Do you think this will stay flat using dominos

[lewisc]

Hi all,

I've got a student project (tv stand) that is using 5x30mm dominos to join the top and sides. The glued top doesn't sit flat unless clamped down.

It's got 4 5x30mm dominos along a 500mm length. Do you think the dominos combined with Titebond II will be enough to keep it in place?

 

[duburban]

you need to flatten the top first right? not on a jointer but at least like plane it so the boards are all the same thickness. does the school have a wide belt sander?

you could also add more dominoes to increase glue surface area

 

[lewisc]

We've got a drum sander that the panel won't fit on. He's been using a combo of belt sander, ETS 150/5 and scraping to get the panels flat. A bit more work is required on the top. The problem is that it still stick up even if the boards were the same thickness. I'll get him to add another domino on the end to increase the glue surface area.

 

[roblg3]

I would think that once clamped and glue has 24 set it will be just fine. I wonder if there was a technique issue when Mortising that created an upward tilt on that final board?  Has the side panel been checked for square? 

 

[Bohdan]

I think it will stay flat but the only risk is that the join in the top that is taking all of the load on flattening may let go with time as titebond is a thermoplastic glue that creeps.

 

[roblg3]

is it possible to flip the top over?

 

[Crox G]

I suggest that you add another domino nearer the front edge, then glue and clamp, and then pin the top part of the joint.  Drill into the end grain, well through the top of the tenon, say 5 mm above the joint and 30 mm deep.  Glue and drive in a dowel.  Those bamboo skewers have great shear strength if you can find a matching drill bit. Or you can find or make a dowel out of the original wood of the project.

Of course, this will change the look of the piece.  If you pin all the tenons going into the top, it may look like you planned it that way. 

The bottom part of the joint, with the long grain of the carcass side next to the long grain of the Domino, should be plenty strong without pin.  The failure will most likely be in the top part of the joint, where there is a small amount of the top's end grain glued to long grain of the Domino.

 

[sroxberg]

That appears to be solid wood, you might be able to glue it down but how is it going to expand and contract? Make sure you allow room for movement if it needs it. Not sure if it needs it but think about that now, not after it expands or shrinks and cracks.

 

[leakyroof]

Another way, if the student doesn't mind the hardware showing, is to use TableTop Buttons. You screw the figure eight metal 'button' onto the underside of the top and the side of the table. The ability of the button to pivot on the screws axis allows it to move with the Top if that wood section wants to go a bit with expansion or contraction, but, depending on how the button is installed, or which style is used, it keeps the top tight against the side for cosmetic purposes while still allowing wood movement.  Some work with a Kerf from a saw cut to install one end into, others are double screws[figure 8]
However, does that top still come off the Dominos right now, or is it mostly glued down already?  That could make using the Figure 8 style harder since easy installation would be affected.  Here is a Link to the 8's
http://www.rockler.com/desk-top-fasteners

 

[Svar]

It seems that the top is just warped, that usually does not produce much force. If you can push it down with bare hands that domino will hold it in place.
Wood expansion/contraction is irrelevant here. Both top and side have grain running in the same direction and will move together.

Having said that I don't like this kind of joint as tenon's flat side is facing end grain of the top and is too close to the edge.

 

[roblg3]

Pocket screw on the inside of the side into the top?

 

[lewisc]

Thanks for your replies. There's a few things you've said I hadn't thought off - especially the domino being glued to the end grain.

I've got some figure 8 fasteners and a few small angle brackets that could help support the top. It's at a point where he needs to get the project done. It's due in a week and he's panicking a bit.

Thanks for your suggestions.

 

[DzordanoBruno]

Take this wood wet with clean water, clamp it to flat surface and wait. Repeat this and wood copied flatness.

My english sucks ))

 

[Holmz]

Take this wood wet with clean water, clamp it to flat surface and wait. Repeat this and wood copied flatness.

My english sucks ))

[member=43782]DzordanoBruno[/member] your English is fine.
I was thinking more like "vapour water" (i.e. steam) and doing the same.

For a school project, that also makes sense as a learning experience.

Just I have no idea how long it needs to be steamed.

zbohom,
~Holmz

 

[Birdhunter]

I'd add a spline along the edge and pin it in both pieces of wood.