Warped tabletop - Woodworking Talk - Woodworkers Forum
Reply
 
Thread Tools Display Modes
post #1 of 22 Old 03-19-2013, 01:01 PM Thread Starter
Junior Member
 
Join Date: Sep 2012
Posts: 27
View cgp4312's Photo Album My Photos
Warped tabletop

I am making a new kitchen table that is solid cherry with breadboard ends when I glued the table top it was dead flat but when I unclamps it it slowly started to warp and is now warped bad if I clamp one side down the other is about 1" off my workbench. Is there any way to fix this and why would it warp like this all my wood was between 5-7% moisture to thanks for the help
cgp4312 is offline  
Sponsored Links
Advertisement
 
post #2 of 22 Old 03-19-2013, 05:41 PM
Senior Member
 
Join Date: Sep 2011
Posts: 26,068
View Steve Neul's Photo Album My Photos
You might try wetting the cup side of the top with water and see if it flattens. If it does I would attach a skirt to the table as quick as possible before it curls up again. Cup warp is normally caused by an imbalance in the moisture content from one side to the other. If it works be sure when you finish the table you seal the underside as well to keep moisture from the air out of it.
Steve Neul is online now  
post #3 of 22 Old 03-19-2013, 07:49 PM Thread Starter
Junior Member
 
Join Date: Sep 2012
Posts: 27
View cgp4312's Photo Album My Photos
Ok I will try that and I also haven't put the breadboard ends on it yet do you think when I do it will help straighten it out or will it just now the ends to
cgp4312 is offline  
Sponsored Links
Advertisement
 
post #4 of 22 Old 03-19-2013, 11:12 PM
Senior Member
 
Join Date: Sep 2011
Posts: 26,068
View Steve Neul's Photo Album My Photos
The breadboard end is suppose to help prevent the top from warping. I would wait until the top is flat before you install them. Anyway when you wet the table it will cause the table to expand a little so I wouldn't fasten the breadboard end just yet. I would just put it on and put a single screw in the center for a couple of days to let the top shrink. Forgive me for saying this but I don't know your experience but the breadboard ends are never glued on. They are just installed with a few screws to allow the top to shrink. If it was glued and the wood shrunk it would cause the top to split. Some folks also elongate the screw holes to make sure the screws don't make the top split.
Steve Neul is online now  
post #5 of 22 Old 03-20-2013, 03:28 PM
Junior Member
 
Join Date: Jan 2013
Location: Broken Arrow, OK
Posts: 11
View oakcutter's Photo Album My Photos
Table Top Warp

I too am in the process of building a table top and am concerned about keeping it flat. My guess is there is a fine line between too much clamping force and not enough. So question is, how does one know what's enough. I have tried glued up panels before and wondered if I was forcing it to warp/bow because of too much pressure. Any thoughts?
oakcutter is offline  
post #6 of 22 Old 03-20-2013, 05:03 PM
Senior Member
 
BZawat's Avatar
 
Join Date: Sep 2012
Location: Wilkes-Barre, PA
Posts: 1,455
View BZawat's Photo Album My Photos
Quote:
Originally Posted by oakcutter
I too am in the process of building a table top and am concerned about keeping it flat. My guess is there is a fine line between too much clamping force and not enough. So question is, how does one know what's enough. I have tried glued up panels before and wondered if I was forcing it to warp/bow because of too much pressure. Any thoughts?
Not to aid in your hijacking of this thread, but I can offer you a few suggestions.
First, the joints between boards in your panel (or tabletop) should fit together with no gaps before they are clamped. If you're clamping tight enough to pull gaps in the glue joints together, you're clamping too tight and it certainly could cause warping. Clamps just hold the panel together till the glue dries.
Second, you should maybe consider using cauls to aid in keeping your glue up flat and properly aligned. They are easily made from any chunky stock you may have laying around. I used spruce framing lumber for mine.

As far as straightening a warped top, good luck man! I've never had any success at it, short of some creative planing haha. But then you lose thickness so...
BZawat is offline  
post #7 of 22 Old 03-20-2013, 09:42 PM
Senior Member
 
Join Date: Mar 2013
Posts: 569
View Smith Brother's Photo Album My Photos
I am betting you will need to cut down the middle of your glue joints and start over.

When clamping, alternate the clamps on both sides of the table, this will apply pressure more equal, and aid in preventing the issue you have.

Personally I have found that bread boards, or end boards as I call them won't solve this issue. The Cherry long boards will move at a different rate as the end boards, and you will probably at some point down the road find gaps, IMO.

Like one said, DON'T CLAMP TO TIGHT. Are you using any biscuits in the boards? I have had good results in burying 1/4" strips of plywood approx. 1" deep in each board, then gluing. It's more work, but has worked well for me.

I wish you well,

Dale in Indy

Last edited by Smith Brother; 03-20-2013 at 09:45 PM.
Smith Brother is offline  
post #8 of 22 Old 03-20-2013, 11:57 PM
Senior Member
 
Join Date: Sep 2011
Posts: 26,068
View Steve Neul's Photo Album My Photos
Quote:
Originally Posted by oakcutter View Post
I too am in the process of building a table top and am concerned about keeping it flat. My guess is there is a fine line between too much clamping force and not enough. So question is, how does one know what's enough. I have tried glued up panels before and wondered if I was forcing it to warp/bow because of too much pressure. Any thoughts?
Its pretty difficult to put too much pressure on a glue up. I've seen guys tighten their clamps and then take a crescent wrench to get a little extra umph on it. That is too much pressure. Normally a good snug is all it needs and try to put the same pressure on each side. The biggest problem in putting too much pressure is squeezing too much of the glue out of the joint which weakens the joint. The most important thing is to make sure the joints fit well before gluing so you don't need to use much pressure to begin with. If your forcing the a bad joint together then that much pressure is trying to pull them apart after your done.
Steve Neul is online now  
post #9 of 22 Old 03-21-2013, 12:27 AM
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 27,615
View woodnthings's Photo Album My Photos
+1 on cuttin' it apart and startin' over

Cherry is some wild wood occasionally and will have a mind of it's own. I agree also that clamping pressure should just be adequate to get some squeeze out with an even uniform glue application. I usually go tight then another 1/2 turn on the pipe clamps, top and bottom about 8" to 12" apart. If you have to muscle it to close the joints, the boards aren't straight in the first place. Rejoint and dry fit again. Alternate cupping grain when possible. I generally clamp up on a flat surface if the size permits, then lift the whole thing off the bench and put the reverse side clamps underneath and snug them up to even the pressure.

When thickness planing wood try to remove equally from both faces to avoid excessive movement. It's nice to have access to a wide belt sander when making a large glue up, door or table. Seek out a cabinet shop or mill and pay for the time on the machine, it's well worth it.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
woodnthings is online now  
post #10 of 22 Old 04-22-2013, 01:46 PM
Senior Member
 
Join Date: Nov 2011
Location: Coastal NC
Posts: 1,160
View HowardAcheson's Photo Album My Photos
How and where are you storing this glued up panel? Is it in a place and position where air can freely get to both surfaces? In other words, is the panel lying directly on another flat surface?

Howie..........
HowardAcheson is offline  
post #11 of 22 Old 04-22-2013, 02:10 PM
Senior Member
 
WillemJM's Avatar
 
Join Date: Aug 2011
Location: Pinehurst, NC
Posts: 1,200
View WillemJM's Photo Album My Photos
Wood unfortunately moves and this can happen.

The way I design my tables is aprons closer to the edges, which would pull an inch flat without a problem.

It is also important to match the grain and growth rings prior to glue-up, which if done right will prevent cupping, as wood movement is not a constant, but can vary within the same species.

Pure mathematics is, in it's way, the poetry of logical ideas. - Albert Einstein.
WillemJM is offline  
post #12 of 22 Old 04-23-2013, 01:23 AM
Making sawdust in MS
 
rayking49's Avatar
 
Join Date: Nov 2011
Location: Philadelphia, Ms
Posts: 4,000
View rayking49's Photo Album My Photos
Quote:
Originally Posted by HowardAcheson View Post
How and where are you storing this glued up panel? Is it in a place and position where air can freely get to both surfaces? In other words, is the panel lying directly on another flat surface?
+1 I try to keep the table top stickered on my assembly table till I can get it installed. That way air get to top and bottom alike.
rayking49 is offline  
post #13 of 22 Old 04-23-2013, 06:51 AM
Senior Member
 
Join Date: Jan 2010
Location: NW Pa
Posts: 2,993
View TimPa's Photo Album My Photos
+2. if it was laying on another flat surface, flip it over and wait. it may likely come back, but usually takes a little longer.
TimPa is offline  
post #14 of 22 Old 04-23-2013, 10:10 PM
Senior Member
 
Join Date: Sep 2011
Posts: 576
View Midlandbob's Photo Album My Photos
Panel warping is going to be from selecting the wrong boards. Some boards are prone to warping as they are cut from too small trees visible by small radius growth rings on the ends of boards. Also beware of uneven growth rings from "reaction wood" which is cut from trees growing in any other than very vertical. Any lean in the tree causes the tree to grow unevenly on one side vs the other.
The most common abnormality is using wood that has not been well or evenly dried. If it has not been equilibrated to the environment it can/will distort/ warp after it has been glued up.
If the warping is too much to easily restrain, you will want to start over changing something significant. Reject any board that has irregular growth rings or has growth rings that are too tight.
As mentioned it is rare to impossible to over tighten the clamping.
Midlandbob is offline  
post #15 of 22 Old 04-23-2013, 10:20 PM
Senior Member
 
BZawat's Avatar
 
Join Date: Sep 2012
Location: Wilkes-Barre, PA
Posts: 1,455
View BZawat's Photo Album My Photos
Quote:
Originally Posted by Midlandbob
Panel warping is going to be from selecting the wrong boards. Some boards are prone to warping as they are cut from too small trees visible by small radius growth rings on the ends of boards. Also beware of uneven growth rings from "reaction wood" which is cut from trees growing in any other than very vertical. Any lean in the tree causes the tree to grow unevenly on one side vs the other.
The most common abnormality is using wood that has not been well or evenly dried. If it has not been equilibrated to the environment it can/will distort/ warp after it has been glued up.
If the warping is too much to easily restrain, you will want to start over changing something significant. Reject any board that has irregular growth rings or has growth rings that are too tight.
As mentioned it is rare to impossible to over tighten the clamping.
I respectfully disagree. Board selection is one possible cause of warp, but certainly not the only one.
And it is definitely possible to cause a panel to be warped/cupped/twisted due to over tightening and/or improper clamp placement and balance.

Perhaps the OP needs to determine exactly which of the factors mentioned in this thread contributed to his top warping before deciding how to proceed in fixing it.
BZawat is offline  
post #16 of 22 Old 04-23-2013, 10:32 PM
In History is the Future
 
firemedic's Avatar
 
Join Date: Dec 2010
Location: South Louisiana - Gonzales
Posts: 6,423
View firemedic's Photo Album My Photos
firemedic is offline  
post #17 of 22 Old 04-24-2013, 12:53 PM
Senior Member
 
Join Date: Nov 2011
Location: Coastal NC
Posts: 1,160
View HowardAcheson's Photo Album My Photos
>>>> Perhaps the OP needs to determine exactly which of the factors mentioned in this thread contributed to his top warping before deciding how to proceed in fixing it.

Too true. There seems to be a propensity for offering solutions before there is a full understanding of the problem.

Howie..........
HowardAcheson is offline  
post #18 of 22 Old 04-24-2013, 10:04 PM Thread Starter
Junior Member
 
Join Date: Sep 2012
Posts: 27
View cgp4312's Photo Album My Photos
Thank you everyone for your response I finally gt around to working in the shop again and I had the tabletop sitting on the floor while I was gone and a lot of the warping left and when I put the breadboard needs on it is almost perfectly flat now thanks for all the responses they were a huge help
cgp4312 is offline  
post #19 of 22 Old 04-26-2013, 12:33 PM
Senior Member
 
Join Date: Sep 2011
Posts: 576
View Midlandbob's Photo Album My Photos
Quote:
Originally Posted by BZawat

Board selection is one possible cause of warp, but certainly not the only one.
And it is definitely possible to cause a panel to be warped/cupped/twisted due to over tightening and/or improper clamp placement and balance.

Perhaps the OP needs to determine exactly which of the factors mentioned in this thread contributed to his top warping before deciding how to proceed in fixing it.
Just what aspect of a glue line is going to cause cupping or warping??????
Unless you think you can clamp hard enough to crush fibres, the glue line is NOT the cause of warping. If you did "over clamp" you would get an angle in the top where the crushing occurred not a gentle curve as is the case with a warp.
An improperly jointed joint also would have an angle NOT a curved surface/plane.
Studies done and reported in FWW showed than conventional clamps do NOT have the force to over clamp. Maybe if you put a clamp every inch!
Wood deforms due to it's hygroscopic nature of taking on or losing water depending on the humidity and the fact that the dimensional change is different in the tangential vs the radial direction.
Boards have built in properties/tendency of warping that vary from board to board. Board selection is critical.
A current FWW has an article on building flat doors which discusses the importance of wood selection to ensure flat panel glue ups.
Certainly Temporary warping can be caused by uneven changes in moisture like only finishing one side of a board or exposing one side to higher humidity than the other but warping is caused by undesired wood deformation due to changes in moisture content!!!
Midlandbob is offline  
post #20 of 22 Old 04-26-2013, 09:30 PM
Senior Member
 
BZawat's Avatar
 
Join Date: Sep 2012
Location: Wilkes-Barre, PA
Posts: 1,455
View BZawat's Photo Album My Photos
Ok :)
BZawat is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Warped Poplar 1958 TableTop - How can I flatten this? keith204 Design & Plans 9 05-23-2019 04:38 PM
Tabletop rayking49 Wood Finishing 5 12-16-2012 10:41 AM
Another tabletop question Better Place General Woodworking Discussion 4 09-07-2012 09:41 AM
Tabletop buttons. dribron General Woodworking Discussion 4 07-10-2011 10:32 PM
Tabletop Question debellpepper Joinery 10 03-16-2011 12:13 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome