Need 2ft wide floating table, would joining two 12" boards be a bad idea? - Woodworking Talk - Woodworkers Forum
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post #1 of 18 Old 07-07-2019, 10:14 PM Thread Starter
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Need 2ft wide floating table, would joining two 12" boards be a bad idea?

This part of the project is 8' wide, 24" deep and 2" thick. It will also have a 24" deep, 6" high and 3/4" thick verticle hard maple strip every 18 inches across the boards in through dado.

I can get two sapele eight foot long 12" wide 8 quarter boards and then plane, joint them and glue up two of them for the size listed above but am worried that it will cup over time.

I've worked with sapele before and noticed on two 12 wide boards (only 1" thick though) that they had cupped after a few months sitting in the garage... so im wondering if the 2" thick boards will do the same. Im thinking the horizontal dados with maple might help keep them from cupping but not sure.

what do you guys think? Should i just rip them all to 6" inches and glue them up that way? would that even make a difference? any better ideas?

thank you
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post #2 of 18 Old 07-07-2019, 10:36 PM
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What is a "floating table?"


If those strips every 18" will be glued to the boards it is a bad idea. Remember wood movement.


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post #3 of 18 Old 07-07-2019, 10:46 PM Thread Starter
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What is a "floating table?"
It's a table thats attached to the wall with no feet touching the floor. I have heavy-duty L brackets that will go undermeath the table that will be secured to wall studs.

I see what you are saying about the glued strips providing problems with wood movement, didn't think of that. I was thinking of going with a tapered dovetail joint instead of a dado but thought it would be overkill and much tougher to get right. However, that joint doesn't need glue, if i remember correctly, and should account for movement.

thanks or pointing that out.


Maybe a set of breadboard ends would be best.... im trying to avoind cuppng, twisting, ect over the long term.

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post #4 of 18 Old 07-08-2019, 03:40 AM
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Why do boards cup?

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Originally Posted by Doc Fluty View Post
This part of the project is 8' wide, 24" deep and 2" thick. It will also have a 24" deep, 6" high and 3/4" thick verticle hard maple strip every 18 inches across the boards in through dado.

I can get two sapele eight foot long 12" wide 8 quarter boards and then plane, joint them and glue up two of them for the size listed above but am worried that it will cup over time.

I've worked with sapele before and noticed on two 12 wide boards (only 1" thick though) that they had cupped after a few months sitting in the garage... so im wondering if the 2" thick boards will do the same. Im thinking the horizontal dados with maple might help keep them from cupping but not sure.

what do you guys think? Should i just rip them all to 6" inches and glue them up that way? would that even make a difference? any better ideas?

thank you

Some boards cup, others do not. If you look at the ends of the boards you see that the cupped boards have long sweeping arcs of end grain, like dinner plates. As the wood dries out, the cells between the fibers shrink and the edges of the boards rise forming the cup. BUT on a board with vertical end grain, there is little of no cupping because there is not a differential rate of shrinkage. This is quartersawn wood and come when the saw mill blade is just at the correct place on the log to get vertical grain, OR the miller has selected that location on purpose. It is a wasteful process, but in the long run pays off due to lack of cupping issues.






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post #5 of 18 Old 07-08-2019, 07:44 AM
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The wider boards you use the greater the chances you will have for the top to cup warp. It doesn't necessarily mean that the two 12" wide boards you would use would cup. If that is the appearance you want I would go for it. Just however the top is made put a finish on the underside of the top. This will do more to prevent cup warpage than cutting the boards into smaller strips. As woodenthings posted, the closer you can get to quartersawn boards the better chances you will have.

Also working the project, never let the boards or the top lay on a flat surface. Warpage is generally caused by an imbalance in moisture content from one side to the other and laying the wood on a flat surface lets moisture from the air to only get to one side of the wood. At least put 3/4x3/4 strips of wood under a top when you leave a plank of wood on a bench for any length of time.
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post #6 of 18 Old 07-08-2019, 04:12 PM Thread Starter
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Thanks for the tips guys. It helps a lot. I will do what you say and post an update on the project once it's finished.
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post #7 of 18 Old 07-08-2019, 04:43 PM
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at 24" deep to the wall, think about a Plan B to the L-brackets.
depending on purpose yadda yadda - weight at 24" can create some serious 'pull out' forces at the studs.
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post #8 of 18 Old 07-08-2019, 06:34 PM
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Wait, you want a 2 foot floating span? I really hope that table is never going to see any weight near the end, thats a lot of leverage to put on any fastener, or even the brackets. Id be pretty worried about ripping screws out and the entire thing collapsing.

As far as the cupping goes, it depends. If the wood is well and properly dried and if its acclimated to your local climate and if you dont see temperature and humidity swings and if both sides are finished, it probably wont cup. Wood warps when moisture changes arent consistent across all the sides, like if one side was unfinished. Best answer that can be given is "maybe", theres too many variables to say for certain

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post #9 of 18 Old 07-08-2019, 08:22 PM
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Why wood cups!

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Originally Posted by epicfail48 View Post
As far as the cupping goes, it depends. If the wood is well and properly dried and if its acclimated to your local climate and if you dont see temperature and humidity swings and if both sides are finished, it probably wont cup. Wood warps when moisture changes arent consistent across all the sides, like if one side was unfinished. Best answer that can be given is "maybe", theres too many variables to say for certain

Not really.
It's actually about where in the tree/log the wood was cut from. As I said, a quartersawn board will not cup as much as a flat or plain sawn board just because the grain is vertical, not sweeping arcs:

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #10 of 18 Old 07-09-2019, 12:30 AM Thread Starter
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Wait, you want a 2 foot floating span? I really hope that table is never going to see any weight near the end, thats a lot of leverage to put on any fastener, or even the brackets. Id be pretty worried about ripping screws out and the entire thing collapsing.
yes, it will be against the wall extended out 24".

Here is an example of the idea.



I have 7 HD L brackets that also go out 24" that I plan on drilling into wall studs with drywall screws and then securing to the table top. I thought five to seven 24" long L brackets would support at least 200 lbs or so... I could be wrong.

Brackets are these https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

It says it supports 1000 lbs per pair... so i figure 4-5-6 (depends on the stud locations) of them should at least get me 200-300 lbs or so.

I really dont want it to collapse... cupping i can deal with... but if it falls then thats a big problem

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post #11 of 18 Old 07-09-2019, 02:51 AM
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Not really.
It's actually about where in the tree/log the wood was cut from. As I said, a quartersawn board will not cup as much as a flat or plain sawn board just because the grain is vertical, not sweeping arcs:
Why wood warps/cups, and how to stop it! - YouTube
Grain direction changes how wood warps, but the cause of the warp is still changes in moisture. If you were to seal perfectly season wood in a box with a perfectly consistent climate, the would would never move, cup or otherwise, no matter what the grain is like. I do agree that quartersawn is a better choice because its less likely to warp, but its not the catchall solution

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yes, it will be against the wall extended out 24".

Here is an example of the idea.



I have 7 HD L brackets that also go out 24" that I plan on drilling into wall studs with drywall screws and then securing to the table top. I thought five to seven 24" long L brackets would support at least 200 lbs or so... I could be wrong.

Brackets are these https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

It says it supports 1000 lbs per pair... so i figure 4-5-6 (depends on the stud locations) of them should at least get me 200-300 lbs or so.

I really dont want it to collapse... cupping i can deal with... but if it falls then thats a big problem
I wouldn't be worried about the brackets failing, I'd be worried about the fasteners. I'd ditch the drywall screws and use something a little heavier, like lag screws if you could manage. Honestly, I don't trust drywall screws. They're too easy to snap, makes sense for hanging drywall where youd rather snap off a head below the drywall, rather than stripping it, but not great for structural use.

Looking at the brackets you chose, it seems like a saner thing that a traditional floating design, but still, fastener choice is critical. Mount to studs with beefy fasteners. Same for the tabletop side of things, use the beefiest wood (not drywall) screws you can manage with your design. It may sound like I'm making a big deal over a little thing, but proper fastener choice can make or break a project. Its kinda like winter driving with all season tires, vs winter tires. Tiny thing with big effects

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post #12 of 18 Old 07-09-2019, 03:12 AM Thread Starter
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I wouldn't be worried about the brackets failing, I'd be worried about the fasteners. I'd ditch the drywall screws and use something a little heavier, like lag screws if you could manage.
you're right. it says on the amazon page to use lag bolts, 5/16" x 3", so I will . Thanks for the pointer!
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post #13 of 18 Old 07-09-2019, 04:13 AM
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Check out these other floating supports ...

There are better supports for a floating shelf/table than the ones you linked:
https://www.google.com/search?q=floa...#imgrc=_&vet=1


https://shelfology.com/shelf-hardwar...et-square-rod/


https://www.countertopbracket.com/Co...kaAqXkEALw_wcB


https://www.countertopbracket.com/pindex.asp

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 07-09-2019 at 04:25 AM.
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post #14 of 18 Old 07-09-2019, 05:43 PM
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Quote:
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you're right. it says on the amazon page to use lag bolts, 5/16" x 3", so I will . Thanks for the pointer!
No worries, fastener sizing is one thing you don't want to learn about the hard way... DAMHIK

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post #15 of 18 Old 07-11-2019, 02:47 PM
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In my humble opinion dry wall screws are for fastening dry wall, not for any other use, particularly anything that requires shear strength.

So yes, go with the lag bolts.

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post #16 of 18 Old 07-11-2019, 03:13 PM
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These kind of screws are replacing lag bolts in most construction applications. No predrilling, smaller diameters needed compared to lag bolts. You should be able to get them at local stores.

https://www.fleetfarm.com/detail/grk.../0000000247099




In woodworking there is always more then one way to accomplish something.
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post #17 of 18 Old 07-11-2019, 04:52 PM
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Quote:
Originally Posted by Terry Q View Post
These kind of screws are replacing lag bolts in most construction applications. No predrilling, smaller diameters needed compared to lag bolts. You should be able to get them at local stores.

https://www.fleetfarm.com/detail/grk.../0000000247099




In woodworking there is always more then one way to accomplish something.

Do they only come in #10 and 1/4in.? If so they would have limited usefulness.


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post #18 of 18 Old 07-11-2019, 05:50 PM
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I think those screws would be overkill. If there is sufficient blocking in the wall any wood screws or general purpose screws would hold a thousand pounds sitting on the table.
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