Wood expansion with gluing

[sorethumb]

Scenario;  I edge glue 2- 1 X 8 X 5' boards using biscuits.  I then would like to glue a 1 X 2 across the ends of these 2 boards. Because of wood expanding differently between length and width would this possible wood expansion present a problem, maybe causing an unwanted crack?
Laurence

[Rob Young]

Scenario;  I edge glue 2- 1 X 8 X 5' boards using biscuits.  I then would like to glue a 1 X 2 across the ends of these 2 boards. Because of wood expanding differently between length and width would this possible wood expansion present a problem, maybe causing an unwanted crack?
Laurence

Like a breadboard?  Yes, gluing all along the end of a cross-grain joint is a bad idea.

[Gary G™]

Your solution is to use the methods one used for a breadboard end.

[Bill Wilson]

There are ways to put a board across the end of a panel, as you describe, but wood movement should play a role in determining what method to use.

[Steve N]

Breadboard ends are the most common fix to your problem if the project is something like a table. Note that even if done absolutely correctly that the breadboard ends will/may/usually do look a little off for a part of each year depending on Rh (Relative Humidity) either in your home, or the greater effect of the outdoors if you allow the outdoors to come inside (open an occasional window). Why, you ask does this atrocity occur? You make the breadboard end to fit the size of the table when you make it, but through the year you know the entire top will widen, and shrink with seasonal changes. As the top move the breadboard end does not extend, and shrink, but it remains as long as it starts because movement of wood isn't with the grain, it's across it. So sometimes it's a smidge short, sometimes it sticks out a little. You can limit it by half knowing the seasonal changes where the piece will end up, by making it precise at the height or low point of seasonal change, this way it usually is off just once a year, but it can be a greater noted amount. But for centuries that has been the fix.

However on smaller pieces, and sometimes on big pieces woodworkers use dowels, drilled into wallowed out oversize holes, and darned if there isn't this new toy called a Domino, which whittles out a rounded rectangular hole you put an undersized wood chip into, and viola movement is negated. The hint of all of these methods is to NOT attach the attachment point (end of the table top) SOLIDLY to the end piece (breadboard). So you don't make a breadboard and glue it tight across the end, you pin it in place. The dowel, or Domino chip can be glued as long as there is still unglued area so the top boards can shift. Or they can also be pinned with wood points, or do a Norm Abram's from underneath with a pin/brad/nail, just don't blow through the top


The easiest way out of this is to just make the table top, and either a router, or shaper to make a design over the edges, including the end of the table. That way you just need to know a finish trick to keep end grain from coloring darker than face, and side grain so the color looks consistent.





Edit to add I reread your question, and using a piece as wide (12" end), as the top (10" top) is, is generally not going to work well. Usually the breadboard won't be much over 6" in width on a massive table, usually more like 4" wide. The fix in your case is to make the top board longer. Using a 12" wide piece for a breadboard you will need to have the perfect piece of Quarter Sawn stock. Using a flat sawn piece of wood you will almost certainly have curl, or cupping of the board so it will not continue to be straight out, but will likely curl downward, unless you use some sort of hard strut to stabilize the board. Plus you will also start to have the same problem with the breadboard as you initially thought about with the top itself, MOVEMENT. Even QS stock will move, maybe not as much, but it will move.

[DogwoodTales]

As others mentioned it's probably a bad idea, but ...
If it's only 16 inches wide and the boards are true quarter sawn, depending on the species, it might not have enough expansion to effect the glue joint.
But I wouldn't chance it.
The other issue is gluing long grain to end grain.
That's also usually not a good glue joint by itself.

[sfchuck]

Laurence, I would approach it this way:  I would make a tongue across the ends of the field boards (the two 5' long boards edge glued) and a groove in the two end boards.  The thickness of the tongues and grooves should be about 1/3 of the thickness of the boards.  Then I would glue the center 2-3 inches of each end board to the field and drill three peg holes through both the end boards and the tongues of the field where they overlap, one in the center and one 3-4 inches from each side.  Slightly elongate the peg holes nearest the ends of the tongues IN THE FIELD BOARDS ONLY to allow for some seasonal movement, then drive the pegs.  These can be glued top and bottom but be careful not to glue the elongated holes.  As has been stated, seasonal movement may cause the ends to not exactly match the dimensions of the field for some parts of the year.

[plharrison]

Breadboard ends are the most common fix to your problem if the project is something like a table. Note that even if done absolutely correctly that the breadboard ends will/may/usually do look a little off for a part of each year depending on Rh (Relative Humidity) either in your home, or the greater effect of the outdoors if you allow the outdoors to come inside (open an occasional window). Why, you ask does this atrocity occur? You make the breadboard end to fit the size of the table when you make it, but through the year you know the entire top will widen, and shrink with seasonal changes. As the top move the breadboard end does not extend, and shrink, but it remains as long as it starts because movement of wood isn't with the grain, it's across it. So sometimes it's a smidge short, sometimes it sticks out a little. You can limit it by half knowing the seasonal changes where the piece will end up, by making it precise at the height or low point of seasonal change, this way it usually is off just once a year, but it can be a greater noted amount. But for centuries that has been the fix.

However on smaller pieces, and sometimes on big pieces woodworkers use dowels, drilled into wallowed out oversize holes, and darned if there isn't this new toy called a Domino, which whittles out a rounded rectangular hole you put an undersized wood chip into, and viola movement is negated. The hint of all of these methods is to NOT attach the attachment point (end of the table top) SOLIDLY to the end piece (breadboard). So you don't make a breadboard and glue it tight across the end, you pin it in place. The dowel, or Domino chip can be glued as long as there is still unglued area so the top boards can shift. Or they can also be pinned with wood points, or do a Norm Abram's from underneath with a pin/brad/nail, just don't blow through the top


The easiest way out of this is to just make the table top, and either a router, or shaper to make a design over the edges, including the end of the table. That way you just need to know a finish trick to keep end grain from coloring darker than face, and side grain so the color looks consistent.





Edit to add I reread your question, and using a piece as wide (12" end), as the top (10" top) is, is generally not going to work well. Usually the breadboard won't be much over 6" in width on a massive table, usually more like 4" wide.  The fix in your case is to make the top board longer. Using a 12" wide piece for a breadboard you will need to have the perfect piece of Quarter Sawn stock. Using a flat sawn piece of wood you will almost certainly have curl, or cupping of the board so it will not continue to be straight out, but will likely curl downward, unless you use some sort of hard strut to stabilize the board. Plus you will also start to have the same problem with the breadboard as you initially thought about with the top itself, MOVEMENT. Even QS stock will move, maybe not as much, but it will move.

[plharrison]

Good example below. This was a bit more that I'd hoped for, but at least nothing else ever cracked. This was actually the first real project I ever made over 20 years ago.