Thread: Shrinkage

YOur problem is a classic cross grain situation. You have to make sure that when putting all pieces of wood together you always see the edge and not the end grain. YOur expansion and contraction will always happen even after you apply a finish to it. I am surprised it hasn't cracked on you yet.


Mark

I'm curious as how the fact that the endgrain is hidden makes it more succeptable to movement? I assumed same wood, same thickness, same location should move in the same way regardless of orientation within the piece?

How does this effect parketry (sp?) floors?

I am assuming Save that your question is directed at me. I will also assume that you are testing my knowledge of wood movement.

If you hold up a board and have the grain running north to south, that piece will expand east to west. In essence it will never get longer but it will get wider and thicker. I have been shown mathemactical equations as long as your arm to determine how much a piece will move but that can be left for another discussion and personnally i don't use them I just account for the fact that wood moves. The wider the piece of wood the more it will move. I know this is an over simplified explanation but it is true.

If I understand what Jon did, and I may have it wrong, the grain on his side pieces go front to back which means that the wood will move top to bottom or the table will get taller or shorter through the years. The grain for his top runs side to side so the movement goes back to front. this is opposite to his sides which is why he notices his top getting wider or shorter. Thsi is not good. Jon should have orientated his grain to run the same way on all three pieces so that he would not notice any wood movement. If you laminate 3 pieces of wood together adn glue them up they in fact with respect to wood movement become one piece. I will attach a picture of a table top I made recently. It has curly maple, walnut and cherry mixed together. it took me a long time to plan out how to assemble this table top. One of the first things I did was when i ripped the pieces into three inch widths I marked which way the grain went so that all 101 pieces of wood had the same grain orientation.

As far as Parquet Floors as concern the pieces as small enough that wood movement is not noticeable but it is still there. this is where those mathemactical formulas come in handy.

I hope I passed the test.

Mark

Mark,

first , top table
Second, not a test I was complete bamboozled. I actually had the wrong end of the stick, I thought the centre piece was getting thicker/thiner at a faster than the surrounding pieces, rather than wider and thinner in a different direction. . Shows I'm drawing on many years of rigorous inexperiance.
Excellent answer thanks

Hey, fellow Canuck, you certainly passed the test with that table top. Is this your own design, or did you work from plans?

How about a few more pic's on some of your other woodworking projects, they are inspirational.

Howdy Mark,

I've seen that table before, seems to me it started out with over 100 seperate pieces.

Thanks Australia for a great forum, I have enjoyed it for quite awhile now and just wanted to jump in and say hello from Newmarket Ont. Canada.

All the best
Gord

Mark,

nice table.

The reason that I did the lamination with the grains at 90degrees is to match a commercially purchased shelf unit in the same room. I understand exactly what you have said and it is what I thought.

I must admit the bought one appears to have a very thin shim of something else between the laminations that is slightly recessed from the edge. Because of this recess it is not a pefectly flush edge anyway. I will have to watch to see if my joints crack as you have warned.

thanks.