Fixing tabletop issues

[Eli Endres]

I just finished my first solid table top. It's air dried ash I milled from raw lumber. Moisture measured around 9%.

A local cabinet maker flattened the top with his wife belt sander. About a week after sanding when I applied finish I notice the top had bowed about 1/16 across it's 40" length.

Not a big deal.

It has now sat in my kitchen for 2 weeks waiting for the steel legs to arrive. I noticed last night that it had bowed further, closer to 3/8" at this point.

What are my options to flatten it? I've flipped it over and am going to let it sit for a few days to see if itll flatten back out some before I attach the legs. I don't expect it to actually move that much.

I need the table for thanks giving but I'm thinking in the spring I will try to repair this issue. Is my only option to slice the table up, replace and then reglue/refinish?

[Andrew Seemann]

A picture of the design would help with specific advice on what to do. In general, what you describe is not unusual, particularly for this time of year. Humidity is changing, and so will the shape of the wood. A solid wood table top will always move, even with a thick varnish on it. Some move less than others, due to species, finish type, grain orientation, and luck, but they will all move. It is just a property of wood. Fortunately ash tends to be a relatively well behaved wood.

Climate affects your local situation as well. I'm in MN, where we go from unbelievably hot and humid in the summer to unbelievably cold and dry in the winter. Wood movement is worse here than in most places.

I'm guessing that it isn't attached to aprons and legs, since you mention waiting for legs to arrive. Typically the apron serves to help keep the table flat. As long as you can draw it down when you attach it, it should be fine, assuming it is a well designed table. Any more advice would require seeing what it looks like

[Eli Endres]

Sadly my wife was opposed to an apron and wanted the top mounted directly on steel legs.

You are correct it isn't mounted. My plan was to draw down the 1/16" bow when I attached the legs however not that the bow is more extreme I'm worried about doing that.

[Richard Coers]

Usually caused by having in laying flat on a surface so air can't get to both sides, or finish was only applied to one side and moisture or humidity didn't get to both sides equally. Can also be caused by breadboard ends that didn't allow for movement.

[Eli Endres]

No breadboard ends bland it's finished both sides but it has been sitting on my ikea dining room table for the past week. That's why I have some hope that it will flatten a bit over the next few days since I flipped it.

http://imgur.com/a/cf9AGjG

[Jim Becker]

Block it up off the table surface it's living on currently so there is air flow on both sides. Hopefully when it was sanded, equal attention was paid to both sides to insure that moisture content was balanced.

[Jamie Buxton]

You can hide the aprons underneath the table, well out of sight of SHMBO. Your table looks to be at least six feet long, so you can put the aprons 10-12" from the table ends. Don't make them run the full 40" width of the table. Use maybe 32". You can also make the aprons 3" tall, and taper them up near the ends to be less obtrusive. Remember to use slotted holes in the aprons, or use figure-8 fasteners to allow the top to move across the grain.

[Eli Endres]

You can hide the aprons underneath the table, well out of sight of SHMBO. Your table looks to be at least six feet long, so you can put the aprons 10-12" from the table ends. Don't make them run the full 40" width of the table. Use maybe 32". You can also make the aprons 3" tall, and taper them up near the ends to be less obtrusive. Remember to use slotted holes in the aprons, or use figure-8 fasteners to allow the top to move across the grain.

That's a really good idea. Do you think I'll be able to pull it down flat with that or will I need to remill the boards?

[kent wardecke]

Awesome your self-made solid wood table sitting on the ikea table it will replace

[Jamie Buxton]

That's a really good idea. Do you think I'll be able to pull it down flat with that or will I need to remill the boards?

Yes, you should be able to pull 3/8" down flat. I don't think you need to re-make the top.

You can make the apron tall, in which case it will stay straight no matter what the top wants. Or you can make the apron not as tall, but make it curved, so both the apron and the top bend when you screw them together. How tall the apron needs to be, or how curved it wants to be, depends on how strongly curved the table top is. So you'll have to feel your way a bit.

[Jim Becker]

Along the same lines you can also use some steel C-channel to do the deed, ending far short of the edges as described above. it could even be put in a routed channel to make it less visible if you have enough thickness. And yes, you still need to use slotted holes to allow for seasonal wood movement. fixed position in the middle and any outboard fasteners in slotted holes through the metal or wood apron/cleats.

[Richard Coers]

Im curious where you live that a finished table top that measures 9% would cup that much. Do you have a good name brand moisture meter? How wide of boards did you use? If your wife doesn't want an apron, is she fine with the cup?

[Andrew Seemann]

That is a pretty table. For future reference, that piece of flat-sawn board in the center is likely a primary cause of your woe. It wants to cup and uncup with the seasons almost like a hinge. The other flat sawn piece two boards to the left with the growth rings in the opposite direction is trying to counter-act it though If you do another table in this style, try to put the quarter sawn pieces in the center and the flat on the ends. Or have aprons or breadboards, and then the grain orientation isn't much of a concern.

Sneak in some aprons or angle aluminum/steel ells or C's on this one and your life will be happier (and flatter)