Replies

1. 
   JohnWW | Feb 09, 2008 11:01pm | #1

   You are confusing simple linear expansion, which the slots in the frame and panel assembly will allow room for, and twisting and curling. A well made panel will stay more or less flat it will only get wider or narrower with changes in humidity.

   Wood with wild grain and stress in it, like the crotch wood you have, will quite possibly turn into a potato chip shape as it gains or loses moisture. The joints in the frame may, or may not, be able to resist the stresses created as the wood curls up.

   John White

   
   

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   Edited 2/9/2008 3:03 pm ET by JohnWW

1. 
   bmarples | Feb 10, 2008 12:03am | #2

   Thank you for your answer. Would I be better advised to thickness sand the solid feather crotch walnut to 1/2 " and glue it to a stable substrate such as Baltic Birch plywood and then frame that ?

   Dave.

1. 
   JohnWW | Feb 11, 2008 01:26am | #3

   The best approach is to resaw it to under 1/8" thick and then glue it onto a base like birch plywood. A 1/2" thick slice will probably self destruct glued to an immovable substrate. You need to get the outer layer thin enough that it will not be able to overpower the glue and the base material, and that means it has to be thin.John White

1. 
   bmarples | Feb 11, 2008 04:23am | #4

   In February 2002 Fine Woodworking issue No. 154, Lonnie Bird built a secretary desk using 5/8" thick solid crotch cherry panels and a small center prospect door made from solid crotch cherry which were framed with straight grain cherry. I don't understand why he used this design if everyone says crotch grain is so structurally unstable. He even used a solid piece of crotch cherry for the lid.  Please help me understand the conflicting logic.

1. 
   JohnWW | Feb 11, 2008 06:53pm | #5

   It can be done but it is risky. Some figured boards can twist very badly as they gain and lose moisture. Lonnie did say he lets the stock acclimate to the shop before using it. I would guess that he gives the wood enough time, most likely over the course of a full year, to see how the stock will react to all types of weather, and he culls out the planks that are the least stable. He also mentions using full size mortise and tenon joints for the frame to make the frame as strong as possible. I would be willing to bet that at least some of his doors, and desk tops, made this way, aren't quite flat occasionally. I have certainly seen a number of similar pieces, not made by Lonnie, that have had problems.I'm more cautious than Mr. Bird, I would use veneer for the same application although this wouldn't allow raising the panels. If you want to try it, there isn't any great risk involved, at most you would have to live with a warped door or have to rebuild the door at some point in the future. If you are lucky, and choose your wood well, the door will stay flat, but it is a gamble.John White

   Edited 2/11/2008 11:00 am ET by JohnWW

2. 
   bmarples | Feb 12, 2008 02:25am | #6

   Thanks for your reply. Very informative. It's heartening to receive a reply from someone who knows the subject well. Your reply will factor heavily my future fine woodworking.

   Dave.

3. 
   JohnWW | Feb 12, 2008 02:33am | #7

   Don't take me too seriously, take risks occasionally and have some fun.John W.

2. 
   bmarples | Feb 16, 2008 08:32pm | #8

   Hi again ! I came across a piece of solid crotch walnut and solid burl walnut that, during my infancy of wood knowledge, I had framed with birdseye maple using a tongue and dado technique. They were both framed about 5 years ago. I notice some tiny hairline cracks in the crotch that were not there before but I see nothing in the burl. I suppose the cracks are a sign of the unstability fine woodworkers talk about. Do you know what the future holds ? Will these cracks multiply or get deeper ? Will the panel eventually crumble apart ? If all that is going to happen is a few hairline cracks will appear, this in and of itself is not too troubling from an aesthetic view, it is still beautiful. Can you tell me what will eventually happen ? Also, why does the burl show no hairline cracks ? It's grain goes every which way too ?

   Thanks,

   Dave.

1. 
   JohnWW | Feb 20, 2008 02:06am | #9

   Cracking is primarily caused by localized unequal shrinkage of the swirling grain in the highly figured wood. Cracking is pretty much self limiting, the cracks will even close up in prolonged damp weather only to open up again during dry spells. The cracks will only get larger if the wood is exposed to conditions that are even dryer than anything previous, which is always a possibility. It is very unlikely that the cracks, since they are small now, will ever cause the panel to fail. The grain in the burl is so interlocked that the piece reacts to moisture like plywood, the thin layers crossing each other create a stable, though stressed, assembly. The risk with highly figured wood used as a panel, isn't that the panel will crack, which is usually just an appearance problem, but rather that it will warp and create structural problems for the piece of furniture the panel is mounted in. Not all figured wood will warp so it is sometimes worth taking a chance using it, but it is hard to know in advance how the wood will react to moisture swings unless you can watch it over the course of a year in an environment with large moisture changes. John W.