# How to keep table tops from bowing!



## eschatz (Feb 12, 2014)

I've alternated growth rings (which I've heard isn't really a thing). I plane and then joint. For an 18" end table top I put two pipe clamps on the bottom and one on the top in the middle. 

The tops come out flat but then within a day they bow up. My sawyer kiln dries his wood and has it in a barn that is essentially the same environment as my garage. I get it about 15 miles away. I wouldn't think that I need to let it "acclimate" to my garage when it's been in the same humidity really. 

I don't have a moisture meter. When I cut sides for tables and things they don't do this. Only tops and only after they're glued.


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## eschatz (Feb 12, 2014)

I've done a pocket joint to hold them together and I've also done butt joints (which I think is fine for most tops).


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## woodnthings (Jan 24, 2009)

*they may be the same moisture content ...*

Let's assume that they are. Then if you have planed them equal amounts off both surfaces all should be equalized.
If they look like saucers on the ends rather than vertical lines, that's a reason they will cup or bow also. 

A 3 board glue up will stress the center board a little more than the outer ones, so flipping the center one to opposite grain direction should help. 

Finally, let the boards acclimate to your garage shop about 2 weeks and see if that improves the issue. I use outside air dried lumber, but it's been in the shop for months before milling, planing etc. and I have no issues that way.


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## eschatz (Feb 12, 2014)

woodnthings said:


> Let's assume that they are. Then if you have planed them equal amounts off both surfaces all should be equalized.
> If they look like saucers on the ends rather than vertical lines, that's a reason they will cup or bow also.
> 
> A 3 board glue up will stress the center board a little more than the outer ones, so flipping the center one to opposite grain direction should help.
> ...



I usually joint one side and then plane the other side to meet my thickness. So I'm guilty there. I understand the cup wanting to expand thing. However, I usually hand plane the top and I need all of the grains running the same way to make it work. I assumed that I wanted the grain running all the same direction for no tearout when I hit it with my smoothing plane. Do you think I should get a moisture reader?

Thanks for the reply. I know this is some basic woodworking but seeing 30 people look at the thread and nobody make a comment was kind of defeating.


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## Tennessee Tim (Dec 15, 2010)

Eschatz,
First .....on Sundays the volume is usually a lot smaller on replies then other days of the week and second ....some threads go for a few days before replies are posted.

Now to your issue.....
1st) I see a common drying issue that dryers AND buyers do....They kiln dry the lumber to moisture % numbers desired and then they store it (as in your case) in a barn or uncontrolled MC room....THAT produces Hades on lumber. YES I'd advise a MC reader/tester.
2nd) show us some end pics of the tops with a straight edge layed across so we can give you a better judgement.
3rd) How soon are you mounting the tops??? Same day,,,week,,,month. What is your mounting proceedure? glued, screwed, clips, oblong holes???? 
4th) How soon are you finishing??? Are you finishing both the top and the bottom sides????
5th) Swapping end grain cups is a large arguement here. I personnally used to argue it made a difference until I realized it had more to do with proper drying and mounting techniques.

Please post the pics for better answers.


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