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Quartersawn glue joint failure

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Forum topic by jroskey posted 01-07-2018 05:15 PM 849 views 0 times favorited 20 replies Add to Favorites Watch
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jroskey

9 posts in 2939 days


01-07-2018 05:15 PM

Hello,

I’m a woodworker in upstate new york and we do a lot of large dining tables. We have had a lot of trouble with white oak the past year – mostly flat sawn checking at the ends and on the faces (case hardening), so we have gone to 100% quarter sawn material. Recently, in our showroom I have failure at the glue joints of a 1.75” thick dining table that is located approximately four feet from a radiator. The other end of the table is fine. Glue is TB3. Would going to a flexible epoxy adhesive be a better choice for oak? Photos attached.


20 replies so far

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CaptainSkully

1601 posts in 3638 days


#1 posted 01-07-2018 05:24 PM

Ouch. A couple of questions. Are there any mechanical connections in this joint (biscuits, Dominos, etc.) or just edge-glued? Second, is there sufficient allowance for cross-grain movement allowed in the undercarriage? I’ve seen tables pull themselves apart when the top is not allowed to move. Was the wood allowed to dry sufficiently before the top was made and then put in front of the radiator? QSWO is pretty resistant to adhesives, especially when very smooth (e.g. jointed edges).

I would go for a two-part epoxy for the repair. A second alternative would be to rip the offending joint off at the table saw and reinforce with the mechanical connection of your choice. I’d be interested in seeing the psi comparison between various one and two-part adhesives. Hmmm…

That’s a beautiful piece of table top. Good luck with whatever you decide. I’m ASSuming since you have a showroom that your level of expertise is well beyond mine, I’m just bringing up some topics for conversation to try and help all of us.

-- You can't control the wind, but you can trim your sails

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Luthierman

221 posts in 1167 days


#2 posted 01-07-2018 05:32 PM

The only time I have ever had this kind of failure was when 1) The joint wasn’t actually straight and was forced into submission through clamping force or 2) the wood wasn’t dry enough or properly dried in the kiln.

Now, the radiator. I have destroyed a guitar top being too close to a heat source. Even at ten feet away the top split because of the variance of temperature of the top, which was facing the radiant heat source, and the back which was against the wall. I think one could relate this to the same situation as you. With these unbelievably cold temps, I could see the temperature differential getting pretty high on the different surfaces of the wood.

-- Jesse, West Lafayette, Indiana

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jroskey

9 posts in 2939 days


#3 posted 01-07-2018 05:33 PM

Thanks for the reply. There are no mechanical connections. We usually take boards straight from the big jointer (20” SCMI) and glue from there. We have a pretty good clamping system to keep them flat. That said, It might make sense to reinforce a QS joint with a big 10mm domino since the movement is up and down, and the glued FS edges are resistant to glue. Also, the other side of this table is perfect…it’s only the side that was nearest the radiator. We purchase all of our white oak through a very large and reputable supplier on the East Coast. That said, there can always be trapped moisture in oak.

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Loren

10477 posts in 3727 days


#4 posted 01-07-2018 05:49 PM

Sprung joints might help avoid the problem.

I have my doubts as to whether using another
glue will help.

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OSU55

1779 posts in 2069 days


#5 posted 01-07-2018 06:02 PM

^ Agree with “sprung joint”. I suspect the joint was forced together. The slight gap needs to be at the joint center. Gaps at the end result in this type of failure. From the pic it appears the some of the glue joint failed but also solid wood, so I would not consider it a glue failure. I suppose biscuits or dowels might have prevented the failure, but a properly done butt joint doesnt need them.

View bondogaposis's profile

bondogaposis

4889 posts in 2431 days


#6 posted 01-07-2018 06:04 PM

I don’t think the glue is the problem, it is the radiator. Locate your next table somewhere else and see. My guess is that the wood picks up moisture from the glue, then on the radiator side it is drying too fast, causing the wood to shrink faster on the ends than the rest of the top. Moisture will always move faster out the ends, but in this case it is too fast. I am assuming you have allowed for wood movement in the way the top is attached to the base.

-- Bondo Gaposis

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Aj2

1576 posts in 1877 days


#7 posted 01-07-2018 06:41 PM

Looks like someone’s jointer or operator is off. I think the long grain glue surface On white oak is plenty strong. Cutting it away to add a domino is just adding more water the wood has to deal with and not necessary.
When you have all your boards in your clamps try clamping one side.Do the boards open up like a fan?
I also agree with comments above

-- Aj

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jroskey

9 posts in 2939 days


#8 posted 01-07-2018 08:01 PM



Looks like someone s jointer or operator is off. I think the long grain glue surface On white oak is plenty strong. Cutting it away to add a domino is just adding more water the wood has to deal with and not necessary.
When you have all your boards in your clamps try clamping one side.Do the boards open up like a fan?
I also agree with comments above

- Aj2

I don t think the glue is the problem, it is the radiator. Locate your next table somewhere else and see. My guess is that the wood picks up moisture from the glue, then on the radiator side it is drying too fast, causing the wood to shrink faster on the ends than the rest of the top. Moisture will always move faster out the ends, but in this case it is too fast. I am assuming you have allowed for wood movement in the way the top is attached to the base.

- bondogaposis

We do about 20-30 large dining tables a year, and made two in walnut around the same time this one was made…no issues. I’m going to guess radiator at this point (though it’s never been an issue with walnut tables in this location in the past). There’s plenty of allowance for movement in the base. No when we clamp up there is no fanning of the boards…our big jointer is solid and boards are dead straight…that’s why I’m thinking a spring joint might be the way to go.

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jroskey

9 posts in 2939 days


#9 posted 01-07-2018 08:03 PM

Here’s the table in better times about a month ago.

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BobLang

156 posts in 3480 days


#10 posted 01-07-2018 08:17 PM

Do you have a moisture meter? Do you know what the humidity is in your shop or your showroom? Looks to me like the wood is wetter than it ought to be when glued, or the showroom is really dry. If you don’t know the numbers, you’re just guessing. This should be preventable.

-- Bob Lang, https://readwatchdo.com

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Chuckt62

1 post in 219 days


#11 posted 01-07-2018 08:34 PM

I had this type of failure years ago when I first started in woodworking. When I applied the finish I failed to do the underside of the table top. Once I fixed the failure and finished both sides of the tops haven’t had a problem.

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Aj2

1576 posts in 1877 days


#12 posted 01-07-2018 08:44 PM

That’s a very fine looking table. I used to make 5 or 6 tables a year but my commissions have dropped out since the big furniture stores have opened up around me. And that’s fine with me since I’m not a production shop. I can say for sure walnut is far more forgiving then Oak even quartersawn. Hardmaple is the most demanding.
I too have a long bed jointer the very best ever made.If I’m not careful I cannot get accurate edges.
Your probably right the wood did not like that spot.
Good luck.

-- Aj

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TheFridge

9841 posts in 1565 days


#13 posted 01-07-2018 09:30 PM

I’d bit for the radiator as part of the problem.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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ColonelTravis

1854 posts in 1973 days


#14 posted 01-07-2018 09:39 PM

Question because I’m curious and simply do not know – if wood glue is typically stronger than the wood itself, which is what I’ve read, why would the split here be at the glue line? Is it because the glue would be getting the moisture more (or faster) than the wood?

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Tony_S

896 posts in 3162 days


#15 posted 01-07-2018 10:05 PM

I’d be betting on a moisture content that was higher than you would typically receive in combination with the heater is the problem. Not to mention, I think you’ve had a harsher winter in New York than typical haven’t you(colder/drier)?
Quarter sawn White Oak is incredibly stable if it’s dried properly, unfortunately it’s one of the most difficult hardwoods to dry properly, as you’ve already found out.

I’d guarantee, that if the edges were straight and true and glued properly to begin with, it’s a moisture issue with the lumber it’s self. It wouldn’t make any difference what type of adhesive you use, if that’s the case.

-- It is the mark of an educated mind to be able to entertain a thought without accepting it. Aristotle

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