It's been a couple months of chaos since my last installment in this intermittent series. I have located my pens and pencils, taken the time for some photography, and am now ready to start writing!

Board drafting is becoming a lost art, but most people are likely familiar with mechanical pencils. Have you noticed that some use 0.5mm lead, and others 0.7mm? Have you ever wondered why?

In drafting, there are a few basic standards for line weight, or thickness. Standards have changed over the years, but at present, mechanical drawings use thick or thin lines, while architectural drawings usually use thick, thin, and extra-heavy lines. A pen or pencil is held perpendicular to the paper so the full diameter of the lead makes a consistent line width.

These pencils include a 0.3mm (yellow), a 0.5mm (red), and a 0.7mm (blue). I also own a 0.9mm pencil (pictured in my Dividers and Compass post) that I preferred for heavy lines on architectural drawings.

Note the collars on the barrels. These can be used to select markings for different lead types. You are probably familiar with the classic #2 pencil, and that refers to the hardness of the blend of clay and graphite in the core. Harder lead leaves a fainter line, but is less likely to smudge and easier to erase. Softer lead leaves a rich, dark line that is easy to read, but is easier to smudge.

My 0.5mm is actually loaded with blue lead, because most large-scale document reproduction methods don't copy blue lines. No erasing is needed at all!

Here is a disassembled Koh-I-Noor Rapidograph drafting pen. This is a special fountain pen with a dip designed to dispense ink at a specific line width when a plunger at the tip is pressed to the paper. The nib can be further disassembled for cleaning with a special tool that was included in the pen set. The reservoir is filled with black ink, a color-coded collar secures the reservoir to the nib, and the barrel just makes the pen easier to hold. The caps have color-coded tops that match the collars and list both metric and traditional imperial size designations.

Some mechanical plotters used these pen nibs to automatically reproduce digital drawings using ink, but these are far less common nowadays. Drafting programs can still be set to assign line weight according to color to match these pens, too.

It goes a bit beyond the scope of this post, but I should note that tools like triangles, straightedges, and templates designed for professional drafting have small standoff bosses or a relieved edge that allows ink to flow without staining the tool or ruining the line being drawn.

Confession time: When I got these pens out for photography, I discovered that three of them had not been touched since my board drafting final exam cough years ago. Cleaning time!

I was given these old technical pens as a gift, and while they are also marked as Koh-i-Norr Rapidograph, they are mechanically very different. If I am not mistaken, the entire barrel serves as an ink reservoir, and the plunger mechanism somehow ensures proper ink flow or adds vacuum pressure to prevent leaks. Just guessing. I need to look up info on these. I found them while preparing this post, and thought I would include them despite my lack of knowledge.

I have never used this tool, but it belongs in this post, too. This is a ruling pen. I defer to Wikipedia for a more thorough explanation, but in short, a screw adjusts the spacing between the two leaves of metal to control the flow of ink.

I suggest browsing YouTube for videos showing how these tools are used in drafting and art. People with better videography and skill level there trump anything I could show here.

Previous posts

Lettering Guide and Eraser Shield
Scales
Dividers and Compass