Does Grain Direction Matter in a Segmented Bowl

[Jon Shull]

I am just getting started with segmented bowl turning. I made a wedgie-sled that seems to be pretty accurate, and I want to experiment with adding varying sizes of strips between wedges to make the rings larger as I move from the base of the bowl. I have a bunch of long thin strips of walnut that I want to alternate with some maple. Will I be able to alternate the side-grain wedge of maple with an end-grain strip of walnut, or will I get too much tear out of the walnut? I would appreciate your advice on using the strips. Thanks.

 

[Gabriel Hoff]

If you cross cut the walnut instead of ripping it you should end up with the grain running the same way. Ripping exposes the side grain but if you cut the piece and use the ends of the strips only it will be end grain. Cross cutting should fix it as the piece will be side grain when using the edges. I don't think it will effect tear out unless your tools are dull. Sharpen, take light passes, keep the speed high are all good ways to reduce tear out. If I'm wrong here feel free to suggest or correct!

 

[Jerry Bennett]

Jon, you can easily cut the inserts with the wedgie sled. Cut from one fence as thin as you want. It is demonstrated in the Segmentology videos. Works great and the grain will be running in the right direction.
Jerry

 

[Rusty Nesmith]

If you rip the board you will be gluing end grain in your rings. I prefer this way because that will eliminate end grain in the turning.

 

[john lucas]

I'm not the expert than Jerry is or for that matter many other segmented turners. I have made a lot of glued up pieces over the last 45 years. It's all about wood movement and appearance. End grain looks different that side grain after you put finish on. That should be a major consideration. Wood movement is a very major consideration if you want the piece to last for more than a few years. What I've found is a lot of very small pieces of wood are used as decoration on segmented rings or in my case my mirror designs. The amount of wood movement in these pieces is extremely small. You can look up in charts to see how each species moves in the 3 directions wood moves. I've found that there isn't enough wood movement to cause problems if the pieces are thin. Most of the problems come from gluing up pieces that are 3/4" or larger with the grain not matching. Or even worse adding solid wood to the tops of segmented vessels. there have been many good tips on gluing up solid wood bases into segmented turnings. I cheat. I resaw the base into 3 or more pieces and rotate them as I glue it back together making it more or less a piece of plywood.
How you glue the wood is just as important. End grain to end grain is the weakest. end grain to side grain just a little better. Side grain to side gain is stronger than the wood. So if you rip a 1/8" piece and plan to put that as decoration between 2 side gain pieces in a segmented ring you potentially have a weak point due to wood movement but it's a little stronger than plain end grain to end grain. What I have seen fairly often is people cutting bowls or platters of solid wood and inserting the thin long grain slices without paying attention to grain direction. These will fail sooner or later because the large pieces have a lot of movement compared to the thin strips. On a segmented ring it's not as critical because each segment may only be an inch or less in length and height.
I made this piece after doing more research on wood movement and glues. I thought it would be fun to show a mirror with the inlay's coming unglued over the years. This was my interpretation of that failure.

 

[Jon Shull]

If you cross cut the walnut instead of ripping it you should end up with the grain running the same way. Ripping exposes the side grain but if you cut the piece and use the ends of the strips only it will be end grain. Cross cutting should fix it as the piece will be side grain when using the edges. I don't think it will effect tear out unless your tools are dull. Sharpen, take light passes, keep the speed high are all good ways to reduce tear out. If I'm wrong here feel free to suggest or correct!

If you rip the board you will be gluing end grain in your rings. I prefer this way because that will eliminate end grain in the turning.

I'm not the expert than Jerry is or for that matter many other segmented turners. I have made a lot of glued up pieces over the last 45 years. It's all about wood movement and appearance. End grain looks different that side grain after you put finish on. That should be a major consideration. Wood movement is a very major consideration if you want the piece to last for more than a few years. What I've found is a lot of very small pieces of wood are used as decoration on segmented rings or in my case my mirror designs. The amount of wood movement in these pieces is extremely small. You can look up in charts to see how each species moves in the 3 directions wood moves. I've found that there isn't enough wood movement to cause problems if the pieces are thin. Most of the problems come from gluing up pieces that are 3/4" or larger with the grain not matching. Or even worse adding solid wood to the tops of segmented vessels. there have been many good tips on gluing up solid wood bases into segmented turnings. I cheat. I resaw the base into 3 or more pieces and rotate them as I glue it back together making it more or less a piece of plywood.
How you glue the wood is just as important. End grain to end grain is the weakest. end grain to side grain just a little better. Side grain to side gain is stronger than the wood. So if you rip a 1/8" piece and plan to put that as decoration between 2 side gain pieces in a segmented ring you potentially have a weak point due to wood movement but it's a little stronger than plain end grain to end grain. What I have seen fairly often is people cutting bowls or platters of solid wood and inserting the thin long grain slices without paying attention to grain direction. These will fail sooner or later because the large pieces have a lot of movement compared to the thin strips. On a segmented ring it's not as critical because each segment may only be an inch or less in length and height.
I made this piece after doing more research on wood movement and glues. I thought it would be fun to show a mirror with the inlay's coming unglued over the years. This was my interpretation of that failure.

Jon, you can easily cut the inserts with the wedgie sled. Cut from one fence as thin as you want. It is demonstrated in the Segmentology videos. Works great and the grain will be running in the right direction.
Jerry

Thanks to all of you for your insights. As a newbie, there are lots of things you don't know that you don't know. For example, I hadn't thought about the use of solid wood on top of a segmented vessel. Is it a problem to use solid wood on the bottom of the bowl as well? I guess I'll try the resaw/plywood method John suggests for the bottom as well. Thanks, again.

 

[Brian Gustin]

Is it a problem to use solid wood on the bottom of the bowl as well?

Not at all. In fact I suspect it may be a recommendation of most. After all you need something to build your foot and/or tenon/mortise for work holding, and segmented pieces under the stress of a mortise would be liable to come apart quite quickly, I'd think.

 

[Jon Shull]

Not at all. In fact I suspect it may be a recommendation of most. After all you need something to build your foot and/or tenon/mortise for work holding, and segmented pieces under the stress of a mortise would be liable to come apart quite quickly, I'd think.

Thank you.