UGH! Wood does strange things

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Forum topic by cracknpop posted 01-14-2017 12:30 PM 1088 views 0 times favorited 19 replies Add to Favorites Watch
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333 posts in 2527 days

01-14-2017 12:30 PM

Topic tags/keywords: oak cupped

Wife asked me to build our daughter a TV stand/entertainment center the week before Christmas. Finished it minus doors and drawers to give it to her on Christmas Day. Carried it in from my heated shop and it sat in the house for a week then back to the shop for the doors/drawers. Went to the shop a week later and heater had quit, it was 40 degrees (6 degrees outside). Noticed the top had cupped 3/32” in the 17 1/2” from front to back??
-red oak, kiln dried, had been in my garage nearly a year
-top was made with 4-5” wide boards jointed to flatten before planing
-alternated grain during glue up, glued 2 boards at a time
-drum sander to smooth after glue up
-stained, sealed, lacquered both sides
-attached with figure 8 desktop fasteners

UGH!!!! Off to the shop to make a new top

-- Rick - I know I am not perfect, but I will keep pressing on toward the goal of becoming all I am called to be.

19 replies so far

View Monte Pittman's profile

Monte Pittman

29976 posts in 2516 days

#1 posted 01-14-2017 12:53 PM

Wood can be merciless. Temperature, humidity are huge.

-- Nature created it, I just assemble it.

View BB1's profile


1195 posts in 1026 days

#2 posted 01-14-2017 12:55 PM

I’m too new to woodworking to offer any helpful comments. Was the wood cupped at all originally before it was jointed and sanded? Interested in hearing from others possible reasons why this happened as it seems like you took so many steps to avoid the issue. Sorry you are having to redo the top -looks like a really beautiful project.

View UncannyValleyWoods's profile


542 posts in 2042 days

#3 posted 01-14-2017 01:57 PM

Just curious, how long did you allow your glue up to remain clamped / how long did you let it chill out and sit around before you attached it to the top and finished construction? I learned from a guitar maker friend that often, when doing laminated pieces, it is often good to do your glue up, then let the piece sit unmolested for weeks, months, or years. He specifically does this with guitar necks. He’ll glue up one neck ever few days, but he builds from necks he glued up over a year ago (I understand that isn’t practical for your project). He’s got it worked out so that he always has a neck to build with, but each neck has had plenty of time in its laminated state to “come to rest”... I’ve done this with several table tops. I don’t let them sit a year, but I will let them sit a month or so. I’ve got eight quarter sawn oak legs that will eventually be the legs to a couple of Greene and Greene style side tables, and I glued them up six months ago and likely will not build with them for another six months.

-- “If Jesus had been killed twenty years ago, Catholic school children would be wearing little electric chairs around their necks instead of crosses.” ― Lenny Bruce

View dhazelton's profile


2789 posts in 2475 days

#4 posted 01-14-2017 02:19 PM

If your eye can’t pick it up without putting a ruler to it I would leave it alone. The TV won’t tip over and you probably can’t feel it when you run your hand over it. I know you want perfection but it’s attractive and functional as it is.

View Rich's profile


3769 posts in 767 days

#5 posted 01-14-2017 03:14 PM

I’m with dhazelton. It doesn’t look extreme enough to matter. 3/32 inch over 17-1/2 is not going to be noticeable, unless you fall victim to the compulsion to point it out to everyone who admires it (like we all tend to do with the imperfections in our work).

Keep in mind, it may fix itself as it stabilizes. I’d at least wait and see what happens.

Nice piece, BTW. That looks like really nice workmanship and finishing.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View LittleShaver's profile


411 posts in 797 days

#6 posted 01-14-2017 04:41 PM

Leave it where it is for 6-12 months and see what happens. You can always build another top for next Christmas if it gets worse or doesn’t perform the way it should.

-- Sawdust Maker

View BurlyBob's profile


5937 posts in 2444 days

#7 posted 01-14-2017 05:34 PM

I agree leave it alone. That’s not a really big cup.

View bbasiaga's profile


1240 posts in 2173 days

#8 posted 01-14-2017 07:46 PM

Yeah, just leave it. You’ll make a new top, and some months or years later that one will take a new shape too. Flat = flat enough for its intended purpose.


-- Part of engineering is to know when to put your calculator down and pick up your tools.

View Madmark2's profile


392 posts in 766 days

#9 posted 01-14-2017 10:13 PM

Wood was a living thing. It will do what it wants no matter what. Tops want to cup as the top surface has more air flow than the bottom.


View htl's profile


4202 posts in 1337 days

#10 posted 01-14-2017 10:31 PM

Put a bowl a flowers on top of it and no one will notice.

-- An Index Of My Model making Blogs

View ScottM's profile


689 posts in 2325 days

#11 posted 01-14-2017 10:32 PM

Leave it alone!!

View EEngineer's profile


1116 posts in 3791 days

#12 posted 01-15-2017 12:10 AM

This is why I laugh when people talk about cutting wood to .001”. Are you nuts?

-- "Find out what you cannot do and then go do it!"

View Kelly's profile


2106 posts in 3122 days

#13 posted 01-15-2017 12:43 AM

This is why I’m a fan of ignoring even “pro’s” and “experts” and treating the insides of chest and things. It is interesting we will prime and paint all sides of a board before putting it on the side of our house, but not do the same on a pieces of fine furniture.

One might say not finishing the inside of a dresser is a bit like the story of the little girl asking mom why she cut the ends off the ham before roasting it. Her mom told her she learned it from her mom, so to go ask grandma. Grandma said it was simple – it wouldn’t fit in the pan.

In truth, the main reason the interiors of dressers and things were not and are not done is, time and money. I prefer to make it more likely I can move a pieces between London and Death Valley without damaging the furniture.

View Mainiac Matt 's profile

Mainiac Matt

8516 posts in 2507 days

#14 posted 01-15-2017 01:04 AM

How thick were the boards before you joined them flat and planed them? It looks like most of you cup is coming from one board just forward of the middle. I wonder if that board had some internal stress locked in that was relieved by planing down the thickness and then found it’s new “happy medium” a week later.

I agree that it is not bad enough to replace. Get it set up at your daughters place and then monitor it over a couple season changes and see what happens. It may flatten out come summer humidity.

-- I yam what I yam and that's all what I yam

View robscastle's profile


5389 posts in 2382 days

#15 posted 01-15-2017 01:10 AM

Cut some stress relief grooves in the under side or as indicated above in a couple of instances LIA,

-- Regards Rob

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