Staved segmented construction

[Mike Stafford]

Charles' Bon Bon jar brings to mind a back in the day for me. I used to do segmented staved bowls frequently. I had access to some thick stock that was 1 1/2" to nearly 3" thick. I bought this material in bundles from a specialty millwork shop. They would not use the cut offs from the large boards they used to make doors, moldings etc. They would bundle this up with pallet shrink wrap and sell the bundles for $5 each.

I would use this thick material and make compound mitered bowl blanks. People said they would not stay together glued in the manner I used to make these blanks/bowls. Almost 20 years later they are still together just fine.

Here are a couple that I made. These are old pictures so be gentle.

. This is bubinga and the board were 6/4 stock.

This is maple with a walnut foot. Made from 10/4 stock.

These were glued together with polyurethane glue.

 

[Vaughn McMillan]

Nice-looking bowls, Mike.

...These were glued together with polyurethane glue.

That right there seems to be a miracle of some sort.

 

[Chas Jones]

.....
I would use this thick material and make compound mitered bowl blanks. People said they would not stay together glued in the manner I used to make these blanks/bowls. Almost 20 years later they are still together just fine.......

They have done well to survive the years, probably because all segments are from the same species and batch of wood therefore have reacted evenly from humidity changes. End-Grain to End-Grain joints are the riskiest, I've had a few fail over the years due to the swings between UK high humidity and direct sunlight or central heating exposure when different wood species are involved.

 

[Mike Stafford]

They have done well to survive the years, probably because all segments are from the same species and batch of wood therefore have reacted evenly from humidity changes. End-Grain to End-Grain joints are the riskiest, I've had a few fail over the years due to the swings between UK high humidity and direct sunlight or central heating exposure when different wood species are involved.

Yeah, i know that end grain to end grain is a no-no. I took a segmented class from Don Russell who taught segmenting using end grain joinery mixed with side grain. None of the pieces from that class have ever failed either. I don't know why as it should be doomed. It is hard to see in the picture but there are 4 bands of veneer plywood. Each band contains three layers of veneer cross banded. I sometimes wonder if that is what holds it all together.

Here is one of the pieces from that class.

 

[Chas Jones]

Yeah, i know that end grain to end grain is a no-no. .......I don't know why as it should be doomed. ......]

As I understand it, it's all to do with small cross section areas presented by the individual end grains and the lack of glue penetration to aid the grip.

 

[Ryan Mooney]

There was one piece at the local art co-op that was more "crazy grain" (he had pieces going all directions). It looked pretty cool from across the room, but up close the pieces had had significantly different expansion/contractions. I suspect everything wasn't fully equalized moisture wise initially.. but there was a lot of different species as well some significantly harder/denser than others. So some chunks were 1/8" or more proud of others and there were a few pretty decent cracks forming.

I think I agree that one of the things that's working for the Don Russell class example above and some of Chas's work may be the inclusion of small thin pieces to absorb some of the differential. I know that works on veneer work (sold core plus two thin cross banded veneer layers on top has proven quite stable for 100's of years in some cases) so I would imagine it would also help here. The plywood inclusions probably work somewhat similarly and probably even one or two thin layers would help to some degree.

I dunno how to explain the staved bowl, the PU is pretty flexible as far as glues go and does tend to foam out into the wood some so maybe that explains it?

 

[Dave Hoskins]

Them's downright purty, Mike.