Correct way to glue up 2 thick pieces?

[Brian Penning]

I glued/laminated up 2 pieces of white oak 2" thick, 36" long and 11 inches wide. Ended up with a 4" thick piece.
Used Titebond 3.
However, 6 hours later while planing the oak down to a 3" thick piece the piece started cracking. I could actually feel and hear it crack. I've now got 1 big mutha of a crack on 1 side and several smaller ones elsewhere.
Any ideas why this happened?
I did the grain orientation as if the 2 pieces were like so ")(". Should I have done it like "((" ?
Wood moisture?
TIA for any and all replies.

[JohnT Fitzgerald]

I glued/laminated up 2 pieces of white oak 2" thick, 36" long and 11 inches wide. Ended up with a 4" thick piece.
Used Titebond 3.
However, 6 hours later while planing the oak down to a 3" thick piece the piece started cracking. I could actually feel and hear it crack. I've now got 1 big mutha of a crack on 1 side and several smaller ones elsewhere.
Any ideas why this happened?
I did the grain orientation as if the 2 pieces were like so ")(". Should I have done it like "((" ?
Wood moisture?
TIA for any and all replies.

Brian - did it crack along the sides along the glue seam? or was it on the ends? or along the faces?

Were the boards milled (i.e. planed) to with/thickness shortly before gluing? Had they been in your shop long enough to 'acclimate'?

[Brian Penning]

Brian - did it crack along the sides along the glue seam? or was it on the ends? or along the faces?

Were the boards milled (i.e. planed) to with/thickness shortly before gluing? Had they been in your shop long enough to 'acclimate'?

Along the faces.

Yes milled to thkness just before gluing.
Not long in shop at all.

[Chris Padilla]

Pictures would really help us to help you, Brian.

Grain orientation isn't necessarily the problem but I wonder about the moisture content of each board. Were they wildy different?

I also question working the wood after only 6 hours of drying time. Remember, when one glues up a board, moisture is being added via the glue. Further, moisture is often being added non-uniformly (one side...one face...etc.) and so I would always give the freshly glued piece a day or two to dry back out to its original "before-glued" state...especially if a lot of glue was used...like it was in your case face-gluing 396 square inches of wood. :)

Still, I'm not sure how or if this is related to the cracking....

[Brian Penning]

The crack actually widened overnight.
Both pieces were originally a 6' piece cut in half.
Been thinking that perhaps I should've planed the 2 pieces closer to the 1.5" before gluing them up.
Instead I had an almost 4" glued-up thick piece in which I was taking close to a ½" off each side.

[Gary Herrmann]

Was the wood wet? Or even if it was dry and had been outside for awhile, it needs to acclimated to the shop before working it. A week or two is typical. Either of the above situations could have caused cracking.

[Bob Lang]

Even though pieces will stay together after a few hours, the glue needs 24 hours to really be dry enough to work. Also the comment "not long in the shop at all" suggests that the wood was either gaining or losing moisture, therefore changing in size as you tried to work with it. As someone else said, that much glue sandwiched between two hunks of wood contains a lot of moisture, and the moisture has to go somewhere. You might have been able to get away with one of these things, but not three.

Bob Lang

[Tony Bilello]

I glued/laminated up 2 pieces of white oak 2" thick, 36" long and 11 inches wide. Ended up with a 4" thick piece.
Used Titebond 3.
However, 6 hours later while planing the oak down to a 3" thick piece the piece started cracking. I could actually feel and hear it crack. I've now got 1 big mutha of a crack on 1 side and several smaller ones elsewhere.
Any ideas why this happened?
I did the grain orientation as if the 2 pieces were like so ")(". Should I have done it like "((" ?
Wood moisture?
TIA for any and all replies.

I dont glue up pieces that thick very often but I do it several times a year. Over the years I have never had the cracking problem.
My best guess is that the wood was not dried sufficiently. Once you started to remove the outer layers, it was easier for the moisture to escape. When it was surface drying, it was shrinking and thus cracking. It could no longer shrink on the glued surface because it was now air tight.
The other possibility is that the two glue surfaces were not flat and the clamping caused internal stresses on the now "one solid piece". As you removed the outer thickness, the thinner board started to split. This scenario is not likely though because I will assume you had joined/planed the boards properly before glue up.

[Karl Card]

If you had just planed the pieces on one side the board will move also. Even tho tite bond says you can do things with the wood after it sets in 30 minutes I have alwasy let mine set over night. It seems to work better and doesnt gum up your tools and also has a stronger hold. if the wood was at least 2 inches thick also it will take it along time to try. I have 4 2 inch thick cherry pieces that are 76 x 22 x 2 and i am figureing on at least a year before they dry.

[Frank Drew]

I have 4 2 inch thick cherry pieces that are 76 x 22 x 2

Yowza! Not easy to find cherry that wide in that thickness these days. Are the boards nice? Do you have a job in mind for them yet?