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Warping on a tabletop

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Forum topic by Leviticus posted 754 days ago 950 views 0 times favorited 12 replies Add to Favorites Watch
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Leviticus

3 posts in 754 days


754 days ago

Hate that this is going to by my first post here, but:

My sister brought me an old card catalog that she rescued from a barn in South Carolina. The drawers were in decent shape, but the carcass was a loss (except for some internal dividing members that I re-used.) She said: Do with it what you will, but I could really use some night stands.

I did some math, and a lot of rough sketches and decided how to distribute the drawers, etc. I was REALLY proud of this project – one of my first ‘furniture’ builds. So much so that I decided that I’d make hardwood tabletops for it. I ran over to the hardwood yard and got some 4/4 hard maple. It comes S2S, so I jointed it on my table saw using this style jig. It did a fairly decent job for the stock blade and a 5-minute jig build.

Well, I finally finished the tables and took them to my sister at a family gathering, where they sat in a hot car for several hours – the affects of this didn’t occur to me until my sister sent me some pictures when she got home:

photo (7)

photo (6)

(Sorry for the quality, they’re cell phone pics – I’ll update once she brings the tables back.)

Obviously, they are cupped quite badly, and one even started to split at the joint.

I’m not sure if they’ve improved after sitting in her home for a week now, but I doubt it.

The tops are screwed on through the top of the main case, in 4 points: 2 in the back, 2 in the front, on either side of the center divider.

I’m curious how much the heat/humidity did this, how I might be able to repair it (I’m prepared to just re-create the surfaces all together at this point), and what I might do differently in the future.

Thanks for any input!


12 replies so far

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Lee Barker

2163 posts in 1448 days


#1 posted 754 days ago

Nice work! I like the righteousness of reclaiming the drawers and combining them with your own skill. This is a neat project all the way around.

My input: The warm car probably hurried along the inevitable: moisture in the wood. If you had a jointer and a planer, you could split the tops on the glue line and surface them flat and reglue them and they’d be fine, but thinner to an obvious degree.

Starting over would be my suggestion. I would overbore the holes in the carcase and screw them down three in front and three in back.

OR:

Typically on a piece of these proportions, the grain runs side to side, not front to back. If you do that, the glue line is not readily visible. And your overhang, on the sides, will be equal to or a little bit greater than the front, which should extend to the approximate projection of the hardware.

If you did this, then your 3 screws would be on the sides, not the front and back.

And they’d live happily ever after.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

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killerb

150 posts in 996 days


#2 posted 754 days ago

Are the tops grain running in the same direction as the case sides? You have end grain showing on the front and they should be going sideways. Slot for your screws. Yes the heat did not help. Did you finish both the top and bottom of the tops? Your butt joints were not good enough . You see the pieces coming apart at the glue seam? Do you have a hand plane and is it sharp? WE can get you through this, but you need to start over, I hate to say. Nothing to be mad at, its just learning. WE all have been there. bob

-- Bob www.bobkloes.com

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Leviticus

3 posts in 754 days


#3 posted 754 days ago

So, this is the result of moisture moving into the wood, or out of? Pardon my ignorance.

I know that a jointer and planer are in my future, and I’m trying very hard not to make this situation a justification to just run out and by them! LOL

My reason for the grain direction was mostly aesthetic – the drawers, thereby the table is quite long, and the maple had some great grain in it I wanted to show off.

I had only put the four screw in to allow for expansion, but if I overbore enough, can I use the screws to keep the table flat and prevent this again?

I did a sketch of the screw locations:

table top

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Leviticus

3 posts in 754 days


#4 posted 754 days ago

Thanks Lee, Bob – actually, the piece is completely unfinished at this point; now that I think about that, maybe finish would have helped prevent this.

Yeah, the joints were basically ‘just good enough’, as they were made with a table saw. The joint failure isn’t a shock at all, and I’ve come to terms with that, LOL – it’s that amount of cupping and the proper attachment method for this situation that I’m really hung up on.

I did overbore the 4 holes that are in it – I’ll turn them into slots on the rebuild.

Anybody in Atlanta got a jointer and planer they wanna let go for cheap? ;)

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a1Jim

111999 posts in 2175 days


#5 posted 754 days ago

It may be the wood was not dry enough in the first place ,but you never screw a table top down solid you can have enlarged holes or use some hardware called figure 8s or even put a groove around the edge to make little tabs that allow the wood to move as it wants to do. Before you start over wit new wood I wood saw the top apart at the original joint and then saw the two halve in half and glue it all back together. Becareful when sawing wood with cups in it,it’s best to have the concave part of the cup facing up. you will have to cut the pieces again to be able to get the top to glue back together flat so you have to take as little of the boards so that your top is not to short.

http://lumberjocks.com/topics/38368
http://www.leevalley.com/us/hardware/page.aspx?c=&p=50311&cat=3,41306,41312

-- http://artisticwoodstudio.com Custom furniture

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GMman

3902 posts in 2295 days


#6 posted 754 days ago

Lee and Bob gave you very good advis..
I had the same thing happen to me I heat with wood and sometime it gets very hot and my lumber was not dry enough.
It’s an easy fix or make new tops.
I got me a moisture meter that is someting that is good to have.

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ChuckV

2378 posts in 2125 days


#7 posted 754 days ago

Jim,

it’s best to have the concave part of the cup facing up.

Maybe I’m misunderstanding. It seems like the piece would be more stable with the concave side down on the table. That way, the two outside edges will support the piece.

-- “That it will never come again / Is what makes life so sweet. ” ― Emily Dickinson

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a1Jim

111999 posts in 2175 days


#8 posted 754 days ago

Chuck
If you put the convex side up the wood falls when you finish the cut and pinches the blade throwing the wood at you. you do have to hold one side down when cutting concave up.

-- http://artisticwoodstudio.com Custom furniture

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ChuckV

2378 posts in 2125 days


#9 posted 754 days ago

Jim,
Thanks for the explanation. I’ve never ripped a cupped piece down the center like that on a table saw.

- Chuck

-- “That it will never come again / Is what makes life so sweet. ” ― Emily Dickinson

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Grandpa

3046 posts in 1273 days


#10 posted 754 days ago

Attach the tops like A1Jim suggested. I have done most of the things that were wrong at some point in my life and he is telling you how the craftsmen did it for years and years. Little clips hold a table top in place. They float. I think a combination of heat and moisture got the best of you. I have seen people leave raw boards in the sunshine and the results were worse than what you are showing. Looked more like potato chips.

View Lee Barker's profile

Lee Barker

2163 posts in 1448 days


#11 posted 754 days ago

Good discussion all the way ‘round. I’d just add that finish would not have prevented this. It was as inevitable as remembering how to ride a bicycle.

I truly don’t know where that simile came from.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

View Rick M.'s profile

Rick M.

3777 posts in 978 days


#12 posted 754 days ago

If the sun shone on the top it would dry the top faster than the bottom causing the cupping you see; or it could just be general heat/humidity. Finish the wood next time before hauling it anywhere to help prevent moisture loss/gain.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

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