s1nglemalt Posted June 3, 2014 Report Share Posted June 3, 2014 I am building a live edge walnut ~8/4 bookmatched dining table and one of the ends is slightly warped so it bends up to the eater about 1/2" over 34" - mainly on the photo's right side. It may be noticeable by woodworkers, or maybe not. I am using beefy 4" tube metal legs with 7 screw slots along the top. If I crank down on the screws will that flatten the table? Or is that disaster waiting to happen eventually? In the photo, the table is obviously upside down, and the base unit is tapered is around 1/2" from the table at its max warp. Would you ever consider routing a 4" slot in the middle of the table bottom where the top base plate will screw into the walnut? This could eliminate some of the rocker, but is this a lame fix? Would an even dumber fix be to use washer above the plate when I attach it to make it flatter? I need your help. What do you think? Quote Link to comment Share on other sites More sharing options...
..Kev Posted June 3, 2014 Report Share Posted June 3, 2014 Do you have the tools to get it flat? Ultimately, that's your best option. Quote Link to comment Share on other sites More sharing options...
Dave H Posted June 3, 2014 Report Share Posted June 3, 2014 Is the warping at the glue joint? if so cut the table apart at the glue joint re-joint the edges and re- glue the sucker back together clamping some 2x4 cauls across the top to keep the glue joint from warping again. Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted June 3, 2014 Report Share Posted June 3, 2014 I think you will have to plane it flat, as trying to force it flat is likely to crack it. You will lose less thickness if you saw it apart, plane both pieces flat and to equal thickness, then glue it back together. Quote Link to comment Share on other sites More sharing options...
..Kev Posted June 3, 2014 Report Share Posted June 3, 2014 Without know what tooling is available, there's a few different options. Wtnhighlander's option is viable but, a lot of work.. The router sled is another option.. Quote Link to comment Share on other sites More sharing options...
s1nglemalt Posted June 3, 2014 Author Report Share Posted June 3, 2014 After 30 minutes of handplaning the middle portion of the bottom of the table, the metal base went from 1/2" off, or away from, the table to about 1/4". Progress. I knew when I had these planed, this would be an issue, but I sacrificed overall thickness for perfect square. This is a unique table, with live edge and some other non-traditional things going on. I may break out a router sled. At what point will gravity take over, if at all? Assuming a 80" x 26" 8/4 table weighs, ~100-200 lbs, will an 1/8 gap be closed with screws and gravity pushing the heavy table onto the metal legs? Quote Link to comment Share on other sites More sharing options...
Coop Posted June 3, 2014 Report Share Posted June 3, 2014 There are others here that know a whole lot more about this than me but If it were mine, I would recess the flat bar connected to the legs in a shallow dado and hand plane the top to flat. 1 Quote Link to comment Share on other sites More sharing options...
Tpt life Posted June 3, 2014 Report Share Posted June 3, 2014 Gravity may never fix that. Quote Link to comment Share on other sites More sharing options...
Barron Posted June 3, 2014 Report Share Posted June 3, 2014 It would not surprise me that the metal will deform to match the top vs the other way around. Quote Link to comment Share on other sites More sharing options...
..Kev Posted June 3, 2014 Report Share Posted June 3, 2014 If the top is flat, you may be able to mortise the base into the bottom and hide some of that? Quote Link to comment Share on other sites More sharing options...
DaveT Posted June 4, 2014 Report Share Posted June 4, 2014 Looking at the picture you posted, Baron is right. That metal will bend to match the wood causing your legs to be splayed out. You're going to have to get it flat by either planing or rebating. Quote Link to comment Share on other sites More sharing options...
s1nglemalt Posted June 4, 2014 Author Report Share Posted June 4, 2014 To add context, the metal base is actually 1 piece. It is a trapezoid about 28" tall and 26" wide at the top and 24" wide at the bottom. I doubt it will fail but I am leaning towards getting the roger jig to rabbet the base top. Quote Link to comment Share on other sites More sharing options...
krtwood Posted June 5, 2014 Report Share Posted June 5, 2014 I've heard of flattening cupped slabs by putting them on the lawn in the morning, concave side up, where the sun will hit it. The dew on the grass makes the bottom side want to expand while the sun dries out the top side making it want to shrink. Voila, flat slab. Supposedly. I'm skeptical because even if it works it's going to want to go back to equilibrium and if it was cupped at equilibrium it's just going to go back the way it was but if you get it screwed down flat then maybe you force it to a new equilibrium. Quote Link to comment Share on other sites More sharing options...
Rick A McQuay Posted June 5, 2014 Report Share Posted June 5, 2014 I've heard of flattening cupped slabs by putting them on the lawn in the morning, concave side up, where the sun will hit it. Concave side down so it will absorb moisture and expand. OP, have you considered there may be a reason the wood cupped? Did you apply finish to only one side? Did you have it laying flat on a workbench or floor? Those things will cause a tabletop to cup or bow. Cutting off air circulation to one side causes that side to gain or lose moisture at a different rate than the other side, causing the wood to move unevenly. Quote Link to comment Share on other sites More sharing options...
s1nglemalt Posted June 6, 2014 Author Report Share Posted June 6, 2014 The wood is cupped on one tail end only. It is a big slab at 80" by 36" book matched. I would like to rout a slot on the bottom only for 1/4" and just deal with a minor warp. It is such an interesting table I think people will let it slide. This is not a normal table. It is a one off live edge. If this were not live edge I would have solved this on the planer or wide belt sander. Perfection is the enemy of good enough when it comes to unique table tops? Quote Link to comment Share on other sites More sharing options...
wdwerker Posted June 6, 2014 Report Share Posted June 6, 2014 I have done some tops close to this size. The wood will manage to bend the thin steel connecting the legs. Personally I would rip the center seam out and re-glue it. I you want to avoid that route a groove for the center of the thin steel crosspiece, maybe shim the ends at the legs a 1/16 or so max. As to the flatness of the top if it's within an 1/8 in 80" length you should be fine, maybe a 1/16 on the width. The thing people will notice is the twist , probably similar tolerances on that as well. The higher the gloss of your finish the more evident the cup and twist remaining will be evident. Whatever finish you use do the edges and bottom just as many coats as the top, this will balance things out somewhat. All that being said wood that size is going to move with the seasons and humidity changes . Don't be surprised if it changes a 1/4 to 3/8 over a year. To keep it flat would take a 3 or 4" tall steel frame . Another concern is mounting. Widen the mounting holes at least triple the diameter so the wood can expand and contract in width. Quote Link to comment Share on other sites More sharing options...
deke Posted June 6, 2014 Report Share Posted June 6, 2014 Many others have good advice here, but I'll just add this. Take your time and do it right. You'll get it. This is coming from a guy who has learned the hard way to not force things, take sort cuts or rush. It never works and you will look at that end the rest of your life and say. "If only I had done...." Besides, think of all the exercise you could get from hand planing that thing! Quote Link to comment Share on other sites More sharing options...
Trip Posted June 7, 2014 Report Share Posted June 7, 2014 ==>Personally I would rip the center seam out and re-glue it. +1... That's the right way to solve the problem... No question. There are really only two viable solutions that will leave you with a table you'll be happy with: 1)Rip it, take the slabs to a cabinet shop, pay $25 to have the slabs run over the jointer, planer and widebelt... Done. 2)Plane it flat. You can hide tilt/twist using the dado/shim approach -- it works... But... I've gone down that rabbit hole -- and can be a deep one: Shim, mark, route, chisel, test... shim, mark, route, chisel, test... repeat until frustrated... Don't get me wrong, you may get it in one pass... Well maybe two ... But the last time I used that workflow, it took me five or six passes --- and I was on the verge of throwing some tools... ==>The thing people will notice is the twist Exactly... Folks can detect even small amounts of wind. It you put it out there with twist/wind, you won't be happy in the long-term. 1 Quote Link to comment Share on other sites More sharing options...
KatD Posted November 18, 2019 Report Share Posted November 18, 2019 I also made a live edge table- a slab of several hundred year old kiln dried Florida Cypress, 32"'x 6', a beautiful bark edge and the other edge had gorgeous burn marks that I cleaned and saved the contours. After weeks and weeks of sanding, varnishing 20+ coats to the top, I only did 3 coats on the underside. Huge mistake. It has warped significantly. It seems like it happened overnight! Almost a year of perfect table and then a huge swale along the middle. I was shocked to see the force of it bend the steel bands to the table base. The table has now been laying upside down now for nearly 8 weeks with 400+ lbs of weight in the middle... no movement. I can still slide the fat end of a table knife under the curve. Next step is to experiment with a "v" cut on the underside length to let the slab have the space to snap back- and then fill the new -bound to happen- crack on the top side with epoxy and metal/brass dust. Any other suggestions?? The table base looks nearly identical to the original poster. Quote Quote Link to comment Share on other sites More sharing options...
..Kev Posted November 18, 2019 Report Share Posted November 18, 2019 This looks to me like the wood wasn't allowed to move. The lag holes in the steel legs don't look slotted? You have to allow the wood to move or this will certainly happen, especially on a piece this large. As for the fix, I would have to seriously consider cutting the table in half length wise, reflatten the 2 halves and then glue it back together. Just remember to allow for wood movement when attaching the legs. You can still tighten the bolts down but, create slots in the steel that go across the grain of the wood. Make the slots pretty wide as it's obvious that this slab moved a lot! Use washers on the bolts if the head of the bolt is a little too small for the slot you cut. For the record, I think this has more to do with not allowing for wood movement than it does your finishing regimen. Good luck! Really nice table! 1 Quote Link to comment Share on other sites More sharing options...
pkinneb Posted November 18, 2019 Report Share Posted November 18, 2019 Wow that is a lot of movement but at least it went that way and didn't rip the table apart. See Kev's post above for the fix Quote Link to comment Share on other sites More sharing options...
drzaius Posted November 18, 2019 Report Share Posted November 18, 2019 The fact is that the wood had not reach moisture equilibrium with its environment. Your finishing had nothing to do with the warping, I believe. The slab has dried out significantly since the table was built, as is indicated by the way it shrunk in width, bending the steel. If your finish was a factor, it would have dried out on the underside more quickly, forcing a warp in the opposite direction. So, what to do now? I could be put in a humid place & return to its newly built state, but that may no be enough. I think that the slab, kiln dried or not, was pretty wet inside. It took a lot of movement to bend the steel that much. And moving it to the Amazon probably isn't practical anyway. Or the slab could be ripped in two, both halves flattened & the edges jointed square & then re-glue. You'll loose a wee bit of table width & thickness, but it wouldn't be much. Quote Link to comment Share on other sites More sharing options...
Mark J Posted November 18, 2019 Report Share Posted November 18, 2019 I think you should unscrew the steel frame from the bottom of the slab. At this point that steel is bent and is now resisting the slabs further movement. Don't expect the slab to suddenly return to flat, it's like ..kev and drzaius said, but the steel frame is doing nothing for you at this point. And if there's any hope of savaging the frame it will need to be off the slab to assess and address. 1 Quote Link to comment Share on other sites More sharing options...
drzaius Posted November 18, 2019 Report Share Posted November 18, 2019 I theory, the steel is helping to force the warp, but I bet removing it won't help much, if any. The forces required to bend that steel are minor compared to the force of wood trying to find its 'happy shape' with moisture changes. But changing the mounting method to one that allows for movement is certainly necessary. Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted November 19, 2019 Report Share Posted November 19, 2019 To avoid having a visible glue line on the top surface, you might remove the base, then cut a series of saw kerfs on the under-side, length-wise, and about 3/4 of the way through. Center them over the cup, and space them closely enough to let the slab relax onto a flat surface. Then fill the kerfs with epoxy. This is really not as good as ripping and re-flattening, but keeps the visible surface grain untouched. 1 Quote Link to comment Share on other sites More sharing options...
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