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Hello All--I have an issue with a table top made of Chinese Elm. It was originally a door, converted into a table in either Thailand or China, and was a lovely piece of furniture and was perfectly flat when still in the tropics. It is made of 2x6 (approx) boards, joined with either glued, biscuits, or both. I don't know which was used. Now that it has been abruptly moved to New England and introduced to low humidity in a winter house, you can see what has happened to the top.

Any ideas how it can be leveled? I have a relatively small workshop but do have a number of pipe clamps. Thanks!
 

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How long has it been in your home? If you haven't had it very long it might spring back a little during the summer. either way, it looks like thats alot of dip in the middle. Is there any play inbetween the boards, as in would taking it apart be possible? you might resolve some of the problem by running a hand plane where the joints were. I haven't seen such a bow in a table and I'm sure someone much more knowledgeable than me will have a solution because all I can see to do is hand plane the outside top edges until it's level, but that would creat a huge visual difference.
 

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I unfortunatly have a lot of experience with Indonesian furniture as I do a lot of repairs for a furniture import comp near my shop.

I have a few questions to start with.

What's your skill level? Are you comfortable with and have the tools to remove the top and rip it down to planks again and joint it back?... This is the best way but can be last option.

Is the entire top finished?... Top and bottom? What is it finished with?

How long has it been in it's new enviroment? How quickly did it cup?

Tom
 

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bowed table top

Different people will offer different advice based on their experiences/skills and what will be the best option for you will be your decision.
From looking at the photos, it appears that your course of action may be to remove the top and rip it down the length into narrower strips and use dowels or some type of a spline joint and then reattach it to the base with a caul across the under side.
Of course this is always easier said then done, I did it to a 7' long X 3' wide X 1 1/4" hard maple table top from a postal sorting desk my neighbor gave me that was 6 months older then me and I am not far from the rocking chair...
 

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I unfortunatly have a lot of experience with Indonesian furniture as I do a lot of repairs for a furniture import comp near my shop.

I have a few questions to start with.

What's your skill level? Are you comfortable with and have the tools to remove the top and rip it down to planks again and joint it back?... This is the best way but can be last option.

Is the entire top finished?... Top and bottom? What is it finished with?

How long has it been in it's new enviroment? How quickly did it cup?

Tom
I agree, one option would be to cut, joint the edges, and reassemble. Without knowing how long its been in the new environment, it may come back on its own. Now that would be a stroke of luck.

Of course, cutting up, the wood should be stripped, acclimated, jointed, and with all that the pieces could take their own course.








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All--Thanks for your quick response. To answer your queries, I am an enthusiastic novice when it comes to woodworking. I am eager to try different techniques so, I would not be reticent about taking the table top apart and ripping it to planks, running them through my jointer, and reassembling it using a spline or biscuits.

It went from pretty flat to quite bowed in the time span of Jan 10-Feb 11. We keep our house at about 45% humidity. The bow was not severe last summer but it was noticeably more bowed than when we were in the tropics. It is solid with no play in the joints. It is not finished but rather rubbed with beeswax. It presently has five cauls on the underside. The top measures 100" x 42".

I appreciate your attention to my matter.
 

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where's my table saw?
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All--Thanks for your quick response. To answer your queries, I am an enthusiastic novice when it comes to woodworking. I am eager to try different techniques so, I would not be reticent about taking the table top apart and ripping it to planks, running them through my jointer, and reassembling it using a spline or biscuits.
I appreciate your attention to my matter.
Hey good for you, jump right in!:thumbsup:
The cauls or underside braces may be a part of the issue as well, I donno? if they are warped.
There are some severe checks goin' on also. You should look at the end grain and see if it's cups up or cups down or both...which would be best, but if you're takin it all apart it won't matter how it was, just how you put it back.
Which now brings up how are the cauls attached... screws? That will mean you can't flip the boards over without the holes showin....darn.
If you are going to rip them into lengths I'd like to see widths of around 3" - 4" after jointing. The next issue will be reassembly, there are 2 ways:
1. a large flat surface, lay them out, glue them up, clamp from both sides, under and over, alternating pressure evenly.
2. glue them up in smaller width panels 4 or 5 at a time with smaller/shorter clamps, then assemble the panels together 2 at a time.
What you're hearin here is ...clamps...lots of 'em. There is a cheap solution if you don't have that many...redi rod threaded , in 1/2" x 36" lengths. You can make individual clamping frames, 2 rods, 2 wooden plates and 4 nuts and washers per frame, somewhat like this only separated and double sided: :thumbsup: bill




Additional clamping jigs: http://www.woodcraft.com/Product/2000321/1858/WoodRiver-Clamping-System.aspx

http://www.ptreeusa.com/panel_glue_up.htm
 

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andoverma said:
All--Thanks for your quick response. To answer your queries, I am an enthusiastic novice when it comes to woodworking. I am eager to try different techniques so, I would not be reticent about taking the table top apart and ripping it to planks, running them through my jointer, and reassembling it using a spline or biscuits.

It went from pretty flat to quite bowed in the time span of Jan 10-Feb 11. We keep our house at about 45% humidity. The bow was not severe last summer but it was noticeably more bowed than when we were in the tropics. It is solid with no play in the joints. It is not finished but rather rubbed with beeswax. It presently has five cauls on the underside. The top measures 100" x 42".

I appreciate your attention to my matter.
Glad you added that last pict. Are the cauls one piece across? I'm pretty certain the movement involves the cauls.

I would be very interested to know how the stop would respond to removing the cauls and being allowed to sit a week or so to stablize... Prob is it's catch 22... It could result in the table cupping even more...

One option would be to remove the cauls and over a couple days of progressive pressure get it clamped straight and leave it a week or two. Sanding before hand would help too as it would open the pores in the wood and help it to eqaulize more readily.

Your the one there with your hands on it... What are you thinking?

My absolute biggest fear would be incurring actual cracks in the top if I was undertaking this myself.
 

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where's my table saw?
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How is the top attached?

there seems to be no attachment method visible in the
photo:




If it's just resting on the frame, that is great, and will make the next step a whole lot easier. As was suggested above the caulks might be more of an issue than an warping in the planks. If you remove them any they hold a curved shape there's your answer. You can/should still rip the planks to minimize and further issues while it's apart. That's what I would do seeing the severe checking. So, you can replace the cauls or flip them over if they straighten out, but the chamfered ends will be an issue. They are really attached in the wrong plane to be beneficial, the deep edge should be vertical, not horizontal as is. JMO
At any rate get it apart, check it out and see what gives. ;) bill
 

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Bill and Firemedic,

Thanks for your continued input and support.

In studying the top some more, I notice that the planks in the top have various widths but, nevertheless, I am going to proceed with ripping it into 3-4" planks and reassembling it with spines. Any reason I should use biscuits instead? They would be easier.... If I do go with splines, is there a specie of wood you would recommend? In looking at the table, I think I was wrong with Chinese Elm. That's another table in my house. The subject of this thread is made of teak.

After reading your comments, I further examined the table and it has two layers of planks, as you can see from the first picture below. The bottom layer is made up of narrower pieces and they don't travel the length of the table, so I can't just rip the top and turn some of the planks over. The top layer, which is an inch, has wide planks, ranging from 7-8". This is leading me to the thought that the issue is with the width of the top planks, coupled with the adhesive failure. The table is assembled with brads and glue (hooray!) and the top just rests on the stand. The second photo shows how one of the cawls is coming apart from the top. This is the most extreme case. From what I can tell, all of the cawls are embedded within the bottom layer of wood. By the fact that it is coming apart, makes me think that while there is some degree of warping because of the change in environment, there is an adhesive failure and that if I ripped the top down to more manageable 3-4" planks, sanded all surfaces to open the pores, and re-glued it using splines, I would be doing the best toward restoring it to 180 degrees.

Please let me know if I am way off base. Otherwise, wish me luck and I will certainly get back to you with my results. Be patient though, I have a lot of chainsaws in the air right now. Cheers!
 

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just found this thread. interesting real life instance of what happens when wood movement is not allowed for.

my guess is that the battens (cauls) on the underside aren't causing anything, they seem to want to keep straight. i don't think thin boards like that wanting to bow would be enough force to put that much curve in a panel as big as your top anyway. of course, they never ever should have been glued on along the entire width of the table, but you'll fix that.

i think the culprit is the second layer of wood glued to the underside of the top, combined with lack of a "real" finish. the top side of the top, with just beeswax on it, is releasing moisture like crazy and therefore shrinking (hence the curve upwards). the underside of the main top (the 7-8" wide pieces) can't breathe at all since it's glued to that second layer of thinner boards so there is no balance in moisture release/intake.

the second layer of thinner boards has the opposite thing going on but it's thinner, therefore creating less force, so the top layer wins out. my theory anyway :blink:

i would begin by removing those battens if possible. rip the top down into boards along the glue lines of the top layer of boards, the 7-8" pieces you mentioned. (be aware when ripping the top down into boards that there are probably opposing forces at play within the top, and you will be releasing some of them. wood with stress in it behaves funny sometimes. if possible, it may be best to rip the top in half, then work on breaking down each half. if the curve of the top is such that the edges are higher than your fence, make a tall auxiliary fence. use clamps or brads or screws or double sided tape to attach spacers to the high edges so they touch the saw table so the whole thing is stable and doesn't want to rock while cutting, or fall apart when 90% of the way through the cut).

wipe the boards down well with denatured alcohol to draw out as much wax as possible and sand them. then let them sit and keep watch. either they will keep getting worse or they are done moving.
after a while (couple weeks, maybe longer) if they seem to have adjusted and aren't moving anymore, you can address each board before reassembly. if they are really cupped, you may have to rip them each in half before jointing but if they are in decent shape you may be able to just re-joint the edges and glue it up keeping the original wide board look of the top.

then, i'd finish it top and bottom with tons of layers of thinned out tung oil ragged on/off so it really soaks in deep, then top coat with something easy to apply and touch up like waterlox. really drag out the finishing process; lots of thin thin coats, and lots of cure time between.

sorry for the long winded post! hope it helps.
 

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In studying the top some more, I notice that the planks in the top have various widths but, nevertheless, I am going to proceed with ripping it into 3-4" planks and reassembling it with spines. Any reason I should use biscuits instead?
I would not use biscuits or splines. I would remove the cauls, and rip the boards at their seams. Then I would split the boards in half. Since the curvature is a gradual one, and it looks like it's with some from each board, the smaller they are would help minimize the existing condition.

Then I would joint each board to get a perfect 90 degree edge. You also want to get all the wax/oils off the wood. Whatever it's wiped down with (alcohol, lacquer thinner, or acetone) will dissolve some of that topcoating into the wood. Hopefully, with several applications, it will reduce it.

In reassembly, just to use glue and clamps and cauls, alternating them top and bottom, and getting even clamp pressure across the wood. It might be easier to glue up 2 or 3 at a time to get good alignment. For a finish, I might use a wiping version of a varnish oil mix.







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I concur with Mr B & C-man... They're pretty much on the same track.

Don't use biscuits... No reason to. You could go splines if ya want, it's ur table, but not really needed.

I would try to keep the planks as wide as possible to keep things simpler so I also recomend ripping at glue lines. You could consider passing them through a thickness planer to minimize the cupping while keeping wide boards.

And I agree with Mr B's theory on why it's moving. Hopefully once it's resolved you won't move back to the east! Lol
 

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I concur with Mr B & C-man... They're pretty much on the same track.

Don't use biscuits... No reason to. You could go splines if ya want, it's ur table, but not really needed.

I would try to keep the planks as wide as possible to keep things simpler so I also recomend ripping at glue lines. You could consider passing them through a thickness planer to minimize the cupping while keeping wide boards.

And I agree with Mr B's theory on why it's moving. Hopefully once it's resolved you won't move back to the east! Lol
+1 for me, also clamps, clamps and more clamps
 
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