation Lab. This company offers 16 micron resolution for its 3D prints compared to, at best, the 27 micron resolution of Shapeways. Unfortunately the trade-off is that the cost is much higher. If you are directly printing the component then you will probably find that Shapeways quality is sufficient and the low cost makes it worth trying them in the first place. However, other Guild members have found that Shapeways is not good enough for making the masters for silicon rubber moulds. The rubber tends to ‘grab’ the irregularities in the 27 micron surface, whereas the 16 micron prints did not cause any problems.

3D drawing is not very easy, but neither is soldering, or turning, or any of the other dozens of skills we use to create the models we desire. Like most skills, you need to read the tutorials, work steadily through the process and, above all, have patience when it does not work first time. Every time I have been stuck, I have found the solution either by having another look at the tutorials, or by going on the forum. The part of the process I personally found most difficult was locating the various elements in space and making sure that they are mated together correctly. But the great thing with drawings is that you can try something, then view the model from various angles to make sure that it is correct and, if not, you just click Undo (Sketchup: Edit > Undo) and have another go. It’s a lot easier than un-gluing, or scrapping your part-built model.

In a few hours, these programmes have enabled me to create parts which would have been difficult to make. The alternative way of making the 90° pipe would have been to try to bend 2mm pipe to 2mm radius and to then attach more tubes for the pipe joints, with flanges cut out of styrene. Not an easy task and I know the results would not have been as good.

I have found that 3-D print quality is good and the price is reasonable for small runs, so I hope my experience will inspire others to have a go at making their own models and components. Other Guild members have used CAD drawings to create designs far more complex and impressive than mine, so I hope they will also find the time to share their expertise and experience with us, either through the Gazette, or via the GOG Forum.

I would like to thank John Birch and Tony Heselden for their helpful input to this article.

• Sketchup 8: http://www.sketchup.com/products/sketchup-make
• Sketchup Plug-ins: http://extensions.sketchup.com/
• Sketchup Plug-in Reviews: http://sketchuppluginreviews.com/
• AutoCAD tutorial: http://www.we-r-here.com/cad/tutorials/level_3/3-1.htm
• AutoCAD forum: http://www.cadtutor.net/forum/forum.php
• Shapeways: http://www.shapeways.com
• Dave Rayner’s Off The Rails shop: http://www.shapeways.com/shops/otr
• Tony Heselden‘s 1:43 Transport models shop:
• http://www.shapeways.com/shops/shapeways.com/shops/1.43transportmodels?s=0
• My shop on Shapeways: http://www.shapeways.com/shops/O-gauge-supplies
• 3D Creation Lab: http://www.3dcreationlab.co.uk/

For other references and links please see the first article in this series, Vol. 19 No. 1, which was on 2D drawing and laser cutting.

Making your own laser cut models