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Help, my newly glued table top warped!

8K views 42 replies 20 participants last post by  farmfromkansas 
#1 · (Edited by Moderator)
Worst fears just came true. This ash wood has been sitting in my garage for about a year; over the last couple of weeks I have milled the boards flat and square and glued the table top together over the second half of last week. I glued it up in parts on Tues-Thurs. I sanded it flat on Friday and did some touch up sanding with a belt sander on Saturday. It's been sitting in my garage waiting to cut to size and do the roundover before bringing it in the house for finishing. I literally checked it this morning on my way to work and all was well. I came home this evening and to my horror it is warping up. All this in less than one day!

Wood Flooring Floor Rectangle Hardwood


Table Wood Desk Workbench Floor


It is most pronounced on one edge. Is this something that can reversed? I thought by leaving it elevated on those planks it would allow air flow on both faces and be somewhat stable. Would it help if I let it rest on the other face? If I misted the problem area? Do I just have to cut that part off?

I'm so angry right now, to have it wait until I glued it up and sanded before it warps, literally days before I bring it inside.
 

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#3 ·
Try bringing it into the house for a few days. I store wood that I'll be making furniture with in the house because that's where it will end up. I only take it to the garage to work on.

We've all had this happen. This is how I try to prevent it:

When I get it home, I only mill rough stock to remove the sawmill marks. I let it sit in the house for a couple of weeks per inch of thickness. Then I mill it to almost the correct thickness and let it sit in the house again. For tops like yours, I'll then glue up panels and then mill to final thickness. Then do final glue up.

Narrower boards glued up with bark side facing alternate directions helps keep things flat as well.
 
#4 ·
I'll leave them in the clamps till just before sanding and finishing. Sometimes there in there for a werk.

You can try the methods mentioned and you might also put them in the clamp in a reverse warp.

How wide were the boards glued together?
 
#6 ·
It will be interesting to see what happens, I suspect that you are out of luck. Several years ago I had some TG hickory flooring that a neighbor gave me. At the time I was living in AZ and the wood was about 2 years old. I cut the T&G off on my table saw then ensured there were no nails. Now I planned both sides and stacked it on some shelving for about a year. I then decided to make a small table, selected the desired wood, glued up the pieces, and let it set clamped up for a few days (I was in no hurry to finish the project and had other things to do). I removed the clamps and made the table, at this time all was OK. About a month later I noticed that the table had a significant warp.

I never did determine why the wood warped. Possibly the grain of the wood was the issue, whatever it was a bust.
 
#7 ·
I agree with whope, bring the top inside where it's final destination will be. I store all my parts In my house when working on a project. The weather is very humid in my area this time of year. It can be a pain moving pieces back and forth, but it helps. You likely opened up the surface to gain/lose moisture when sanding. I have the same issue when re-sawing for book matching. I have to re-saw to a rough dimension, bring inside and let them acclimate before final dimensioning.

I have had success by wetting the cupped side and placing the cupped side down on a flat surface with some weight placed on top.
 
#8 ·
Differential drying often causes that when you lay a glue up like like that on a bench overnight. In your picture you have it sitting on some stickers and that is usually enough to prevent that from happening. Storing it upright and leaning against the bench or a wall is usually better. A little heat on the convex side may flatten it back out but don't leave it in the sun too long or it could warp the other direction.
 
#9 ·
Travis: You're not going to like this, but if your photo is representative of all the boards in your top, I think you should rip every board in the top in half and re-glue. I haven't seen a reply to the question "how wide are the boards?" but the photo you show makes me think they're are more than 6" wide. Unless you have some old growth lumber milled from BIG trees, you'll always have warping problems with boards that wide.
You need to interupt the growth rings, and glue each piece with the rings going in the opposite direction. You want the rings to be as perpendicular to the board faces as practical. That's why we all covet quarter sawed lumber. Jim
 
#10 ·
Put the bow side up in the sun and watch it for a couple hours. You might get lucky.
...
Aren't you doing a floating top? IMO, 1" is a little thin for that type of top

- CWWoodworking
It started out as 6/4, and I hoped to finish with 5/4, but after all the milling I ended up with about 9/8. Thinner than I'd hoped, but it is what it is.
Try bringing it into the house for a few days. I store wood that I ll be making furniture with in the house because that s where it will end up. I only take it to the garage to work on.
...
Narrower boards glued up with bark side facing alternate directions helps keep things flat as well.

- whope
I brought it inside last night, hoping the stable temp and humidity will help it out :(
I've heard narrower boards are easier to keep flat, but the look of the wide boards is so pretty! This may be that hard lesson that makes me swear off wide boards. Although, at the moment, the board giving me the most grief is the narrowest one.
I ll leave them in the clamps till just before sanding and finishing. Sometimes there in there for a werk.

You can try the methods mentioned and you might also put them in the clamp in a reverse warp.

How wide were the boards glued together?

- JackDuren
I didn't think about leaving them clamped until sanding. Next time….
They range in width from about 5-12 inches.
Differential drying often causes that when you lay a glue up like like that on a bench overnight. In your picture you have it sitting on some stickers and that is usually enough to prevent that from happening. Storing it upright and leaning against the bench or a wall is usually better. A little heat on the convex side may flatten it back out but don t leave it in the sun too long or it could warp the other direction.

- Lazyman
I thought storing it standing up would be almost as bad as with a blocked face. In my limited experience, the wood I leave standing up gets awful twisted. This is something I really want to know.
Travis: You re not going to like this, but if your photo is representative of all the boards in your top, I think you should rip every board in the top in half and re-glue. I haven t seen a reply to the question "how wide are the boards?" but the photo you show makes me think they re are more than 6" wide. Unless you have some old growth lumber milled from BIG trees, you ll always have warping problems with boards that wide.
You need to interupt the growth rings, and glue each piece with the rings going in the opposite direction. You want the rings to be as perpendicular to the board faces as practical. That s why we all covet quarter sawed lumber. Jim

- Jim2020
You're right, I don't like hearing that! Honestly, I knew it would be a gamble using wide boards, I'd read many people who said never do it, and I read others who said it's okay. I took a chance because I like the look of wide boards. As I said above, the most problematic board right now is the narrowest one. I gave that board some extra attention with the belt sander because it was lifted up a little, and perhaps that opened enough grain that it re-lifted. But I expect if the wide boards do cause problems, it will manifest within the next few years.
 
#12 ·
It doesn't look that bad to me.
I arranged boards for the best look. If I lived somewhere near the Gulf of Mexico in a harsh climate I would do as jack suggests. Rip the boards narrow to get some of the fight out them and alternate the rings.
I live in very dry climate almost Between low desert and high desert.
Good Luck
 
#14 ·
It doesn't look that bad to me.
I arranged boards for the best look. If I lived somewhere near the Gulf of Mexico in a harsh climate I would do as jack suggests. Rip the boards narrow to get some of the fight out them and alternate the rings.
I live in very dry climate almost Between low desert and high desert.
Good Luck

- Aj2
Whew! The more I look at it, I think it will be okay as long as it doesn't experience shock transitioning from my garage to its new home inside my house.

I live in low desert, and it will be in my climate controlled house. Might experience some sunshine from a nearby window but otherwise will stay in 60-80 degrees and low humidity year round.

This is no problem at all, so long as you can snug it down to the frame when you assemble it.
I favor figure 8 fasteners, but there are many options to attach a top.

- pintodeluxe
It will sit on two cleats (trestle table). I am drilling 1/4 inch lag screws up through the cleats into the top (with some wiggle room in the cleats to allow for wood movement). 7 screws on each 36-inch cleat.
 
#15 ·
Tage Frid on alternating rings (from FWW #2 spring, 1976)

Another thing most books tell you is to alternate the wood to compensate for the cupping caused by shrinkage. This would be fine if you wanted to design a washboard. But if you want to use your wood, for example, for a tabletop, it will take a lot of screws to hold it down, plus every second board will usually have a lot of sapwood, especially today with the shortage and high cost of wood, where every piece must be used. But, if we don't alternate the wood, it will work together and form an arch that will be very easy to hold down with a few screws. Also, we will have the center of the wood facing up, meaning less sapwood, better color, harder and usually fewer knots.

Automotive lighting Automotive design Rectangle Handwriting Automotive exterior
 

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#16 ·
Tage Frid on alternating rings (from FWW #2 spring, 1976)

Another thing most books tell you is to alternate the wood to compensate for the cupping caused by shrinkage. This would be fine if you wanted to design a washboard. But if you want to use your wood, for example, for a tabletop, it will take a lot of screws to hold it down, plus every second board will usually have a lot of sapwood, especially today with the shortage and high cost of wood, where every piece must be used. But, if we don t alternate the wood, it will work together and form an arch that will be very easy to hold down with a few screws. Also, we will have the center of the wood facing up, meaning less sapwood, better color, harder and usually fewer knots.

Automotive lighting Automotive design Rectangle Handwriting Automotive exterior


- Rich
I've seen that (or something similar) before and so I just oriented my boards based on aesthetic. In double-checking the grain I see that there is no consistent pattern to my growth rings (a couple boards alternate, a couple boards match, etc.). Counting on everything just averaging out….
 

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#19 ·
Truly flat tabletops start with quarter sawn lumber, you can clearly see in your photos that is not the case, you can turn it upside down or have it under sunlight and it might straighten somewhat but eventually it will warp again, let it be and every once in a while use a large handplane and bring it back to flat. Nothing wrong with this, it is just wood behaving as such.
 
#20 ·
Tage Frid on alternating rings (from FWW #2 spring, 1976)

Another thing most books tell you is to alternate the wood to compensate for the cupping caused by shrinkage. This would be fine if you wanted to design a washboard. But if you want to use your wood, for example, for a tabletop, it will take a lot of screws to hold it down, plus every second board will usually have a lot of sapwood, especially today with the shortage and high cost of wood, where every piece must be used. But, if we don t alternate the wood, it will work together and form an arch that will be very easy to hold down with a few screws. Also, we will have the center of the wood facing up, meaning less sapwood, better color, harder and usually fewer knots.

Automotive lighting Automotive design Rectangle Handwriting Automotive exterior


- Rich

I ve seen that (or something similar) before and so I just oriented my boards based on aesthetic. In double-checking the grain I see that there is no consistent pattern to my growth rings (a couple boards alternate, a couple boards match, etc.). Counting on everything just averaging out….

- Travis
Those pictures are way more dramatic than need be…I worked for a 10 million dollar company making restaurant tables. Chilli ,outback, tilTed kilt,Ihop, etc. We along with Paxton and Liberty hardwoods all agree the wood must be alternated to get the most stability.

It was a lesson I learned and purchasing 10k a week in wood you have to get it right…

I didn't learn these things from books, I learned them from hands on knowledge..
 

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#24 ·
I've sat at tables in Restaurants that were built in production. They all have the same random look of grain going this way or that. That's exactly how a production should look.
When we makes a table for our house or friends house you can have harmony in the grain and still have everything lay flat.
Amateur woodworking verse commercial?
 
#25 ·
If I m having 100% quality results, I don t need to read a book to to understand why..

- JackDuren

Of course you don t. You re Jack Duren for Chrissake! But Jack, not everyone is as brilliant and knowledgeable as you are, and some input from a master and noted teacher may help them.

- Rich
Paul Sellers doesn't care what anyone else thinks and his 55 years of daily woodworking agrees with Tage. But he does give his theory on why quick production shops may chose to do it
https://paulsellers.com/2016/12/questions-answered-alternating-panel-sections-using-biscuitsdowels/
 
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