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Another Tabletop Question - Individual Boards Instead Of Glue-ups

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Forum topic by MrMan posted 02-09-2018 04:10 PM 1347 views 0 times favorited 12 replies Add to Favorites Watch
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MrMan

5 posts in 186 days


02-09-2018 04:10 PM

Hi all,

I’m aware of the fact that glue-ups react to RH along their width in the same way a single board does. To bypass this, I rip 1×4’s to square up the edges and then glue them INDIVIDUALLY (and not to each other) to the apron so they will expand and contract respectively.

Is this sound logic? Given that the boards are butted tight against one another, it doesn’t appear that there would be much room for movement so I’m confident I may be wrong.

Thanks!


12 replies so far

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Rich

3334 posts in 669 days


#1 posted 02-09-2018 04:35 PM

Nope, if they’re butted up against one another, it’ll still be a problem when moisture increases and they widen. When they dry and shrink, there will be gaps. If you’re OK with that, then why not shiplap them and leave maybe a sixteenth of an inch space between them (use something like pennies for spacers when you lay it out)? That can expand and contract without any problem at all. Just be sure not to glue them to the apron across their width. I’d suggest using battens to keep it all flat and put one screw up through the middle of each slat. A base sheet of plywood would do the same thing and add thickness and stiffness. There are all sorts of options.

You will likely have an issue with cupping, so seal it up well. We have a table out on the patio that my wife bought years ago that’s built with the shiplap slats mounted to a plywood base. It’s been through many monsoon seasons and is still solid. I did have to sand it flat several years ago because the slats had cupped, but I sealed it up and it’s still looking good.

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

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MrMan

5 posts in 186 days


#2 posted 02-09-2018 05:38 PM


Nope, if they re butted up against one another, it ll still be a problem when moisture increases and they widen. When they dry and shrink, there will be gaps.

That’s what I figured and was afraid of despite reducing width.


Just be sure not to glue them to the apron across their width.

As in don’t glue face grain to edge grain because it will inherently restrict movement? So just nails (not screws because of shearing issues)?

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MrMan

5 posts in 186 days


#3 posted 02-09-2018 05:38 PM

As in don’t glue the top to the apron as individual boards like in this picture?

https://woodgears.ca/joint_strength/spruce_testpiece.jpg

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Woodknack

12215 posts in 2460 days


#4 posted 02-09-2018 07:24 PM

Don’t glue the top to anything. I recommend you study how tables are built and/or copy an existing design. Furniture has evolved over centuries to be strong and allow for wood movement. I like books for learning because the authors are usually vetted. The Complete Woodworkers Companion by Roger Holmes is full of illustrations and photos and teaches the basics of furniture construction through a series of projects, I highly recommend it.

-- Rick M, http://thewoodknack.blogspot.com/

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bondogaposis

4889 posts in 2431 days


#5 posted 02-09-2018 07:49 PM

Is this sound logic? Given that the boards are butted tight against one another, it doesn’t appear that there would be much room for movement so I’m confident I may be wrong.

No, that is not sound logic and you are dead wrong. Glue them up and attach them to the apron in such a way that the panel can move. There several methods to accomplish this,the most common being buttons or z clips.

-- Bondo Gaposis

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bobro

320 posts in 1390 days


#6 posted 02-09-2018 07:58 PM



As in don t glue the top to the apron as individual boards like in this picture?

https://woodgears.ca/joint_strength/spruce_testpiece.jpg

- MrMan

There is a simple technical term for that “joint”, it is called “wrong!”.

-- Lao Ma: You are so full of anger and hatred. Xena: Everybody's gotta be full of something.

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MrMan

5 posts in 186 days


#7 posted 02-09-2018 08:53 PM

Right. I’m aware of the need to attach full glue-up panels to the apron using Z clips or buttons but I was just wondering if I could get away with attaching individual boards <= 3” in width directly to the apron using brads and titebond. Thank you for clarifying.

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bonesbr549

1569 posts in 3147 days


#8 posted 02-09-2018 09:10 PM

Ok, not going to pile on, but you gonna have problems. When doing a top, go solid, but allow it to move laterally and there is no way to get around it. Many ways to attach to apron. I’ve used lazy 8’s and I’ve used elongated holes in the apron and screwed into top to hold it down. If you go solid end, breadboards.

Many a book on wood movement, and youtube vids. If its bound cross grain, it will pop or shrink and expose a gap.

-- Sooner or later Liberals run out of other people's money.

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MrMan

5 posts in 186 days


#9 posted 02-09-2018 10:34 PM

Thanks again. Another quick question. Given that plywood is much more stable than solid wood, is it appropriate to glue and/or screw a plywood top to an apron or do the same principles apply?

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Rich

3334 posts in 669 days


#10 posted 02-09-2018 11:13 PM


Thanks again. Another quick question. Given that plywood is much more stable than solid wood, is it appropriate to glue and/or screw a plywood top to an apron or do the same principles apply?

- MrMan

You can attach plywood directly to the aprons. Long grain to plywood is OK, but if you glue boards down to it flat, you’ll have trouble. Lots of ways to get around that though.

You’re getting a lot of advice about how you must do a solid glue up and attach it this way or that. I stand my my first post that if you want to use narrow 1-by boards, shiplap them and leave a bit of space between each for movement, and don’t attach them across their width, do it at just one point. That’s the way lots of older furniture had floors and backs constructed. Drawer bottoms too. Anytime they had to allow for movement in a confined space, that was a common technique. They didn’t have plywood, and needed to allow for movement.

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

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Aj2

1576 posts in 1878 days


#11 posted 02-09-2018 11:43 PM



Hi all,

I m aware of the fact that glue-ups react to RH along their width in the same way a single board does. To bypass this, I rip 1×4 s to square up the edges and then glue them INDIVIDUALLY (and not to each other) to the apron .

- MrMan

I’ve never heard anyone say something like this. What does it mean?
Maybe just look up figure eight fasteners for a table top too see how to properly build your table.

-- Aj

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gargey

1013 posts in 855 days


#12 posted 02-09-2018 11:47 PM

wood movement is a pain the ass. there is no way to short-circuit it, you have to accomodate it.

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