Sproing!! Stretching spiral-cut culms

[Mark Meckes]

This spiral-cut culm of Phyllostachys viridis was part of an experiment made around 5 years ago, using a bandsaw to cut the spiral.
Recently, while crouching over a portable electric space heater the other night to keep warm, I thought of putting this now aged spiral, currently in use as a pen/pencil holder, next to the heater, warming it up, then putting bamboo spacers between the coiling, to see if it is still elastic enough to be stretched...
Photos:
Stretching with heat and spacers
http://www.bamboocraft.net/gallery/data/522/thumbs/1BSproing-824.JPG See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=137)

After first heating the spiral till it was hot to the touch, I inserted bamboo spacers in between the coils, starting off using shorter spacers, gradually increasing their size.
I was impressed at how pliable the bamboo continues to be. It could have been stretched even more.

Spacers removed, after cooling
http://www.bamboocraft.net/gallery/data/531/thumbs/1MVC-827F.JPG See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=129) http://www.bamboocraft.net/gallery/data/531/thumbs/1BSproing-828.JPG Inside spiral (http://www.bamboocraft.net/gallery/showphoto.php?photo=138) http://www.bamboocraft.net/gallery/data/531/thumbs/1BSproing-830.JPG Close up (http://www.bamboocraft.net/gallery/showphoto.php?photo=139)

Jumping Jack - needs a box
http://www.bamboocraft.net/gallery/data/533/thumbs/1BSproing-831.JPG See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=140)

~ Mark

[Mark Meckes]

How sproingy is it?
http://www.bamboocraft.net/gallery/data/533/thumbs/1SproingTest-021.030130.JPG See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=152)

This coil is stiff like a bed-spring.

http://www.bamboocraft.net/gallery/data/533/thumbs/1SproingTest-026.030207.JPG
See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=153)

Yup, this coil has a medium-heavy duty, shock-absorber type sproing. Not a slinky . It required 2 1/2 lbs to compress the spring.

http://www.bamboocraft.net/gallery/data/527/thumbs/1SproingTest-043.030207.JPG See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=154)

This spring coil has a musical rhythmatic vibrato sproing to it when it is pulled apart and released, or when it is held horizontally with one hand and wiggled up and down.
Yep...that's 'Sunshine' the marionette doing a jig!

Stretch-Uncoil - inside
http://www.bamboocraft.net/gallery/data/531/thumbs/1SpringCoil-031.030207.JPG See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=155)

This spring coil was heated, stretched and uncoiled.

Stretch-Uncoil - Outer view -unfinished
http://www.bamboocraft.net/gallery/data/531/thumbs/1SpringCoil-042.030207.JPG See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=156)