Computer-aided Design

Week 3

Introduction

Introduction

I drew a quick sketch in Inkscape, built a tiny model of my internal mechanism with LEGO and tried Fusion 360 for the first time.

Read on! Download fusion 360 file of project

Stepping stones

Finding my way through winding paths

Inkscape

Inkscape is the vector graphics illustration program I am most familiar with. I imported my concept drawing to Inkscape and used "trace bitmap" to convert it to vector format. I then drew a better concept of what I want the profile of the Will o'the Wind to look like.I also drew it from the top, to get an idea of the relationship of the blades of the turbine.

The biggest challenge at this stage was to wrap my mind around the internal mechanisms. Knowing their dimensions will be essential to designing the exterior as well. The biggest challenge later was to describe this process beyond what I already did in the above paragraph.

I could see no reason whatsoever to save the original svg for this image, so I had to redraw it later because for some reason I can't graduate unless I showed you the extremely boring details of how I went about using a program I use every day.

Inkscape step by step guide on how to draw a very simple image in Inkscape. WOW! Brand new original svg file, BAM!

Using LEGO to visualize my concept

I wanted to get a better feel for how the internal mechanism works, so I built the core of the model out of lego, to which I taped magnets. I considered winding copper wire around it, but decided against, since it seemed wasteful at such an early stage.

The benefit of this approach is that it's safe, which allows me to focus more on design aspects than on learning new terminology and keyboard shortcuts.

Youtube video about making a small generator

Instruction videos!

Luckily for me, there's about a million excellent instruction videos for Fusion 360 beginners. I watched this video which Linda Wanders shared with our Facebook group. I also found a series on youtube called Fusion 360 for absolute beginners which was very helpful.

Youtube video on parametric design Youtube videos for absolute beginners Fusion 360 for students

Initial Design

I used the center circle tool to create my first pieces, using measurements of some of the magnets available to me to create the mag unit. On top of the mag unit I used "create: thread" for fastening it to the turbine. I then crafted the coil unit around the mag unit, so that they would fit around each other with 1 mm of space between. This should allow the mag unit to rotate freely. To be added: Bearing for mag unit!

Thingiverse tutorial on slew bearings

The first turbine design

This was the first version of the assembled four pieces. I used joints to make the turbine and mag unit rotate. I grounded the shell, so that I could rotate the other pieces at will. I cannot even describe how happy I was when I pressed "animate" and it actually spun!

My turbine design is derived from the design developed by Icewind, an Icelandic company that specializes in small scale wind power in Icelandic conditions.

My first attempt was far too slender and not curved enough.

Icewind

Turbine v.2

I redesigned the turbine to make it more dynamic. I drew the outline from the side, the used "revolve" to make a circular shape around my center axis, which was a construction line I drew earlier. Then I tilted my view to look at it from the bottom, and drew two differently sized circles, their center points 5mm apart, under the base of my shape. I "extruded" the area between the two circles upward and used "intersect" to create the shape.

The wing was not aligned with my central axis, so I used the "align" tool to align it properly. Then I could use the "pattern" tool to create two more wings, distributed evenly around the central axis.

Video on terminology

Animating the model

I used the join function to create a rigid joint between the turbine and the mag unit, since they should spin together. I then grounded the shell, and created a revolve joint at the central axis of the turbine and the shell. Embarrasingly, I discovered later that it's spinning the wrong way!

To record my screen I activated the xbox screen recorder included in the default Windows 10 installation. To do so, one needs to log in to the xbox app, open the program (Fusion 360 in this case), and hit the windows key and G. This opens a handy toolbar for recording, and the video can be trimmed in the xbox menu. It is intended for streaming gaming videos, but works for other applications too.I also tried Camstudio, but it was very laggy and buggy on my computer, and the videos were in poor quality compared to the xbox recordings.

Guide to using the xbox recorder

Fixing the revolve joint to spin counter-clockwise

Of course, I could have just loaded the video in reverse and left it at that, but I decided to look up my issue, and the fix was relatively simple. When creating the joint one needs to keep an eye on the little flag that indicates the default revolve direction.

After fixing the revolution direction I rendered my model in Fusion 360. I changed the material, the color, and just for fun, I put in a background and some lighting. I also used Inkscape to make a logo to use as a decal on the rendering. The whole process was surprisingly straight forward. My only issue was an incomplete component. Until I removed it, my model couldn't be rendered.

I learned nothing new, because this was just a modelling exercise

I already knew these simple things and was focused on developing my design!


Instructions for Windows

These instructions are written assuming you have a Windows computer, a keyboard with no keys missing and an ordinary mouse with two buttons (It is alright if your mouse has more buttons, it just can't have fewer buttons). If you have any other type of configuration, seek help elsewhere, in the millions of tutorials which already exist for beginners and more experienced Inkscape users alike.


Opening Inkscape

To open Inkscape, press the Inkscape logo. You need to move your cursor over the logo that looks like a diamond-shaped ink-stain, then click with the left mousebutton. If you click with the right mousebutton, a menu will open, but don't worry! You can move the mouse and select "open" and Inkscape should still open as normal.


Resizing the document size

To be certain that your image is a good size to put on your website, we are going to resize the document. Click "File" then move your cursor down several lines, to the third last line of the menu where it reads "Document Properties". Click, again with your left mouse button. This will open a new window.


300 height 700 width

In the new window, near the center, change the units to pixels and write in your preferred size. In my case, I chose 300 by 700, because why the heck not? (In the image the numbers are as they were before I changed them.) You may have to press "return" on your keyboard to make sure the resizing is applied. It is the big button on the right hand side of your keyboard. Once you are satisfied with the new size, press the small "X" in the corner of this window to close it. Be careful not to accidentally press the "X" on the big Inkscape window, because then you close the program and will have to start over from step 1! By gosh gully, how embarrasing!


Making a big rectangle

Select the rectangle tool, and draw a big rectangle by clicking on the page and holding the left mousebutton while moving the mouse. It can be as big as you like, as long as it is at least the size of your document. Go nuts! If you were to hold the "ctrl" button at the same time as you were drawing the rectangle, the tool would automatically help you make a square instead. That does not suit us at this time, but is useful for future projects.

Now, at the top of the window, there is a toolbar. Select "Object" then select "Fill and Stroke". "Object" is a drop down menu that deals with objects on your screen. "Fill and Stroke" allows you to decide the Fill and the Stroke settings for your selected component. This will open a new panel on the right hand side of your screen.

Did you know? Objects and Paths differ in the way the respond to commands, and in what sort of options we have regarding editing and configuration. If you are feeling brave, try playing around with some of the differences between the two.


Changing the color

The Fill and Stroke menu has several options. First, select the "Fill" view. Make sure that your object is still selected in order to edit it. Select the square next to the "x". If you hover over it, it will read Flat Color, and if you select it, you get the view furthest on the left of the current image. Move the bars until you have the color you want, but make sure that blur and opacity are at 0% and 100% respectively (as they are in the image).

Now, select the middle tab of the Fill and Stroke menu, labelled "Stroke Paint" and press the "x" because we do not give to shakes of a rat tail about the stroke paint on this rectangle.

The third tab would allow us to edit the Stroke Style of our object, but since we elected to omit the stroke altogether, we have no use for editing it at all. Therefore, it is greyed out. If at any point you deselect the rectange, simply click it again in order to continue editing it.


Import your image

Select "file" and move your cursor down several lines, but not as far as before! Now, we will select "Import...". This will open a folder view, and you will have to find the image you wish to import. It is recommended that you save your images with distinctive names and in specific locations where you can easily find them. Once you have found your image, click it, select "open" and when a small menu pops up, just press "okay" without reading what the menu is about." Let's be honest, if you need the guide I'm writing right now, those options aren't relevant to you at this time.


Trace Bitmap

Select "path", then select "Trace Bitmap". This opens a new window. Make sure you have your image selected. Now, because my image is not very high quality, is dark and has shady areas, I had to play around with what sort of trace to use. In the end, I used the "Multiple scans" and "colors" to create several layers of paths. I then ungrouped the paths (CTRL-SHIFT-G) and deleted all the ones I did not want to use, leaving me with a rendering of my drawing which I could now configure to my liking.


Cropping the image

Now, draw a circle over your image. You do this in much the same way as when we were drawing the rectangle, except this time, you select the circle icon, and you hold the "Ctrl" button in while drawing the circle, which makes it a perfect circle. Select the arrow tool, then move your circle into the position you want.

Select both the circle and your image at the same time, either by drawing a big selection rectangle around both of them, or by clicking one, then holding "SHIFT" while clicking the other. Now click "object" hover over "clip" and select "set" If you followed these steps carefully, you should now have a much smaller image, with only the parts on it that you want to use.


Drawing a new circle and adjusting layers

Now, draw a new circle, just like before, and set the color to one you like. If you get confused, reread the previous steps on how to draw a circle and how to adjust the color. When placing the circle on top of the image we just cropped, you may notice that our image disappears behind the new circle! Don't worry though, it is just hidden, and we will bring it to the front so it will be visible again.

Right below the toolbar with "object" and "path" there is a secondary toolbar with little icons. Try selecting an object, any object. Now play with these buttons to move your objects forwards or backwards in relation to other parts of our work area. Stop when the rectangle is at the back, the circle in the center and the cropped image at the very front.


Freeform Drawing

The rest of this super simple 2D model of my final project which took me half an hour to draw, and now three hours to describe in achingly meticulous detail, is drawn using the various drawing tools available in the menu on the left. Experiment and have fun! Try making a circle, placing a square on top, converting both to paths using "Path"-"object to path" then cutting one with the other by selecting "path" - "difference".

Truly, the best way of learning how to use Inkscape is by using it, playing with the different options and learning how they relate to one another.

Conclusion and discussion

. Fusion 360 is a very powerful tool for creating models. It is also very helpful to create this sort of model to further understand your concept.

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