123D Design Tutorial: Alloy wheel or steering wheel

Before using these instructions, it is very helpful to watch this video screencast of the CAD drawing actually being done in the software. Click this link for the video instructions

Start in TOP view, and select ‘Sketch Circle’

Click on the grid to start sketching and click on one of the large square crosses for the centre of your circle.

Draw a circle 50mm diameter

Use Sketch Offset to draw another circle 5mm outside the original circle, so your sketch looks as below.

You will now start drawing the spoke sections of the wheel so that it looks like this Select Sketch Three Point Arc and click on your wheel to add to this sketch

Click to specify the start point – 2 small squares to the left of the wheel. Then the end point – make this 2 small squares to the right of the wheel

Drag the mouse along the arc until the

mouse pointer is one square above the centre of the circle, then left click once to fix this point on the arc.

Page 1 of 6

Diane Burton, STEM Outreach. [email protected]

Click on the same start and end points to draw the next arc so it mirrors the first arc.

Select the point on the arc one square below the centre of the

circle.

Now start the next arc 2 small squares above and below the circle – point on the arc, one square to the side of the centre.

Sketch the final arc

Your drawing will look like this.

Use Sketch Trim to remove the outer bits of the sketch so it looks like this

Use Sketch Circle to draw a 10mm diameter circle in the centre square. Your drawing should look like this.

Page 2 of 6 Diane Burton, STEM Outreach. [email protected]

Select Sketch Ellipse and click in the centre of this section – this will be the centre point of your ellipse shape. Left click one square along to show the axis point of the ellipse.

Then drag your mouse to specify the point on ellipse – you want this to be 2, type 2 in the box, left click and press enter.

Use Sketch Ellipse to put a matching ellipse shape on the other side

Use Sketch Circle to draw 4 circles as shown This one is 5mm diameter and this one is 4mm diameter. Note where the centre of each circle is.

Your finished sketch should look like this.

SAVE YOUR

WORK!

Select ‘Sketch Trim’ and click on the wheel and begin to trim the lines you don’t need as shown.

Your finished sketch will look like this.

Page 3 of 6 Diane Burton, STEM Outreach. [email protected]

Select the outer ring and use Construct Do the same with the inner part of the Extrude to extrude by 4mm height. drawing – extrude to 4mm height.

Select Modify Fillet and then click on the outer ring of the wheel – put 4 in the fillet radius box then press enter.

Select Modify Chamfer and click on each of the ellipses – put 1.5 in the chamfer distance box then press enter.

Select Modify Chamfer again and select each of the circle and chamfer by a distance of 1.

SAVE YOUR WORK!

Page 4 of 6 Diane Burton, STEM Outreach. [email protected]

Select Modify Fillet and then left click on each of the inner spoke edges in turn to select them. Fillet by radius of 1, then press enter to finish.

Your drawing should look like this.

Select the Pattern Mirror tool Select the wheel as the Solid (it highlights bright blue when selected).

Click on Mirror Plane and turn the screen to select the underside of the wheel.

The shape will mirror to produce a

duplicate shape – press enter to finish.

Your drawing will SAVE YOUR look like this WORK!

Add the centre solid piece of the wheel with a rounded top piece

Select Construct Extrude and click on the centre circle sketch - extrude by 5.5mm.

Remember that you extruded the rest of the wheel by 4mm, so the centre circle will protrude by 1.5mm (5.5 – 4 = 1.5).

Use Modify Fillet to round off the centre piece

Page 5 of 6 Diane Burton, STEM Outreach. [email protected]

Rotate the screen to look at the underside of the wheel and you will see there is a hole

(this is because you mirrored the wheel before you extruded the centre circle. You can extrude this

centre piece now by selecting Construct Extrude and clicking on the centre circle.

Pull the yellow arrow to extrude by how much you want. It will be a negative number as you are extruding downwards. -4mm will put it flush with the rest of the wheel, -2mm will leave an indent, whereas more than More than -4mm will leave a protruding cylinder that could be an axle or steering column.

SAVE YOUR WORK!

Click the drop down on the top left of your screen and select ‘Export STL’

Page 6 of 6 Diane Burton, STEM Outreach. [email protected]