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I am in the process of building two identical patio tables with white oak. My question is how strong is gluing grain that is 90 degrees to each other, face grain? Is it a lot stronger if the two grains are parallel? Or is gluing cross grain just as strong as its all face grain? (Kind of an embarrassing question from someone who has been doing woodworking for years - I know I should know.) Tx. Randy
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Not as strong as long grain,if it were my table build I would add some stainless steel screws with glue.
White oak will turn black with regular steel and glue would help keep water out.
long grain to long grain regardless of orientation is a strong glue joint.
A crossgrain glue joint like you're showing is quite strong, within a couple of limits. First, if the glue patch is big, hygroscopic expansion and contraction may rip the joint apart. But you have a 3-4" patch, so you should be okay. Second, if you're making an outdoor table, you must use a glue that isn't weakened by water. That is, no standard Titebond/Elmers. I'd use epoxy or urea-formaldehyde.
Jamie is right. Cheers
Naw I disagree the joint will fail after a year.
Never should we rely on glue on outdoor construction.
Mother nature will win every time
I wouldn't just rely on using Titebond 3 for these 4 joints. I would put a screw in each and every one of them for good measure. What is going on in the center where the four members connect? Is that a half lap joint? I'm thinking that is another possible problem spot. If it is a half lap (bridle joint) then that's great.
Definitely use mechanical fasteners.
The end joint in the pic is with Titebond 3 and will have two screws in each 4" patch. The halflap joint in the middle (with an added spacer for added strength) is with epoxy (West Systems 601). Most of the construction is with epoxy with some non stressed joints and "spacers" held together with Titebond 3. The base and uprights are glued together with epoxy and are all mortise and tenon construction. I used my new-to-me Jet mortising machine and was quite impressed as I cut through 2" of white oak for hours without any issues. I'm guessing the 1/2" mortising bit was new as I could see no use or discoloration on it, so that sure helped. I held my shop vac sucking up waste out of the mortising bit as it cut, and I'm sure that helped cool it also with all that air rushing by it. As an aside, I built a similar table 20 years ago with redwood using Titebond 2 and it lasted a good 15 years outside (I live in moderate central Calif) before showing any signs of delaminating at the glue joint. I repaired it by putting in screws about 5 years ago. The redwood is really cracking, hence my replacing it with a new table (and making a second one at the same time for my daughter). As I'm 70+, this one of white oak should last me till I croak.... Thanks for all the good advice. Randy
If you are using screws and it's outdoor furniture, make sure they are stainless steel. Second, it might not be a bad idea to use a slotted hole to permit the cross-grain wood to move a little under the head as the wood expands and contracts. The secured wood isn't that wide so it might not be a problem, but since wood moves as moisture and temperature change, I'd be a little concerned that wood secured without the slot would split over time. Could be wrong though as I always tend to be extra careful and overtaking and overbuild.