Attaching metal legs to a slab

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Forum topic by Jaydee829 posted 07-14-2016 07:28 PM 462 views 0 times favorited 10 replies Add to Favorites Watch
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13 posts in 335 days

07-14-2016 07:28 PM

Topic tags/keywords: slab koa

During a recent trip to Hawaii I somehow bamboozled my wife into buying a beautiful 5’x15”x1.5” slab of Koa for a hall/sofa table. When I asked her what she wanted to do about the legs, she said she wanted to go with metal legs and found a couple of places that are selling some that she liked. This leaves me to try and figure out how to attach these legs to the slab.

My problem is this: currently we live in an ideal environment for woodworking (Mojave Desert); however, we will likely be moving to the Dallas area in the near future, where there is significantly more humidity. Therefore, I need to attach the metal legs to the slab in a manner that will allow the Koa to move as the moisture content changes.

My thought was to glue a couple of cleats to the koa across the grain and then use a t-nut in a groove on the cleat and a bolt to attach the metal legs to those. This would allow for easy disassembly if further moves are required and should allow the koa to move as it wishes.

Thoughts on my approach? Overly complicated? Impressively original? doomed to failure? I would love to get some feedback as this is my first project using a slab.

-- Justin, California

10 replies so far

View Aj2's profile


772 posts in 1310 days

#1 posted 07-14-2016 07:40 PM

No cleats should be glued across the grain.No no no!
What’s the Mc of the wood right now?
Is the slab flat now?
What’s the Rh of the environment your taking it to?
These things matter and it takes experience and luck to make the right decisions on how to store and handle the wood.
The koa I have worked was very stable but it was also dry.
15 inches is not very wide but you still need to allow the wood to shrink or expand.
Some slotted tabs in the corners of the stand and screws is one way.
Good luck.

View Jaydee829's profile


13 posts in 335 days

#2 posted 07-14-2016 07:51 PM

I guess I should clarify, the cleats I was thinking of making would have the grain oriented in the same direction as the koa in order to restrict movement as little as possible. Essentially they would have radial expansion in the same direction.

I don’t know the current MC of the wood now (picked up a moisture meter on Prime Day!), its been in my garage in a RH of ~10% for several months now. RH of the Dallas area is between ~50% and ~80%.

-- Justin, California

View Aj2's profile


772 posts in 1310 days

#3 posted 07-14-2016 08:33 PM

I do think it’s better to go from Low Rh to high Rh.So that’s in your favor.
Allow for movement you cannot stop it.
Maybe I’m not understanding your plan.
If it’s been in your care for several months and hasn’t warped you should be golden.

View bobasaurus's profile


2804 posts in 2696 days

#4 posted 07-14-2016 08:43 PM

You’ll need to let that slab dry for quite a while before working it. Make sure it is stickered properly while drying to avoid cracking and warping. Seal any exposed endgrain. I’ve heard horror stories of koa furniture ruined when shipped to dry climates.

-- Allen, Colorado (Instagram @bobasaurus_woodworking)

View AandCstyle's profile


2624 posts in 1769 days

#5 posted 07-14-2016 09:00 PM

Jay, I might not be understanding this correctly, so ignore this if I am. I am picturing 4 metal legs that are not attached to each other in any way. If that is the case, just screw the legs into the bottom of the slab. The legs will move independently of each other, but will float with the movement of the slab. FWIW

-- Art

View rhett's profile


737 posts in 3180 days

#6 posted 07-14-2016 09:03 PM

On my metal bases, I drill a 3/8” diameter hole in the mounting flange, then screw the base on with a pan head screw and a fender washer.

Plenty of room for expansion and contraction of slab tops.

Hope that helps.

-- Doubt kills more dreams than failure.

View Jaydee829's profile


13 posts in 335 days

#7 posted 07-14-2016 09:19 PM

Allen: Luckily the koa was relatively dry when I bought it and had already been surfaced somewhat, so I don’t think I will have too many issues with cracking or warping (none yet anyways). I will definitely keep an eye on it and I will check to see what its MC is once I get my meter on Friday.

Art: The legs are actually two rectangles, one on the left side and one on the right. So simply screwing them in would restrict radial expansion.

For ease of disassembly and allowing movement, would threaded inserts paired with slots in the legs (perpendicular to the grain) be sufficient to allow movement? I think this is what Aj2 suggested, but with the addition of threaded inserts.

Thanks for all of your help!

-- Justin, California

View Aj2's profile


772 posts in 1310 days

#8 posted 07-15-2016 04:05 AM

See the tabs on this base.
The hole is over sized with a large washer on the panhead screw the wood will move as needed.
And everyone stays happy including Mother Nature.

If your base doesn’t have tabs add some L brackets from the Borg.And make the holes so the wood can shrink or expand in its width.

View Jaydee829's profile


13 posts in 335 days

#9 posted 07-15-2016 02:33 PM

Thanks for the help, using the panhead screws and washers sounds like they will work perfectly. I’ll be sure to post some pics when the project is complete!

-- Justin, California

View CaptainSkully's profile


1449 posts in 3071 days

#10 posted 07-16-2016 05:42 PM

Yes, make 1/2” slots in the cross-grain direction in the metal attachment points. The fasteners in the wood will move as needed. Have fun with the koa. It’s a very brittle wood and I’ve had lots of trouble with tear-out.

The breadboard ends on my first dining table in Austin moved over 3/16” on each end during the course of the year!

-- You can't control the wind, but you can trim your sails

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