This tutorial allows you to discover new Additive tools in FreeCAD Part Design workbench: Additive loft and Revolution. It also introduces the notion of Datum object to create new reference elements in a part.

1. ### Step 1: Presentation of the exercise

We are going to model the part illustrated below, using the method proposed in the construction tree.

For the dimensions of the part, you can refer to the drawing below but they will be recalled during the tutorial.

Steps 2 to 5 are not particularly difficult if you know how to read a drawing, create a constrained sketch and apply the basic functions. You can therefore try to carry out steps 2 to 5, illustrated below, without the help of the procedure.

In steps 6 and 7, we will see how to apply symmetry to our part, and then make cavities without producing new sketches.

In the last steps of the tutorial, steps 8 to 11, we will see some advanced Part Design concepts: Additive loft and Datum objects.

If you have no previous experience of 3D modelling with FreeCAD, I recommend you follow exercises 1 to 4, previously published here. Exercise 1, will give you an overview of the Part Design and Sketcher workflow, Exercise 2 will help you understand the concept of external geometry and Exercise 3/4 will give you additional tips.

2. ### Step 2: XY plane sketch - Pad

Draw the sketch: first the rectangle with rounded corners, then the geometric constraints of symmetry and equality and finally the dimensional constraints.

3. ### Step 3: Sketch Bottom Side - Pocket

Draw the sketch: you can use the external geometry to hang the rectangle.

Apply the Pocket function.

4. ### Step 4: Edge selection - Fillet

Select the edges.

Apply the Fillet function.

5. ### Step 5: Sketch Top Side - Pad

Draw the sketch: the circle is coincident with the horizontal axis.

6. ### Step 6: Symmetry along the YZ plane

Select the last Pad element in the tree structure and apply the Mirrored function, according to the YZ plane.

7. ### Step 7: Pocket from the faces

Select the two faces at the bottom of the holes formed on the top of the part.

Apply the Pocket function.

8. ### Step 8: Additive loft

Select the side on which to draw the sketches.

Draw a first sketch, which will be the base of Additive loft.

Exit the sketch and create a new sketch on the same plane. Then draw the second shape, which will be the top of Additive loft.

Exit the sketch. Click on the top sketch (Sketch 5) to access his properties, then put the attachment position Z to 140 mm.

Use Additive loft function to creates a solid by making a transition between the two sketches, Sketch 4 and Sketch 5.

9. ### Step 9: Datum line

Select face at the top of the Additive loft.

Use Datum line function to creates a line to be used as reference for sketches. In our example it will be used as revolution axis for Revolution feature. Mode of attachment in Task View : 1st main axis.

10. ### Step 10: Revolution

Create the sketch below at the top of the part.

Apply Revolution function of 360°.

11. ### Step 11: Pocket and Dress-up

Make the skecth below. External geometry is used to center the circle.

Apply Pocket function, "through all".

Apply Dress-up tool, to finish the part : Fillet and Chamfer. This will give a more realistic look to the part.

That's it, the exercise is over ! Well done and thank you for following this tutorial.