What is the biomechanical motion to draw a straight vertical line?
To draw a straight horizontal line I basically pin my elbow and then move across the page from left to right. Easy. I can hit my marks consistently and everything is good.
Vertical lines however I really struggle with.
What is the arm and wrist movement I should be striving for to get better straight vertical lines?
There's one trick about motion for drawing straight vertical lines which makes it easier:
- the drawing tool should be leaned on your ring finger and rests on the recces between your thumb and index finger while supported by middle finger and blocked with the thumb; the pinky is supporting the ring finger and index finger is not used at all. The palm top is slightly rotated to the down, so your hand is more "horizontal" (or rather top of the palm is a bit tilted tilted to the surface you draw on).
And there are a bit different mechanics for short and long straight lines:
- for short ones (not more than few centimeters) you use only the finger simultaneous movement, a bending moment into the palm. no wrist, no elbow no shoulder. Quick moves, hand a little suspended in the air or based on a surface (better for beginnings)
- for long lines: you have absolutely stiff wrist and fingers, the main movement is in your elbow and shoulder and must be paralel - if you are a person who keeps the arm close to the body it will be mostly the shoulder, if you are a "sweepy" drawer it will be mostly the elbow. In both cases avoid slow moves, but you'll see they are much slower than in the short line method.
Keeping the whole arm stiff will help in drawing clean lines. You should not rotate the paper or your torso to make it easier - it's a bad sloppy habit that would not help you in the future and the one that should be blamed for the misshapen and lopsided lines after you get used to it.
For the long lines: Keep practicing a simple exercise - for few minutes draw straight lines again and again in one direction, first the vertical or horizontal ones, then switch the angle and/or direction, and so on - a whole bunch of different angles with lots of lines; change angle/direction after you feel comfortable and steady for a moment or two with one. You should use the whole sheet of paper (the best would be sth like ISO A2 format). Repeat this exercice multiple times and you'll feel the difference. It's actually a very basic and popular exercise for beginners in the drawing courses for architecture exams (at least where I live). It's not only for vertical lines, but for straight lines and directional drawing in general, but improves the vertical lines the most.
If you struggle, don't do it. Rotate your paper instead. Draw all your lines at an angle you are comfortable with. I draw all my lines at roughly the same angle. I remember it being difficult doing this when I started, especially when working with a lot of line work, but it becomes second nature.
A few pointers for drawing straight lines in general:
- Don't use your wrist. Use your whole arm (from the elbow is OK, from the shoulder is better).
- Draw your lines at an angle that is comfortable to you. This is probably not going to be at 90 degree angles. Probably closer to 60, but whatever works for you.
- Push lines and Pull curves. Your wrist will naturally curve when drawing towards yourself, so use that when drawing curves, and do the opposite when drawing lines. Lock your wrist and draw away from yourself. (not everyone agrees on this one)
- Draw between points and focus on the end point. Don't look at the line you're drawing, just focus on the point you're drawing to.
- Draw in one fluid motion. Don't hesitate and don't stop to correct a mistake, commit and draw your line in one continuous and steady motion.
- Practice. Draw two dots and draw a line connecting them. Do this a few hundred thousand times and it becomes second nature. It's a good idea to do this a few times just before you start drawing.
Or use a ruler.