turning a crescent

[Brujo]

Greetings all,

Can any body give me some advise on turning a crescent? I saw a piece on the WOW website that is two crescents held together by thread. I'm curious as to how the crescents where created.

Thanks

 

[Joe Greiner]

Can you post a picture of the work in question? Probably a lot of non-WOW members here. Copy the picture, "Save As" with your own filename, and select "Manage Attachments" for submittal.

Joe

 

[Wipedout]

I believe this is the one he was talking about - it was posted on woodnet as well. Created by Jacques Portal - beautiful works

More views are here http://www.la-truciolara.com/forum/Portal005.htm click to change views3

more info on the woodnet post here: http://www.forums.woodnet.net/ubbth...&Number=3690590&page=1&view=collapsed&sb=5&o=

 

[Ed_McDonnell]

Looks like a disk with a hole turned off center and then carved to round off pointy edges.

I can't imagine how long it took to set the "rigging" on that piece. I can imagine the dust bunnies that something like that would attract around my house.

Ed

 

[Brujo]

Thats the one.

I'm wondering if the lines that divide the crescent are carved or if that was done on the lathe?

 

[Brian Hahn]

If I were doing it, I would turn the lines on the crescent. That means turning the crescent using 5 different center points - 1 for the outside edge, 3 for the lines and 1 for the inside hole.

 

[Joe Greiner]

The crescents themselves were most likely turned with the piece mounted eccentrically to cut the inside, and carved to create the gap between the cusps.

Two other questions are at work here:
1. How did Jacques build it?
2. How would YOU build it?

Claude posted this on a few other forums, where he said the surface was achieved by wire brushing. Other than that, question no. 1 should be directed to Jacques, perhaps via Claude. (Claude is a member here, too.)

For question no. 2, speculation can run wild. But here's my take on it:
Rigging of constructions like this is best done with use of disposable temporary supports, arranged so as not to interfere with threading the strings. For the attached whimsy (made many many years ago), I attached the straws to the faces of a cardboard cube with interlocking edges. After threading the strings, I just cut away the cardboard. I note that Jacques has an unidentified insert on the rims of the pieces. I think my temporary supports would be sheets of heavy cardboard or Masonite engaging the slots for the later inserts. The sheets would extend to a surrounding box to hold the two pieces in position. The box would have access holes to facilitate threading. Even with that, though, tensioning the strings could be an adventure: the six strings on a guitar need to be re-tuned as each string is tensioned; on this piece it would be even worse.

Claude probably used some props to support the piece for photography, and edited them out of the picture files. At least that's how I'd do it.

Joe

 

[Don O. Jr.]

Rigging

There is a photo posted I believe on WoW that shows a rigid support holding the 2 crescents together for placing the lines. It is then removed when the lines are completed.

I can't imagine how his brain works to come up with this idea and actually pull it off ! It's a really wonderful piece. The turning was probably the easy part.

 

[Claude]

http://www.la-truciolara.com/forum/Portal010.htm


and that is the way how he describes the weaving:

"I start by keep together crescents in their final position. The immobilization piece should be removed easily once the weaving done. It is a square section wooden piece whose length is the distance between the 2 crescents, its section is equal to the thickness of crescents. 2 other wooden pieces immobilized on 2 opposite sides by serflex extend square section piece on both sides to come close crescents. (for more visibility I replaced serflex by beautiful strings!).
For weaving, there are 2 strings networks : those who are tense between the 2 crescents extremities and tend to move away one from other. And those who are tense between the parties broader 2 crescents and tend to bring them closer. The balance of tensions that ... it takes! Finally ... Yes, whew! It's nice when a theory is true, but there is always a small pinch at the heart of removing the scaffolding ...
I use 2 spools to go alternately, the string of each networks.
I start with the network that tends to bring the crescents closer, 2 round trips or 4 strings. Then the other network : 4 strings. Then ... and so on. In trying to keep a constant tension.
I end as I began, by a node.
I remove immobilization piece ... holding my breath ...

 

[Joe Greiner]

Thanks, Claude. You're a prince.

I hadn't noticed the gaps that Jacques exploited. His method is a lot more effective than my speculation, and allowed better construction of the insert rim.

Joe