Breadboards on a dining room table made with quarter-sawn oak

[Matt Smithmier]

I just built my first dining room table with some quarter-sawn oak, and I already have my table top glued up: 4 planks about 10" wide and two breadboards about 8" wide. The completed top is about 70" long and 40" wide and about 1-5/8" thick. After doing some research, I fear I may have been a little fast with the glue-up, and I fear I will need to chop off the breadboards and reattach them to allow for expansion. (I'm hoping I can find someone who will lend me a Domino cutter so I can use that method.)

However, I also read that quarter-sawn wood will not expand and contract nearly as much as flat-sawn, so I guess I just want to confirm with people who know more than me that I do indeed need to cut up my hard work and redo those ends. I think I know the answer, but I'd hate to do it if I don't have to.

Thanks in advance for your advice!

[Lee Schierer]

Typically quarter sawed white oak lumber will change about .0018" per inch seasonally So for your 40" you can expect about 5/64" of movement. This may of may not create a problem for your table. Generally you would want to allow the table field to move without too much restriction. This is done with either pinned or a sliding dovetail joint with just a bit of glue near the center of the span. Here is a decent reference for determining wood movement (http://www.finewoodworking.com/2013/08/29/calculating-for-wood-movement).

[Ken Grant]

here you go: http://www.woodbin.com/calcs/shrinkulator/

[Rick Fisher]

I finished a Quartersawn white oak dining room table about 4 months ago. It has breadboard ends, I fit the joint tight and put a single pin in the center underside.. No glue .. one wooden dowel .. I drilled a hole underneath and popped a dowel in .. flush cut and sanded it smooth.

I'm pretty sure my table would have cracked had I glued the whole joint .

http://i1248.photobucket.com/albums/hh499/rickfishercbs/Breadboad%20end_zps6qrvf0vg.jpg (http://s1248.photobucket.com/user/rickfishercbs/media/Breadboad%20end_zps6qrvf0vg.jpg.html)

[John TenEyck]

Cut them off and do them the right way. WO has high expansion/contraction; that's why it's mostly used as QS stock. My friend made a mahogany table last Summer, a wood with low seasonal movement. The finish cracked over the Winter at the joint where the breadboard ends meet the 40" wide table top. The breadboard joint was fine because he constructed it the right way - as you should.

Lee, with all due respect, I think your numbers are off. WO has a radial shrinkage of 5.6% according to Hoadley. That's 0.0056"/inch, not 0.0018". Over a 40" table top, that's 1/4". No breadboard end will stay stuck to the the field with that much movement if it's glued.

ohn

[Bill Dufour]

I do not think a single pin in the middle is enough. I like the Greene & Greene method with a single screw in the middle and one or more towards the ends with slotted and plugged screws holes. Putting the screws in parallel to the top surface also makes it easier to use bigger hardware with little chance of breakout.
Bill.
PS use truss head or pan head screws not flat head. I suppose pocket screws would work fine.

[Rick Fisher]

Bill.. you might well be right . The table is 40 feet from the shop .. I may have to address it ..

[Brian Holcombe]

I agree with John, cut them off ASAP!

[Lee Schierer]

Lee, with all due respect, I think your numbers are off. WO has a radial shrinkage of 5.6% according to Hoadley. That's 0.0056"/inch, not 0.0018". Over a 40" table top, that's 1/4". No breadboard end will stay stuck to the the field with that much movement if it's glued.

ohn

I went by the reference from Fine Woodworking (http://www.finewoodworking.com/2013/08/29/calculating-for-wood-movement) for QS white Oak.

[Danny Hamsley]

The 5.6% radial shrinkage is from green, and does not represent seasonal movement in a completed furniture piece.

[Brian Holcombe]

It doesn't take much movement to cause an issue.

[John TenEyck]

Wow, I was clearly mentally compromised when I wrote that first response. WO does have 5.6% shrinkage for QS lumber, but as Danny pointed out that's from green to dry. And you are correct, Lee, for the number you referenced in the FWW article. However, you have to follow through and use that value in the equation cited in the example just above it, just like I should have plugged the 5.6% shrinkage into the one presented by Hoadley in his book.

If you do that you using the formula in that linked article you get 0.0018 x 10 x 40 = 0.72" of movement for a 40" wide tabletop if the EMC changes from 6 to 16%. If you use Hoadley's method you will get the same result. Anyway, that's a pretty extreme case, but you'd still have almost 0.30" of movement for a EMC change of 8 - 12% which would be pretty typical for many areas, and not very conservative. And that's way too much movement for a glued on, or otherwise restrained, breadboard to survive. You have to let it float, just like the guys who solved this problem hundreds of years ago showed us.

John

[Frederick Skelly]

Sorry Matt, but you should bite the bullet and correct this now. You'll be far better off in the long run. For example, if you leave it as-is thinking "well, I'll just fix it when it breaks" you may have a bigger mess to clean up than the rework you've got to do now. That's because it will break at the weakest point - not necessarily cleanly and along the joint line. So you may have damage to the "main" top as well as the breadboard.

Fred

[Lee Schierer]

John, I did miss the ambient moisture change when I did the calculation. Without knowing where the OP is located, applying any firm numbers would be a guess at best, that is why we suggest everyone put a geographic location in their Bio.

I made a maple dresser set for my son and his wife with breadboard ends. The pieces were made in Northwest PA. They moved to Tucson AZ and stayed there for several years. When they returned to Central NY the field of the bread board tops had shrunk almost 1/2" in width. Within a year of coming back east, the shrinkage had disappeared.

[John TenEyck]

Lee, your example is a perfect illustration of why breadboards need to be attached so the field can expand and contract with the seasons. Since we rarely know where a piece of furniture may actually end up it's best to plan for extremes, as the FWW article illustrated. Clearly, you did, too.

John

[Matt Smithmier]

Thanks to everyone for the advice. I took it and cut off the breadboards yesterday, and plan to use the loose tenon method of attaching them with dowels. It's a good thing in the long run because now I won't constantly be worrying about the weather or the movement!

[Dan T Jones]

Somewhat off topic but how do you usually cut the tenon across the table top? Router? How to support it?
Dan