Three-D Modelling for Railways

You do not need to know this to do 3d printing, but you might just be interested. Just as background on what I know, I have a Ph.D. in chemistry, and did a lot of work on free radical reactions for my thesis, though not polymerisation. "Normal" Chemistry Virtually all the organic chemistry taught in an undergraduate course is about positive and negative attracted to each other, and pairs of electrons moving around. Electrons really want to be in pairs. When you look at the structure of an organic compound, each bond is a pair of electrons. Here is an example reaction. Each letter or pair of letters represents an atom, in this case hydrogen, carbon and bromine atoms. Straight lines between them indicate bonds - each line is a pair of electrons shared between the atoms at each end. Two straight lines together is a double bond, so four electrons. Chemists use curly arrows to indicate the movement of electron pairs. The H of H-Br is somewhat positive, and the double bond of ethen...

The Settle and Carlisle Railway was built be the Midland Railway to give them their own route to Scotland - as far as Carlisle anyway - so they were not beholden to the LNWR. At Carlisle, it briefly joined the NER line from Newcastle, before going into Citadel Station, which was run by the Citadel Station Committee (LNWR and Caledonian Railway), and then on to Scotland on the Caledonian. It opened to goods in 1875, and to passengers the year after. The line runs through some bleak countryside, with few towns, and post nationalisation it became more and more run down, and was threatened with closure when the Ribblehead Viaduct needed repairs. A public campaign dissuaded government, and it remains open, and has become popular as a tourist route. The bleak countryside makes it popular with modellers, and anyone doing modern day has a good excuse to run steam trains as they are (relatively) frequent visitors. Plus it still has semaphore signalling! From a 3d modelling perspective, the line...

I wrote about curves previously , but if your curve is a circle - or a section of a circle, an arc, - you have other options. Cylinder The most obvious is to just use a cylinder mesh. Remember to give it enough sides that it will resemble a smooth curve when printed. As a rough guide, at least 2 sides for every millimeter in the diameter. Too many, and you are slowing the computer down unnecessarily, too few and the steps will be visible. If you want a hollow cylinder, create two, one inside the other, with the inner one a bit longer. Then on the outer one add a Boolean modifier, and apply the inner one, I like to put all the meshes that are just there for Boolean operations into their own collection. You can then hide that collection, and see the hole. If you want a section of a circle, you can just delete the vertices you do not want, and add faces as required. However, if you have a move complicated shape composed of several concentric cylinder that gets harder to do, and you are be...

Castlefield is in the west of Manchester, and is home to some great bridges. Two canals meet here, and they were here first, so we start with them. The red is the Bridgewater, the first to be built, from coalfields in Worsley. It drew its water from the Medlock, in blue, which became increasingly polluted. When the Rochdale Canal arrived, the Bridgewater could gets its water from there. This necessitated building a tunnel for the river. Some sources indicate this used a siphon to allow the water to get back up to river level, after going deep enough to get under the canals. Further upstream, I guess it has just been culverted. The railways here are more complex - hardly unique in Manchester - due to the vagaries of history. This view is annotated with the lines, based on the Railway Clearing House map of 1910. The blue is the LNWR line from Liverpool, the original Liverpool and Manchester line. The station is now the Museum of Science and Technology. The yellow is rather more recent, i...