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The right screw to attach table top?

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Forum topic by Marshall posted 12-15-2014 05:30 PM 2852 views 0 times favorited 14 replies Add to Favorites Watch
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Marshall

151 posts in 1515 days


12-15-2014 05:30 PM

Hello all,

I’m working on a walnut slab table with a nakashima inspired base.

My plan to attach the top to the base is to route slots in the supports and drive wood screws into the top. I’m thinking three screws per support (one at center and one at each end). I have a few quesitons:

1. What is the best screw for the job? McMaster has this: http://www.mcmaster.com/#98643a640/=v1awvs
I was thinking I could use these with washers?

2. Is three screws per support enough?

3. The center screw would drive through the glue joint. Is that ok?

4. How long does the slot need to be? I was thinking 1”. The table is 42” wide made from two slabs of walnut.

Thanks in advance for the advice!

-- Marshall - http://mcomisar.tumblr.com


14 replies so far

View a1Jim's profile

a1Jim

115201 posts in 3037 days


#1 posted 12-15-2014 06:02 PM

Hi Marshall
You might consider using figure 8s to attach your top,this will allow for wood movement.

http://www.superiorhardwaresupply.com/fasteners.aspx

-- http://artisticwoodstudio.com Custom furniture

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Marshall

151 posts in 1515 days


#2 posted 12-16-2014 03:08 PM

Thanks Jim, these look interesting.

I’m not clear how these allow movement. I see that they pivot about the center screw, but then the screw in the table top would move radially, not laterally across the grain? It seems like this would still be restrictive? Thoughts?

Do you think these will work for my 42” wide walnut table top? Looking around on the internet, it sounds like I can expect somewhere between 1/2” – 1” of expansion.

Thanks

-- Marshall - http://mcomisar.tumblr.com

View waho6o9's profile

waho6o9

7166 posts in 2037 days


#3 posted 12-16-2014 03:49 PM

Spax or GRKs work well for fasteners.

Here’s some GRKs:

View a1Jim's profile

a1Jim

115201 posts in 3037 days


#4 posted 12-16-2014 03:59 PM

Marshall
I use these Figure 8s all the time, they’re one of a few ways to allow for wood movement. you drill a shallow hole in you cross members just the thickness of the fig8 at perhaps 4 locations for a 42” wide table,then screw the fig 8s down but you leave them loose enough to turn. you then screw them to the top of the table,they then swivel when the table top expands or contracts across the grain. You still will have one more issue to address re wood movement,it’s your center cleat . You can attach it with screws but you need to elongate the holes in the cleat to allow the screws to move with wood movement.

-- http://artisticwoodstudio.com Custom furniture

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a1Jim

115201 posts in 3037 days


#5 posted 12-16-2014 04:18 PM

waho609 must have been typing the same time I was,his photo shows all of the best techniques for attaching a table top,but for your application I feel the fig8s would still work best. For a table with an apron any of the connectors in the photo work great .

Here’s a great article about wood movment

http://toddpartridgedesign.com/sr_pages/documents/UnderstandingWoodMovement.pdf

-- http://artisticwoodstudio.com Custom furniture

View Marshall's profile

Marshall

151 posts in 1515 days


#6 posted 12-16-2014 04:24 PM

Thanks both of you for the advice! I’m going to use those “Z fasteners” for another table I’m working on that has an apron.

I made some wooden tongue and groove fasteners like the ones pictured for an old TV Stand project. I had a number of them split when I drove the screw. I dont know if i just didnt make them wide enough or what. I like the pre-made metal ones – less work for me :)

-- Marshall - http://mcomisar.tumblr.com

View BinghamtonEd's profile

BinghamtonEd

2281 posts in 1829 days


#7 posted 12-16-2014 04:29 PM

I think the approach you mentioned in your original post would work. You said this is made from 2 slabs of walnut, are they joined together, or separate? If they’re joined into one slab, you could do a normal hole in the center of each cross piece, and elongated holes on each end of the supports. If they’re separate, you may want to do two screws in the center of the support (one into each slab), and then elongated holes on each end.

I’ve only done this twice, both times were cleats for chest lids. Both times, I did elongated holes and used oval-head screws so that the underside of the screw head sat flush with the cleat.

-- - The mightiest oak in the forest is just a little nut that held its ground.

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BinghamtonEd

2281 posts in 1829 days


#8 posted 12-16-2014 04:32 PM


I made some wooden tongue and groove fasteners like the ones pictured for an old TV Stand project. I had a number of them split when I drove the screw.
- Marshall

Are you talking about fasteners like this :

If so, it sounds like you didn’t pre-drill the hole in the fastener large enough. The screw threads don’t need to engage in the small fastener, just the top it’s attached to (it’ll pull the fastener tight as you drive the screw in).

-- - The mightiest oak in the forest is just a little nut that held its ground.

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Marshall

151 posts in 1515 days


#9 posted 12-16-2014 04:32 PM

Thanks Ed. The slabs are glued.

Yeah, that was probably the problem. I pre drilled it, but the threads still engaged.

-- Marshall - http://mcomisar.tumblr.com

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Marshall

151 posts in 1515 days


#10 posted 12-16-2014 05:29 PM

Thanks Jim, great article!

-- Marshall - http://mcomisar.tumblr.com

View Ptownkid's profile

Ptownkid

8 posts in 717 days


#11 posted 12-18-2014 03:39 AM

Z clips are my fave, but the figure eights looks interesting.

View Marshall's profile

Marshall

151 posts in 1515 days


#12 posted 12-29-2014 08:26 PM

One more question – I found the figure 8 fasteners, but they are made for #6 screws. I can use a 1.5” screw – do you think a #6 is going to be strong enough to fasten the legs to the top if the table were to be picked up by the top?

Thanks

-- Marshall - http://mcomisar.tumblr.com

View a1Jim's profile

a1Jim

115201 posts in 3037 days


#13 posted 12-29-2014 08:33 PM

Yep they will hold fine ,just use more figure 8s if in doubt.

-- http://artisticwoodstudio.com Custom furniture

View AlaskaGuy's profile

AlaskaGuy

2406 posts in 1769 days


#14 posted 12-29-2014 08:42 PM

+ on the figure 8

-- Alaskan's for Global warming!

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