Beading Crimp Tubes and Monofilament

Tensegrity tools

Crimping tubes from the beading craft can be used for small repairs, construction projects, and some remarkable tension-oriented models. Beadalon’s crimp tubes are used to secure the ends of lines and to make loops of line. 500 of their #3 crimp tubes are available for about a two cents apiece. Small crimping pliers reliably pinch those little tubes. These crimpers put a notch along the center of the tube and then squeeze the two separate channels shut for a secure and permanent connection.

Beaders typically use these tools with thread or metal wire for their bead artwork; I prefer monofilament fishing line. Monofilament line has superior tensile strength; the line will stretch a bit under stress but will rapidly return to its original length. Fishing gear manufacturer Jinkai makes a variety of strengths of fishing line; their 50 lb. test line works perfectly with the Beadalon #3 crimp tubes. Jinkai also makes their own line of crimp sleeves (in 12 different sizes) for fishing tackle. While Jinkai’s sleeves are a bit more expensive, they are very strong: the largest sleeves paired with their strongest monofilament line has a rated strength of 920 lb. test.

Crimped monofilament line has all sorts of mundane use around the house. Packages can be sealed. Odd-shaped parts can be held together during construction/repair — or held together permanently. I recently fixed a portable fan by securing the halves of the protective screen together with a small loop in about a minute. If the excess line is trimmed with a pair of flush cutters, this kind of repair is elegant and professional.
The most interesting use I’ve found for the monofilament line loops is for high-tension tensegrity models. Many have created tensegrity icosahedron models (also called six-strut models) with rubber bands. The Skwish toy, an infant tensegrity-based toy, uses stretchy fabric lines.

Tensegrity is one of nature’s cool tools: structures can have rigidity when needed and fluidity the rest of the time. Floating compression is used for all scales of biological structure from the the cell’s nucleus to our musculoskeletal network. Biomimetic researchers are creating tensegrity-based robots. Swiss graduate student Sinan Korkmaz has created a tensegrity bridge which can sense its load and alter the tensions (thus the behavior) of the structure on the fly.

Kenneth Snelson invented tensegrity models over 60 years ago; Fuller’s Synergetics was published in the mid-1970s. Nature uses tensegrity everywhere, but the structural dynamics remain elusive to most of us. That will continue until many people get hands-on exposure to these remarkable models — especially the high-tension ones. I have outlined project plans for DIYing low-cost high-tension tensegrity models similar to Hamilton’s (more detailed notes here).

-- Phil Earnhardt 10/3/11


Phil has kindly provided a list of extended resources for those interested in learning more about tensegrity:

Synergetics: Explorations in the Geometry of Thinking
Buckminster Fuller
1982, 876 pages
$12-$15 used
Available from Amazon
Free downloads of Synergetics chapters in PDF format

Kenneth Snelson: Forces Made Visible
2009, 193 pages
Available from Amazon

A Fuller Explanation
Amy Edmondson
2009, 368 pages
Available from Amazon

The entire contents of A Fuller Explanation are freely available for search and reading on Google Books. Edmondson provides a lucid translation of Fuller's work, and represents a great introduction to tensegrity.

The Tensegrity Wiki
An excellent reference for all things tensegrity: building materials, published science papers, photos of models, etc.

Bre Pettis shows how to make rubber-band tensegrity models

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