Replies

1. 
   Bob_Van_Dyke | Nov 12, 2007 12:39am | #1

   A couple of things come to mind-
   1. I always flatten and plane my parts before I glue up- and then flatten (if possible) and plane to finial thickness- the panel will be more stable that way.
   2. more importantly- and I suspect this is the problem- does each glue edge have straight grain on the face or is it wavy (or "points")? If it is straight then you are glueing the rift sawn part of the board to the rift sawn part- which is good- that joint will be more stable and will yield a flatter panel (and the glue line will be hidden in the straight grain). If on the other hand you do not have straight grain on the glue edge then you are probably glueing up an edge that is from the flat sawn part of the board which will not be nearly as stable.
   Looking at the end grain you should see growth rings at 45 degrees to the face (rift sawn). If they are parallel to the face you are using the flat sawn section of the board and you will have a glue up which will probably cup.
   Hope that is clear
   Bob Van Dyke

1. 
   SKme | Nov 13, 2007 12:13am | #2

   Bob,

   Many thanks for your advice.  Having analysed a couple of pieces the end grain growth rings are at 45 degrees.  The process I follow for producing a top/flat board is as you suggest.  The finshed piece is falt, but over a number of months the tops slightly cup by about 1-2mm.  Would you think it is anything to do with the moisture content in the wood and a centrally heated house?

   Regards

   Scott

1. 
   Bob_Van_Dyke | Nov 14, 2007 06:59pm | #3

   it could be moisture or heat - the other thing that can make a difference is how the board is oriented with regard to cupping-
   If I can orient the board so that the face which is the "inside of the tree" is up then if the board does cup it should cup down- (towards the "outside of the tree") and you will not notice the cupping as readily.
   Bob Van Dyke