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Trouble with table bowing

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Forum topic by Rwndy posted 06-19-2019 02:22 PM 547 views 0 times favorited 27 replies Add to Favorites Watch
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Rwndy

11 posts in 35 days


06-19-2019 02:22 PM

Topic tags/keywords: woodworking table

Hey everyone, I’m new and I’ve just built my first dining table 70” long , the wood I used has been in the barn for about 4 years stacked with sticks between every layer, I brought it in the shop and let it take 2 weeks between planing and the time I started glueing . I glued the top into 2 pieces making sure I clamped straight edges on to keep them straight, and then put the 2 half’s on the frame and clamped and glued them together with straight edge clamped to them , after another week in the shop putting tongue oil finish on I took the table in the house , after sitting in the house for a week this table got a bow in the top , I rushed it back to the shop and put tow straps on the legs and pulled it back in over a couple of days , My question is , will this table bow again when I take the straps off ? Help . Lol


27 replies so far

View Steve's profile

Steve

1360 posts in 1004 days


#1 posted 06-19-2019 02:36 PM

Did you put finish on both sides of the table?

Any pics of the bow?

View SMP's profile (online now)

SMP

1199 posts in 328 days


#2 posted 06-19-2019 04:53 PM



Did you put finish on both sides of the table?

- Steve

Was going to ask this, and same number of coats

View AEVilleneuve's profile

AEVilleneuve

14 posts in 36 days


#3 posted 06-19-2019 05:00 PM



Did you put finish on both sides of the table?

Any pics of the bow?

- Steve

Funny enough, this was published today:
https://www.popularwoodworking.com/editors-blog/finishing-both-sides-does-not-prevent-warping/
(I don’t have the experience to have a strong opinion on this)

But it could also be that the top wasn’t glued up with alternating grain directions to minimize the effect of the movement.

View Firewood's profile

Firewood

849 posts in 2056 days


#4 posted 06-19-2019 05:26 PM

Welcome to LumberJocks. Your profile doesn’t show where your located or anything about your shop, but it sounds like your home has quite a different RH than your shop. In my experience, air dried wood doesn’t seem to be as stable as kiln dried. If your shop isn’t conditioned like your house, then then it’s unlikely the MC of the wood changed much from being in the barn – until you moved it into the house.

If you can get it to flatten out again in the shop, I think the best advise is to make sure all surfaces are equally sealed so that as the wood looses moisture in the house, it does it as evenly and slowly as possible. Good luck.

-- Mike - Waukesha, WI

View Aj2's profile

Aj2

2321 posts in 2220 days


#5 posted 06-19-2019 05:30 PM

Alternating grain direction is hocus pocus. Always glue up table top for the best look. I have found table tops will warp for lots of different reasons and for no reason that we can predict.
For me I’ve learned how to pick boards that are somewhat predictable. When and how I handle them is important for success.
Always arrange the boards for harmony or the table not worth making.
Good Luck

-- Aj

View Rich's profile

Rich

4575 posts in 1011 days


#6 posted 06-19-2019 06:15 PM

I haven’t posted this for a while, but since the alternating grain fallacy was mentioned, time to put it back out there.

Tage Frid on Alternating Rings

“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.”

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

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Monty151

69 posts in 263 days


#7 posted 06-19-2019 06:32 PM

^ That right there is how all my tops are glued up.^

View Aj2's profile

Aj2

2321 posts in 2220 days


#8 posted 06-19-2019 07:13 PM

Here’s my tip for anyone interested. Looking at the end of a board or Rich’s picture see the curved growth rings.
Many times this is how a board will cup because the growth rings are trying to flatten out. Or become straight
Not always but it’s a good bet.
Good Luck everyone

-- Aj

View JohnMcClure's profile

JohnMcClure

634 posts in 1062 days


#9 posted 06-19-2019 07:41 PM

Rich,
Thanks for posting that. I’ve seen a lot of (heated) arguments back an forth on the subject, but that was concise and makes a TON of sense to me in a way it never did before. Now I feel like, DUH – if the bow is in one direction it’s easy to straighten; and if it’s up in the center, even better – you can pull it down with a screw! I’m going to try and remember this when it’s my turn to build a dining table.

RWNDY, good luck – I have no advice for you, and it’s a bit late for you to align your boards – but please post back again to let us know what worked, if anything! And post your table as a project!

-- I'd rather be a hammer than a nail

View Rich's profile

Rich

4575 posts in 1011 days


#10 posted 06-19-2019 07:45 PM

I should have noted that the Tage Frid quote was taken from an article he wrote in Fine Woodworking Issue #2 in Spring 1976.

Back to the OP (although as so often happens here, he hasn’t followed up on the thread with more information). I would recommend attaching some battens to the bottom of the table to pull the bow out. Be sure to allow for wood movement, etc.

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

View sras's profile

sras

5115 posts in 3551 days


#11 posted 06-20-2019 05:09 PM

How is the top attached to the apron? Is it glued?

-- Steve - Impatience is Expensive

View tywalt's profile

tywalt

58 posts in 586 days


#12 posted 06-20-2019 05:32 PM

I second Steve’s question above. Need some more info on the construction (or some pics) to help you out with some probable solutions. Also, what kind of wood?

My preferred method to prevent table top movement is the old tried and true bread board ends. Not sure if you have any more of the same wood left over, but it should be a relatively simple process to add some bread boards to your existing top… ask me how i know ;). There are a couple ways to approach that but again, would like to know more before I chime in with anything specific.

-- Tyler - Central TX

View Rwndy's profile

Rwndy

11 posts in 35 days


#13 posted 06-20-2019 06:03 PM


Did you put finish on both sides of the table?

Any pics of the bow?

- Steve


Did you put finish on both sides of the table?

Any pics of the bow?

- Steve


View Rwndy's profile

Rwndy

11 posts in 35 days


#14 posted 06-20-2019 06:14 PM



Did you put finish on both sides of the table?

Any pics of the bow?

- Steve

Did you put finish on both sides of the table?

Any pics of the bow?

- Steve
I have no pics of the bow , I glued the top all the way around the frame and it has one crossmember in the middle and I glued it too , the bow was in the middle, I put tongue oil coats all the same coats top and bottom and frame and legs , I took it back to the shop and was able to pull the bow out and put 4 coats of laquer finish on top, can I take the table inside the house and leave straps on the legs for a week or 2 or do I need to put extra supports you were talking about but I need more info on what you was saying , I put 1 cross support in the middle

- Rwndy


Did you put finish on both sides of the table?

Any pics of the bow?

- Steve

Did you put finish on both sides of the table?

Any pics of the bow?

- Steve

- Rwndy


View therealSteveN's profile

therealSteveN

3116 posts in 996 days


#15 posted 06-20-2019 06:31 PM

- Steve
I have no pics of the bow , I glued the top all the way around the frame and it has one crossmember in the middle and I glued it too , the bow was in the middle, I put tongue oil coats all the same coats top and bottom and frame and legs , I took it back to the shop and was able to pull the bow out and put 4 coats of laquer finish on top, can I take the table inside the house and leave straps on the legs for a week or 2 or do I need to put extra supports you were talking about but I need more info on what you was saying , I put 1 cross support in the middle

- Rwndy

- Rwndy

You don’t say the WIDTH of the top. If the grain was running long, IOW with your 70” length, then any, and all shrinkage, and movement will be across width of the top. You don’t mention your location, but it is 75 to 90* here right now, and pretty humid with almost daily rain. A project here made out in an unconditioned place, and brought into a nice air conditioned home could conceivably have movement on the first day.

Your use of glue to NOT allow that top to move as it will want to do, is likely your cupping issue, and it will only get worse going into a winter.

Proper installation if a top of any size, especially one of the length, and maybe the width you could have here requires the use of fixation devices to secure the top, but ALSO allow it to move seasonally.

Watch this video

Woodworking is all about learning. From the looks of your frame it is done well. Likely you will learn one of the most valuable lessons here. Wood moves, you need to allow for it. It never gets longer, it sure does get wider though. Depending on width and species of wood, thickness, and varied degrees of temp, and humidity it can be a lot, or just enough to cause trouble, but it moves. FWIW if you polled everyone here, probably a lot of them have done what you did. About half of most woodworking videos are shots of people smearing glue all over everything…......

-- Think safe, be safe

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