Using Cad
How to use Fusion 360 to design foam planes
Welcome to my tutorial on using Cad for model planes! To do this, you will need Fusion 360: https://www.autodesk.com/products/fusion-360/personal and Inkscape: https://inkscape.org/
Before taking on this tutorial, I'd recommend being at least a little knowledgeable in Fusion 360.
Just search for tutorials on youtube, and completing 5 or so will get you started.
Once you've downloaded and installed both programs, it's time to start.
First, open up Fusion 360.
It will look like this:
Some general information:
saving
you can save by clicking the hard drive symbol i the corner
change the default units
you can change the units by expanding "document properties" in the object browser and changing the object labeled units. (double click on it to change the value) (you'll want to set them in millimeters)
Ignore the timeline at the bottom and the name of the project at the top.
To name your project, go to file -> save as, and when it prompts, type the name of the project. In fusion 360, your edits get captured in the timeline, and you can go back in time and add edits, rearrange the order of things you did, and change the values you put into things (ie, go back in time and make an extrude have a value of 3 instead of 4)
The next step is to create a parameter called foam. In Fusion 360, parameters are variables that you use so that you don't have to type the same numbers over and over again. Another reason to use parameters is that whenever you want, you can change them, say, make foam 6mm instead of 5mm, and the design will automatically make all extrusions, thicken or anything that used foam correct to 6mm.
When the Change Parameters window opens, expand the User Parameters tab, and click the little plus sign. Then fill out the information as shown.
Next, you can import your plans. On the toolbar, click the "canvas" icon. It will then prompt you to choose an image. Select "choose an image from my computer"
After that, select a plane and scale it big enough to see properly. Then click ok on the right.
I'm using plans I drew up in inkscape, but you'd probably be using balsa plans you found.
The next step is to calibrate the image. In the object browser, open the canvases tab and right click on the canvas you created. Select 'calibrate" from the drop-down menu. Then click one point at the nose of the plane, and the next at the tail. Next, enter how many millimeters you want your plane to be. You can also measure the wing on the plans if you have a specific wingspan in mind.
Once all of this is done, it's time to get modelling!
To create your first former, you have to create a fusion 360 "sketch" of the shape. First, click the "create sketch" button in the top left corner. Then select the same plane as your plans.
Use the "spline" tool to create a curved shape on the sketch. Remember, if you mess up, there's always cmd-z.
Try to only sketch one half of the former, but it's ok if it isn't perfect. Fusion 360 makes it really easy to fix things like this.
When you get near the bottom, a blue dashed line will appear, your cursor will snap to any point directly below the top point of your spline. It's really helpful to line things up with this tool.
Once you're done sketching, click the check mark that will appear, or right click and select "ok" in the pie menu that will appear.
Or:
Once that's done, you can adjust the positions of the points and their effect on the line with the handles. Play around with it and see how close you can make it to the real former. Next, it's time to mirror the line.
Click the polyline tool and add your first point exactly at the top, where the line for your former starts. It will snap into place. Bring your cursor down to about the bottom of the former, it's not critical, and make it so the line is roughly vertical. it should snap into place.
When the line has both points on it, you can finish like you did in the last step. Click the green chack mark or click ok.
Please ignore the fact that I've moved to a different plan. This one will let me demonstrate more features.
The process is the same regardless of which plan you use.
Select your vertical line, and click "x" to make it a construction line. It will have no effect on the drawing, besides being an axis to mirror on. It will become dashed.
The next step is to mirror the former, so click the mirror tool on the top, and select your spline, then click on the "mirror line" box, and select the vertical construction line.
Click "OK" to confirm the mirror.
What's cool about the mirror tool is that after you mirror the spline, you can adjust one side, and it will automatically adjust the other one.
It should look like this:
If you click inside the field, then it should turn blue.
If not, adjust the top & bottom of the spline until they line up and the face is closed.
Repeat the above step for every former you want to model.
Click "Finish Sketch" in the toolbar to finish the sketch.
If you ever want to come back and change something later, just double click on the sketch feature in the timeline. You can then edit the sketch like normal.
Finishing the sketch
Editing it later.
With the face selected, press "q" to extrude the face. Then type "foam" into the box. It should autocomplete when you type "f". Hit "enter" and then select "New Body" from the drop down menu at the bottom.
After your first extrude is done, the sketch will automatically go invisible. You can toggle it's visibility in the browser.
Click the eye icon next to the sketch. You can also double click it to rename it.
Extrude all of your formers that you drew in the sketch. You should have a set of them like this:
Next, look at the back where the formers are flush with the canvas. This will just make it a little easier to move them into place.
Now let's begin to use the move tool to move the formers into place.
First, click the move tool in the toolbar. It should prompt you to select bodies to move. Hover your mouse near the center of the former, the gizmo should snap in place. If you accidentally click on the wrong spot, you can press the set pivot button to redefine the pivot point. Lastly, you'll want to make sure that the move type is set to bodies and not components or faces.
Turn the former 90 degrees first, and then use the gizmo to move it into place. It will usually snap in large increments, so if you need more fine control over the location of the former, you can either zoom in or type in exact values on the keyboard. I find that typing a value in, seeing where the former is and adjusting it larger or smaller works pretty well.
Repeat these steps for each former.
You should end up with something like this. Make sure that the formers are centered around the canvas!
Next, we need to make doublers for all of the formers.
You can either right click on one of them and select "move/copy" from the pie menu, or you can select the move tool in the toolbar. Make sure the move type is set to bodies!
At the bottom of the box that appears, check the "Create Copy" box.
I can't provide a picture for the next part because the command key, which is used for the screenshot key combination will make the former go back to its original spot. Either way, it's pretty simple. Just start moving it to the back or front of the plane, and type your foam parameter into the box.
Repeat for all formers.
It should now look like this. In places where you think you need more strength, you can add three formers.
Next, create an offset plane from the last former.
Make a sketch that looks something like this on the offset plane. the exact shape doesn't matter, and you can always change it later. It should be about 15 millimeters in width.
Repeat these steps for all the skin sections in the nose that don't require formers. The more you have, the smoother your shape will be.
Now it's time to make the skins. We need to go into the surface workspace for this. You can switch to it with the tabs at the top.
First, you will want to turn of visibility for all the formers you are not lofting with.
For reference, you will loft between these edges for each set of formers.
You should have something like this. make sure to remember which sides you are lofting on.
