Computer-Aided Design
In this week, I tried 2D and 3D design of parts of my final project. I looked several options of 2D and 3D design software and used Fusion 360 for 3D design and Inkscape for 2D design. I wrote basic functions in Fusion 360 that I learned and used and how I designed 2D and 3D model. I attached the files of them as well.
Yriö Louhisalmi, Fab Lab Oulu stuff and a student of Fab Academy 2017, gave local lecture about basic functions in Fusion 360. I have used Fusion 360 once, but I was not yet confident to use Fusion 360. Before I started working on the assignment, I tried several functions to get to know them.
There are shapes which can be the base of design, such as Rectangle, Circle, Polygon etc. These shapes can be combined and modified by functions such as, Fillet, Trim and Extend. It is also possible to insert vector image as SVG file.
There are two important functions to create 3D design from the 2D sketch.
Extrude is the function which gives a closed sketch profile. It is possible to select start point (profile plane, offset plane and from object), direction (one side, two sides and symmetric) and extent (distance, to object and all). This function is useful when you want to cut some parts or add height of a sketch profile.
Revolve is the function to make 3D model revolting around a selected axis. It is possible to choose how much does it revolve by setting angle or choose full. This function is useful when you create a circular body from 2D design.
Fillet function is for making intersection parts smooth by applying arcs of specific radius at a corner or edges. Shell function is to create walls on the object. It is possible to choose thinkers of the wall and direction (inside, outside or both).
I learned it is important to set parameters as much as I can before I modify or copy it. It is much easier later when you change the size of parts. According to the parameters, sizes of other parts will be changed automatically. To create parameters, MODIFY> Change parameters. To use parameters, SKETCH> Sketch Dimension.
It is possible to create work planes, axises and points. These functions are useful to edit or draw on 3D objects. There are many options to create them depending on the shapes of the objects, such as Midplane, Tangent plane, Axis through edges, point at centre of circle/sphere/torus etc.
Fusion 360 allows to create 2D design. I can choose the surface of a body and draw or insert vector image on the surface. It is useful, for example, when you create a 3D object and want to laser engraving on it. You can draw 2D design on the 3D model.
I designed a globe in Fusion 360. It is a part of my final project. I haven’t decided which technique I will use for making the earth yet, but as an experiment, I designed 3D model of the earth in Fusion 360.
There are two ways to make a globe: 1) wrap a 2D world map as a sphere and 2) extrude a 2D world map to the surface of a sphere. I searched what people have already done. As long as I searched, there is no way to design a 3D globe in Fusion 360. Fusion 360 doesn’t have wrap function, such as Cinema 4D has. There are unfold function in Fusion 360, but it works with only cylinder and doesn’t work with a sphere. So I chose solution 2.
Since I haven’t tried to insert SVG file in Fusion 360, I started experiment of inserting and extruding a world map on a flat surface. I searched a simple world map from the internet. I chose the map doesn’t have Antarctica to make it simpler as practice. I download it in my laptop. Next I import the map in Inkscape to edit the size and simplify the map by deleting small parts.
I opened Fusion 360 and selected SKETCH>Create Sketch. I drew a rectangle and selected STOP SKETCH. I selected CREATE>extruded to create a new body of the rectangle. I started new sketch, imported the map and placed it in the rectangle. I stopped the sketch, chose CREATE> Extrude, selected the map as a profile and selected operation as join. The map was extruded from the surface of the rectangle.
Next, I searched how to extrude a sketch profile on the sphere surface. This video shows how to extrude letters on the sphere surface and this video shows how to extrude letters on the cylinder surface. I combined these two techniques and managed to extrude the world map on the sphere surface. First I created a sphere. I identified a centre point by choosing CONSTRUCT> Point at centre of a circle/sphere/torus. I moved the centre point to origin. Next I split the sphere into half by the Y axis.
I started sketch on the XY surface and inserted SVG file of a simple world map. When I inserted the map I scale up it so that it fits on the sphere and moved the map to the location where the half of the map (Asia, Australia, Europe and Africa) fit on the sphere. I deleted another half and I stopped the sketch.
I chose CREATE> Extrude and selected all continents as profile, selected from object as start point, chose join and set distance as 3mm. Next I created a new sketch, inserted the same map, place the other half (North and South Americas) on the sphere and mirrored the map. I stopped the sketch and extruded the map on the other half of the body following the same steps. I have the sphere which has the world map extruded.
I am not satisfied the result of the 3D model of the earth because it is not accurate. The location and the size of the continents are not correct. I have three ideas to solve this problem: 1) calculate the size and XY ratio of the map carefully, 2) divide a sphere into four or more pieces and 3) try other software which has wrap function, Cinema 4D etc. I will go though the other 3D design software and other techniques.
I made 2D model of a part of my final project, orrery night lamp. It is a flat ring which has the name of each month on it. I want to make this lamp around 300mm width. So I decided to make outline of the ring 300mm, and it has a 240mm hole in the middle. I am going to make it with plywood and designed in Inkscape. Inkscape is vector based program which uses mathmatical calculations to draw in the program. The files are saved as, for instance, SVG or PDF format.
I drew circles in Inkscape. I drew four circles which diameters are 300mm, 290mm, 250mm and 240mm to create two different rings. The bigger ring made with 300mm and 240mm diameter circles will be the base of this model which will be cut out later, and another smaller ring which is made with 290mm and 250mm diameter circles will be engraved on the bigger ring with months’ names.
I designed the smaller ring first, which will be engraved later. The smaller ring will be divided into 12 sections and each section has a name of each month. To make the sections, first I drew a rectangle which width is 290mm and height is 0.5mm. At first I worked with lines to make sections, but I found out I cannot apply Union/ Difference functions on lines, they only works for shapes and areas. So I used thin rectangles instead of lines. I placed the rectangle in the middle of the 290mm diameter circle (Object> Align and Distribute). I duplicated the rectangle and rotated it 30 degrees. At first I cloned the rectangles but later I found out I cannot apply Union/ Difference functions to cloned objects because of the bug.
I repeated duplicating and rotating and got a circle and 6 rectangles distributed each 30 degrees. I selected all the rectangles and applied union (Path> Union). I applied union to 290mm diameter circle and merged rectangles.
Then I placed the 250mm diameter circle in the middle of the 290mm diameter circle and applied differences (Path> Difference). I got a 290mm diameter circle with12 sections.
I wrote the names of each month and placed it in each section. I selected them and grouped. I placed the 290mm diameter circles which will be engraved, in the middle of the 300mm diameter circle which will be cut out.
I tried GIMP to edit the image of world map to laser engrave on the sphere surface. It might be used for my final project. The difference between Inkscape and GIMP is the program is vector based or raster based. The lines of raster graphics is drawn as coloured pixels while the lines of vector graphics is machematically calculated and shown on the screen. So when a line drawn in GIMP is zoomed, many coloured pixels are seen. Raster graphic tools are suitable for photo editing or detailed images, while the results of vector graphic tools are more abstruct. The files of raster graphics are saved as, for instance, PNG or JPG format.
My plan for the final project is to laser engrave the world map on the sphere using rotary attachment. I read this instructions to understand the tips to engrave on the sphere surface. I downloaded the world map which looked suitable for engraving on the sphere. from this website To engrave the world map on the sphere, I needed to remove the background and change the image into grayscale. To remove the background I followed this instructions. To edit the image for laser engraving, this video explains very well.
I imported the image in GIMP.
I chose select tool in the tool bar on the left and drew lines around the parts that should be remained. To select multiple parts, press Shift and start drawing the line.
The dot lines appeared around the selected parts
Although I have used Fusion 360 and Inkscape before, I found many new and useful feature during the process. At the same time, I found limitations. For instance, there is no wrap function in Fusion 360 and Inkscape doesn’t allow to apply union/ difference function to cloned shapes. To solve those problems, I need to use other software or choose different methods. After using several different software for a while, I will get to know the specific features of each software and will have more options to choose for 2D and 3D modelling.
The following zip file contains the parts of my final project: Fusion 360 Archive File and stl file of the sphere with world map made in Fusion 360, svg file of the ring and xcf file of world map.