Translations:Engine Block Tutorial/51/en

From FreeCAD Documentation

Now that we have our guide polygons in place we are ready to draw in the spline curve defining the outside shape of the engine block. Since this curve will be part of the final object you can turn off construction mode by clicking the same button you pressed to turn it on. Now click the Add BSpline button () and start drawing the BSpline by CTRL+left clicking on each place you want to add a control point for the spline curve. You will want your first control point to be on the leftmost point of the inner guide polygon for the left cylinder. Continue adding control points all along the spline curve until you click on the last point before the one you started drawing, then click the Close button up where you typed in the position and radius for the 2D circles we drew for the headbolts. Clicking this close button finished drawing control points for the spline curve and joins the ends together to form a closed loop. It is very important that you properly close loops like this if you plan to extrude them into solid objects like we will be with this one. For open spline curves you can just click the Finish button instead of the Close button when you are finished drawing. To the right you can see what you finished spline curve should look like just before you press the close button (notice I have drawn all but the last line segment and my mouse pointer is just about to click the Close button to finish the spline curve). Also notice that I have checked the Filled box so the resulting spline curve will form a solid sheet, rather than just an empty ring, this must be done to extrude it into a solid shape that is capped on the ends.