Turning Archive 2005

Subject:
Segmented bottoms cracking, Why? *PIC*

Greg in Oshkosh
>My friend John Bartlet does quite a bit of segmented turning. He almost always segments the bottom of the bowls he turns too. Recently he put bowls in a shop. 5 of 18 had the bottoms crack. Note that this was in Wisconsin in the winter, where the humidity indoors is drier than Arizona. The bottoms segments are cut with the grain running across the segment, so the bottom should expand radially. They all crack across the center of the bottom with the bottom edges still looking good. He uses titebond glue. (not titebond II) I think that the wood shrinks radially and since the out sides are glued to the bowl sides the wood shrinks away from the center. With endgrain glueing the crack follows the glueline. Is this anywhere close to correct?? Can you suggest a way to prevent it from happening?? TIA

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