UNIT 4: ENGINEERING CURVES: OVALS, OVOIDS AND SPIRALS

 ENGINEERING CURVES:

 OVALS, OVOIDS AND SPIRALS

The links between circumferences have a direct application in the construction of technical curves such as the oval, the ovoid or the spiral.

The oval is a flat and closed curve, symmetrical with respect to its two perpendicular axes and formed by four equal circumference arcs two by two.

The ovoid is a flat and closed curve, symmetrical only with respect to its major axis, and formed by four arcs of circumference, of which two are equal and the other two are unequal.

The spiral is a flat, open and continuous curve that is configured by a point that moves uniformly along a straight line, this being fixed at a point through which it rotates with a constant angular value. 

If the spiral is generated by regular polygons, it is called a volute.

Now you will learn how to draw Ovals, Ovoids and Spirals. 

In spanish we call them "curvas técnicas". You will find that in english it is translated as either engineering or technical curves. 

Here are some video tutorials for you to practice at home: 

1- Draw an oval given the short axis CD.

2- Draw an oval given the long axis AB.

3- Draw an ovoid given the short axis AB.

4- Draw an involute of an equilateral triangle.

ACTIVITY EXTRA: THE FIBONACCI OR GOLDEN SPIRAL

LET´S GET ARTISTIC NOW...

TRIBAL AND SIMBOLIC SPIRAL PAINTINGS BY SAM BROWN

HERE ARE SOME OTHER ARTISTIC IDEAS BASED ON THE SPIRAL:

      

UNIT 2: VISUAL ART ELEMENTS VALUE "CHIAROSCURO DRAWING"

VISUAL ART ELEMENTS: VALUE

"CHIAROSCURO DRAWING"

- ART THEORY AND INSTRUCTIONS -

ELEMENTS OF ART: VALUE 

This is our next task. You will draw a sphere and also the value scale as you can see in the example.

MATERIALS FOR THIS ACTIVITY: Soft lead pencil (2B, 3B, 6B...) and your BASIK DIN A4 paper.

HB SCALE:  There are two graphite grading scales used to measure the hardness of a pencil’s graphite core as you can see in the image.Most pencil manufacturers outside of the U.S. use this scale, using the letter “H” to indicate a hard pencil. Likewise, a pencil maker might use the letter “B” to designate the blackness of the pencil’s mark, indicating a softer lead. The letter “F” is also used to indicate that the pencil sharpens to a fine point. Historically, pencil makers also use combinations of letters to tell us about the graphite — a pencil marked “HB” is hard and black, a pencil marked “HH” is very hard, and a pencil marked “BBB” is really, really black! Today, however, most pencils using the HB system are designated by a number such as 2B, 4B or 2H to indicate the degree of hardness. For example, a 4B would be softer than a 2B and a 3H harder than an H.

USED OF THE PENCILS ACCORDING TO THEIR LEAD: 

TECHNICAL DRAWING: HARD LEAD ("H" AND "F")

ARTISTIC DRAWING: SOFT LEAD ("HB" AND "B") 

 

 

THEORY 




VIDEO - TUTORIALS











ACTIVITIES

YOUR FIRST TASK: SHADING A SPHERE

YOUR SECOND TASK: SHADING AN OBJECT or CREATING AN OPTICAL ILLUSION. 

You can choose an object, a "still life" a body part or a landscape to practice shading, remember to use the "B" graphite pencils (the higher the number, the softer the lead). 









M.C. ESCHER 

M.C. Escher was one of the world’s most famous graphic artists. He created many visual riddles, and an amazingly detailed piece titled "Drawing Hands" that offers lots of detail.