Hi all,
I’m a beginner woodworker from The Netherlands and i’ve been reading here quite alot, so thanks for that! One of my first projects is an outdoor table with a live edge slab. The frame is made of 4″x4″ oak, the live edge is beech 2″ – 2.5″ thick.
After bringing my slab outside it started cupping / twisting. Although i have steel C-bars embeded into the edge, this doesn’t stop it.
Do you have any advice on how i can flatten this slab again and keep it so. Any advice is appriciated.
Thanks! (See attachements)
Replies
Bring the whole thing inside to where the top was flat and wait for it to flatten out again. Then bolt it to the frame through the horizontal tops as securely as you can. Elongate the holes so it can move seasonally. It might hold it flat, it might not. It could even twist the frame. The slab wants to twist and it will keep trying. That frame might be beefy enough to stop it depending on how you built it.
Thanks!
“[Deleted]”
With a slab it's likely heartwood and sapwood in a fight they'll never quit fighting - at least where the twisting is concerned.
Seems like I remember reading that Nakashima had a significant reject rate from excessive movement (twisting and bowing) with slabs he had set aside seasoning. Could have been somebody else, but he was the grandfather of all of this so I'm thinking my memory is not failing me on this.
If you bought the thing last week, and you're trying to make a table out of this week, you're making a huge mistake.
Thanks, yeah it is going to be a fight..
It's just sitting on top of the base? Try flipping it and set ,I don't know, maybe a set of barbells on it and see if it corrects itself. I suspect that its, the slab,is not fully seasoned. If there's a finish do it on all sides. If it doesn't come all the way flat from the weight ,which I bet it doesn't, you could resurface the top , plane,belt sand, drum sand, router on a frame jig..you pick. Then mount it onto the base. Make slotted holes in the base. Me, I might use threaded inserts into the top and bolt it down or nice beefy lag screws. Go stainless. I'd use a nylon washer under a metal washer so that it can slip when it expands or contracts. So,not crazy tight, it is going to move laterally so let it.. It might fight you even after you do all of this but it's an outdoor table. A little funk is permitted,maybe preferred!
It currently is just sitting on top. I had planned to bolt them to the frame using the mentioned threaded inserts. Thanks for the sugestions!
By the way,what do you think that metal was going to do? If you could bend it by hand there's not enough beef. I'd lose it ,it's not helping.
So, once upon a time people knew about wood. Even as a 10 year old mom sent you out to split kindling or you split rails before launching your political career.
Someone I knew did their roof with hand split shakes but after they were installed they curled upwards toward the sky. An old hillbilly guy who knew a thing or two looked at it and said "That's because he didn't put them on in the dark of the moon"! Next time you set it out ...
The metal underneath the slab? That C-bar is extremely tough and not bending at all, but I think i made a mistake embedding it too far into the slab (the side are 1 inch into the slab). This resulted in the wood between the C-bar cracking and not being able to hold the slab flat.
And.. yes, not many people know wood - I hope to atleast learn from the mistakes i've made with this project.
This challenge is a tough one.
Were it mine, I would defeat it by ripping the top into three pieces, then jointing the edges and gluing (polyurethane glue is my favourite for outdoors as it is totally waterproof) the panel back together flat. You will be able to keep the live edges and you will only lose about 10mm total width.
This will account for the warping in its current environment.
If it then bows afterwards, take the top off, use it for something else and try another top!
You never bolted it down? You gotta connect your joinery asap on any project. If that base is beefy enough maybe you can clamp it back to flattish and put yours screws in.
I’d run multiple saw kerfs down the length of the slabs bottom and then bolt it to the cross frame as planned — with elongated holes to accommodate seasonal movement. You can then plug the end gaps with scrap to hide the kerfs.
Yep, simple and effective!
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