Curling & cracking


Help! I've been building a dining room table that is 5ft square made of hard maple. I've followed the directions in my FWW mags and books to the letter. I've alternated the grain but with the climate change, my table top has curled up ALOT. Now there are 4 separate areas where the 6inch wide boards, which were biscuited, glued, and clamped, have become separated at the ends, perhaps 1 to 4 inches into the table from the edge. A gap exists between 1/16 and 1/8". Now what? The only thing I can think of is to somehow get glue back in this tiny crack and then re-clamp. Please offer me your good suggestions. Thanks, -Clueless
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Stan wrote:

Stan:
People would need a lot more information to help.
How thick is the wood? What type of glue? How much climate change? What was the humidity change -- best guess... Kiln dried wood? Air dried? (And if so how long (i year per inch?)...) Did you let the wood sit in your workshop before you cut and glued? How long if so? How long did it take to come apart? Immediately, a week? Is it (was it) installed in the frame of the table or just sitting out somewhere...
It does sound like a moisture/humidity issue -- not that I have ever made this kind of mistake -- just heard about it. :-))
I think my maple table is narrower boards.
You'll get lots of opinions...
--
Will
Occasional Techno-geek
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Boards are 1-1/8" thick. Glue is Titebond III. Current measurement in my shop is ~40% Rh and in the winter it was in the 20s but it has gone higher in the past week. Wood was supposedly kiln dried but probably sat in an open door barn for years. It sat in my shop for months before planing and sat there for months after being planed and jointed before I glued it up. I noticed a very slight crack weeks ago but just noticed the big ones yesterday, along with the severe curling. It is just sitting out on my work bench. Stan
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Stan wrote:

Stan:
Hope you see George's answer by now.
Also - I think you are saying that you glued it and it sat for "quite a while"???
BTW -- Seasonal change is what you mean. (Climate is long term... :-) ) FWIW
After you look at George's response think about.... Is it possible that you had a number of factors at work?
A) it was "too cold" b) Clamped too hard (Just tight enough to squeeze excess glue is best b) The glue was old or bad or maybe not quite as good as possible... c) A quick moisture change along with the above
It seems like "too much" of a failure considering that you tried to take reasonable care.
Maybe your timing on the gluing was just terrible -- i.e. way too cold --- and then the seasonal change hit and you got too much stress.
Also -- If I cannot immediately smooth and finish these types of pieces, I have taken to sealing the wood ends quickly after gluing up long pieces -- just to make sure that "rapid" humidity changes don't cause problems.
--
Will
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Will, When I glued it up was in the middle of winter (very cold here near Lake Ontario), but we experienced a couple of days of warm (above 60F) weather so I took my chance and glued up. The harsh cold that followed may have caused stress. The glue was brand new. I may have clamped too hard.
I'm thinking about either taking a syringe or a small pump with a needle that is used to inflate balls and tires and putting glue into it, inserting the needle in the crack, and then pumping in the glue and then clamp. Another thought is to drill a small hole from the side or bottom and insert the glue enough to spread it around and then re-clamp. Stan
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Stan wrote:

I am about 70 KM north of Lake Ontario so I understand. Brrr! We get large temp and humidity swings as well. During the winter my wooden planes closed up on the blades. Had to widen the mouths. 20% humidity as I recall.
My recommendation is to take the other posters recommendations very seriously.
Rip it down the glue line and do a complete re-glue. An afternoons work and you should be out of the problem. I suspect that it will not clamp tight right now. You can test to see. Never had any luck myself with what you are suggesting. Also -- when you separate the pieces you may find that a piece is twisted -- then the problem would be obvious.
If you can see a gap in an otherwise beautiful table in a couple of years it will just p**s you off no end. LOL
Maybe George will also say something -- he seems to know what he is doing... :-)
--
Will
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Thickness - immaterial as long as acclimatized Glue - Certainly Humidity change - had to sometime, will again Kiln/Air dried - immaterial, so long as it _was_ dry Acclimatized - possible problem if it wasn't stickered, leaving some wood much wetter Speed of Self-Destruction - possibly significant
When you say 4" from the ends of the glueups - assuming glueups, no breadboard - then I tend to think that the biscuits are centered about inch five, and you've had glue failure. If it were cold when you glued up, you might have problems. If things have become damp since, especially if the parts that have separated have been near the floor where it changes most, might also have a problem. If boards were poorly joined and squeezed into submission, especially hard maple, which doesn't soak up glue much, could also be a player.
Now, if the wood was inadequately acclimatized, you might have some problems as well. Tension relief on the drying boards might have pulled them away from the others - but only if the glue failed.
Alternating "smiles" are really not important. More important is broad to broad grain, quarter to quarter.
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Stan wrote:

I seriously doubt you can re-glue as is. If it were me, I'd rip into 3" planks, make sure the edges were straight and true and glue the lot up again.
-- dadiOH ____________________________
dadiOH's dandies v3.06... ...a help file of info about MP3s, recording from LP/cassette and tips & tricks on this and that. Get it at http://mysite.verizon.net/xico
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Don't panic. You still have most of the wood available for thios glue-up. Obviously the wood is just still stabilizing. You need to start over. Really no other approach.
Just rip the boards right on the glue lines. Re flatten, re-edge. Get very straight edges so the boards flush up clean all along the edge even before clamping. Re-glue and clamp.
You need to make sure you use enough clamps. However if the edges of the wood are good you don't need that much pressure. You can map the clamping pressure coverage by imagining a line extending at 45 degress to each side of the clamp bar from the face of the clamp towards the joined edges. The clamps should be close enough together so the pressure zones overlap. So wider boards actually require less clamps because the pressure zone expands the farther you get from the clamp face. I hope that makes sense.
BW
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Stan wrote:

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Stan, In addition to the other suggestions, if you didn't apply equal amounts of finish to all sides, that could have something to do with it.
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Second or third mention, but untrue. It may cause bowing of the entire top - usually does, but won't cause failure of the glue at the ends of the boards of a glueup.
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OK I think I've finally figured out why my tabletop split apart. I recently ripped it into individual boards again per your suggestions. I then re-jointed all the edges. This time I noticed that if one end was held flush against the mating board, there was a tapered gap increasing in size towards the other end. I soon determined that this was due to the relationship between my jointer blade and the outfeed table. I made an adjustment to this. In the end, I adjusted the gibs for both the in and outfeed tables to the point now where, using a VERY flat, thick and wide, 4ft starrett ruler, I have the in and outfeed tables adjusted within microns of each other and the relationship to the blade is practically perfect (I spent 5 or 6hrs doing it--I hate giving up!). Now when I joint the two mating surfaces, I get a 1/64inch gap in the middle but the ends are flush. I should say again that my boards are 5/4 hard maple, 5.5inches wide and about 57inches long.
Now my question to you JOINTER EXPERTS: Is this gap simply inevitable, given that my combined in and outfeed table length is about 47inches and my stock is about 10inches longer than that or is there something else I'm overlooking?
I have the Yorkcraft 6inch wide jointer which is the same model as the Delta. Stan
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Not a jointer expert, but six foot on my old 4" Rockwell (30") wasn't a chore. Eight on the 6" Jet isn't either. Watch your hand technique. After the initial half foot passes the blades, there should be a hand over that position as much as possible while feeding..
You compare those edges to the Starrett, or just to each other?
I'll let an expert chime in with praise for sprung joints.
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Stan wrote:

...
If the edge is concave, the outfeed table is just a tad high relative to the knives. It should be possible to get essentially perfect contact on a piece of that length. If the outfeed table is adjustable, the final tweak should be nothing more than a nudge and test cut or two. As I recall the Yorkcraft is a Delta clone so that <should> be the case.
Did you check that the infeed/outfeed tables are actually parallel to each other, I presume? That also could be a cause if the ends droop relative to each other.
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<snip>

I believe that if you leave these boards overnight in my shop, and measure again in the morning, you will get a different reading.
1/64 inch over 5 feet ought to be within woodworking tolerances.
Go Cougars!
Patriarch
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Stan wrote:

Over that length, you should be able to do better. But 1/64 isn't a crisis, IMO. Especially in the middle of the board, wouldn't want it at the ends.
-- dadiOH ____________________________
dadiOH's dandies v3.06... ...a help file of info about MP3s, recording from LP/cassette and tips & tricks on this and that. Get it at http://mysite.verizon.net/xico
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Stan wrote:

Several other pretty good responses...I'm leaning to that you may not have had as straight an edge as desirable as well as the temperature may have caused glue failure. Did the material have time to acclimatize to the temperature before your glued it or was it still cold? It's not the air temperature that's important as much as it is the material temperature.
Also, if there was any visible gap or "rocking" that you had to pull up w/ the clamps, that's not an adequate fitting prior to gluing--you need it tightly fitting all along the length simply by hand w/o relying on clamps to close any gaps.
The bowing may well be compounded by having left it laying flat on the bench so that air circulation has been restricted on the one side relative to the other--similar effect as having only finished one side.
Since it's still a new project, the suggestion to re-glue is probably the best route to a good end product as it's unlikely you'll get a good bond again and if it was, indeed, glue failure from cold weather, it'll likely fail further sooner than later--and it would definitely be a shame if that were just after you were completely finished and set it inside... :(
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