Liberal Arts Blog — Joints: Bolts, Rivets, Mortises, Tenons, Pegs — What Are The Differences? Who Cares? Who Should?
Liberal Arts Blog — Wednesday is the Joy of Science, Engineering, and Technology Day
Today’s Topic — Joints: bolts, rivets, mortises, tenons, pegs — what are the differences? who cares? who should?
Have you ever worked as a carpenter? made furniture? had a job in construction? Time to share the joy.
But continuity is key to the depth of thought and joy. So let’s begin with a quick re-cap.
Last time, the history and math of the evolution of the cross section and profile of the I-beam with a focus on the revolutionary work of Eaton Hodgkinson (1789–1861) and William Fairbairn (1789–1874) at Orrell’s Mill in England in the 1820s. Two weeks ago (2/26), the triple syzygy of Feb 28, 2025 (the planetary parade, Orion, and the Ramadan Moon). Three weeks ago (2/19) three devices used in measuring equilibrium — the spirit level, the plumb bob, and the framing square, three wonderful metaphors for how to find happiness (equanimity) in human life a perfect analogue of the principle of homeostasis more broadly. Four weeks ago (2/12) the miracle of phospholipid bi-layers and emulsifiers (how the impossible becomes possible, that is how the immiscible (unmixable) becomes miscible (mixable) as in salad dressing, mayonnaise, and peanut butter. The week before that (2/5) the miracle of water (the high polarity which enables hydrogen bonding which in turn makes DNA and proteins possible, and the specific gravity which makes for a stable internal environment allowing for basic metabolic processes and which on the planetary level permits the vast oceans to regulate the earth’s climate. The week before (1/29) we looked at the mystery of liquid mercury, the gaseous hormone nitric oxide and “amorphous” glass. The week before (1/15), “January syzygy” — the beautiful alignment of celestial bodies. And the week before (1/8), the wonders of the owl with their circular paraboloid faces that act like satellite dishes helping them hear so well they can detect prey under a foot of snow.
Whew! Now back to the business of the day — the differences between bolts, rivets, mortises, tenons, and pegs. What do you know about building structures that the rest of us might not but would delight to learn?
Experts — please chime in. Correct, elaborate, elucidate.
THE MORTISE (the hole) and TENON (the projection) , AND THE PEG (that secures them together)
1. Also called an “m and t” joint.
2. “One of the earliest mortise-tenon structure examples dates back 7,000 years to the Hemudu culture in China’s Zhejiang Province. Tusked joints were found in a well near Leipzig, created by early Neolithic Linear Pottery culture, and used in construction of the wooden lining of the wells.”
3. “Mortise and tenon joints have also been found joining the wooden planks of the “Khufu ship”, a 143 ft long vessel sealed into a pit in the Giza pyramid complex of the Fourth Dynasty around 2500 BC.”
They were also found in the Uluburun shipwreck (14th century BC).”
NB. Used in furniture making as well as ship-building.
BOLTS (removable, threaded) VERSUS RIVETS (permanent, non-threaded, deformed — giving it two heads)
1. “A bolt is an externally helical threaded fastener capable of being tightened or released by a twisting force (torque) to a matching nut.”
2. “The bolt has an external male thread requiring a matching nut with a pre-formed female thread.”
3. “A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the tail. On installation the deformed end is called the shop head or buck-tail.”
THE DEFORMING PROCESS OF A RIVET — MAKING IT TWO HEADED
THE EIFFEL TOWER HAS 2.5 MILLION RIVETS!!!
RIVETS ON A RAILWAY BRIDGE — is there a metaphor here? as in “riveting” (a film, a novel) how many rivets do you need to form a lasting relationship?
CONCLUSION; To peg or not to peg — that is the question.
Or is it — to bolt or to rivet — that is the question?
Or is it — how many rivets do you need to feel safe?
https://en.wikipedia.org/wiki/Mortise_and_tenon
https://en.wikipedia.org/wiki/Bolt_(fastener)
https://en.wikipedia.org/wiki/Rivet
https://en.wikipedia.org/wiki/Eiffel_Tower
QUOTE OF THE MONTH
“Make your own Bible. Select and collect all the words and sentences that in all your readings have been to you like the blast of a trumpet.”
- Ralph Waldo Emerson
My spin — then periodically review, re-rank, and exchange your list with those you love. I call this the “Orion Exchange” because seven is about as many as any human can digest at a time. Game?
A LINK TO THE LAST FOUR YEARS OF POSTS ORGANIZED BY THEME:
PDF with headlines — Google Drive
ATTACHMENT BELOW:
#1 A graphic guide to justice (9 metaphors on one page).
#2 “39 Songs, Prayers, and Poems: the Keys to the Hearts of Seven Billion People” — Adams House Senior Common Room Presentation, (11/17/20)
NB: Palestine Orion (Decision) — let’s exchange Orions, let’s find Rumi’s field (“Beyond all ideas of right and wrong, there is a field. Meet me there” Rumi, 13 century Persian Sufi mystic)
YOUR TURN
Please share the coolest thing you learned this week related to science, engineering, or technology.
Or, even better, the coolest or most important thing you learned in your life related to science and engineering.
This is your chance to make someone else’s day. Or to cement in your mind something that you might otherwise forget. Or to think more deeply about something dear to your heart. Continuity is key to depth of thought.
