C Channel for dining table build

[George Yetka]

If your worried about getting too close to the top you dont have to fully sink the channel. as long as the the flanges and part of the web are sunk. I would stick to steel it has a lot less flex. I have been purchasing these from Fractal designs canada https://fractaldesigns.ca/collection...-reinforcement The fit and finish have been very good. Make sure the holes are oblong so the wood can move in them slightly. And the Ez-lok SS inserts are very nice but get very expensive if you have quantity. The Rampa ones are also pretty nice and quite a bit cheaper

[Jim Becker]

Not fair. George Nakashima is an artist whose knowledge and skill far exceed a collective of knowledge and skill on this forum. He's also sourced a lot of those slabs himself, right from the tree, dried them, aged them, etc and could tell you exactly where on/in that tree the particular piece came from..

I've been in the slab storage at the Nakashima compound...what a treat. At the time, they indicated there was still material in there that George had selected but just had not spoken as to what it wanted to be. The place I buy most of my domestic lumber is one of the suppliers for them.

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I think that the individual slab or construction is what determines the value of using c-channels or not. It's just a method to use when warranted by the specific project and nothing that folks should scoff at. My reference to Blacktail had nothing to do with the resin work which is certainly a subjective thing, however. It was all about the use of and installation method for c-channels because Cam does it very well and very consistently.

[Michael Burnside]

I imagine you know the answers to your questions so why the challenge?

Ever see a C channel in a Nakashima table?

John

My point was that there are so many variables to woodworking that using them is sound judgment, but you do you.

And to compare to Nakashima is absurd. They probably have moisture content measurement down to a science when your charging THAT much for a piece of fine furniture.

[Edward Weber]

Not fair. George Nakashima is an artist whose knowledge and skill far exceed a collective of knowledge and skill on this forum. He's also sourced a lot of those slabs himself, right from the tree, dried them, aged them, etc and could tell you exactly where on/in that tree the particular piece came from.

Edit: I'm not implying that every slab turned into furniture needs a steel c channel but when large enough and enough variables are at play, it doesn't hurt to be safe. That said, it's nice to be able to use the actual base to keep things flat (when appropriate and aesthetically correct).

Wow, how to unpack all that.
It doesn't take a genius or a woodworker of Nakashima's caliber to understand that a plank, or 3 planks glued together like the OP's project, can bow or cup. All you're trying to accomplish is to restrain the wood from moving. This can be done in many ways, a metal channel is just one of them. Not my personal choice but it does the job.

[John TenEyck]

Not fair. George Nakashima is an artist whose knowledge and skill far exceed a collective of knowledge and skill on this forum. He's also sourced a lot of those slabs himself, right from the tree, dried them, aged them, etc and could tell you exactly where on/in that tree the particular piece came from.

Edit: I'm not implying that every slab turned into furniture needs a steel c channel but when large enough and enough variables are at play, it doesn't hurt to be safe. That said, it's nice to be able to use the actual base to keep things flat (when appropriate and aesthetically correct).

What's not fair? There are many folks here that understand how wood moves, what causes it, and how to deal with it. And they know the best way to deal with it is to make sure the wood is at equilibrium with their shop before using it, to work it in stages, and to finish all surfaces equally. Nakishima was no smarter than anyone else in this regard. He was just willing to adhere to a process that gave him wood that would remain stable. The guy was a great woodworker, not a wood whisperer.

John

[Christopher Charles]

Maybe I missed it, but what do you plan to use for a base? The slab and base can work as a system to achieve the same effect, depending on the details of the base.

Best,
Chris

[John Kananis]

Wow, how to unpack all that.
It doesn't take a genius or a woodworker of Nakashima's caliber to understand that a plank, or 3 planks glued together like the OP's project, can bow or cup. All you're trying to accomplish is to restrain the wood from moving. This can be done in many ways, a metal channel is just one of them. Not my personal choice but it does the job.

I don't disagree with anything you said. It's basically the last paragraph you quoted.

What's not fair? There are many folks here that understand how wood moves, what causes it, and how to deal with it. And they know the best way to deal with it is to make sure the wood is at equilibrium with their shop before using it, to work it in stages, and to finish all surfaces equally. Nakishima was no smarter than anyone else in this regard. He was just willing to adhere to a process that gave him wood that would remain stable. The guy was a great woodworker, not a wood whisperer.

John

The juxtaposition isn't fair. You're comparing Yo-Yo Ma to a guy practicing violin in his basement. The knowledge, experience and resources did not necessarily make George Nakishima smarter but it did afford him wisdom that exceeds that of most. Imho

[John Kananis]

Jim, I'm envious. To my shame, New Hope, PA isn't that far from me but I haven't been.

[Richard Coers]

I suggest you have an engineer buddy figure out what strength your C channel has. I bet you a box of donuts the wood is stronger when it moves than what the metal can resist. I saw a desk that the wood movement of the slide out writing surface broke the entire side off the desk when it expanded in the spring. Just adding metal isn't a solution if it's weaker than the wood. All this steel under a table is a very recent on-line trend created without real knowledge of what they are attempting. A very large percentage of on-line new woodworkers have no idea about wood movement in the first place. Look at reddit, those folks ignore it constantly and there must be no one with a YouTube entertainment channel that teaches them.

[Jim Becker]

Jim, I'm envious. To my shame, New Hope, PA isn't that far from me but I haven't been.

Check their website, as I believe they historically have public hours on Saturday mornings, but I don't recall the details and if it's year-round. These regular tours are not comprehensive, but give a nice view in general of what goes on there. A number of years ago, the Michener Art Museum in Doylestown had a benefit event at the Nakashima compound which not only included a box lunch and a talk and other interaction with Mira and Kevin, but also a tour of EVERY building on the property. It was mind-boggling. They haven't done it since, to the best of my knowledge, but I'm so thankful that Professor Dr. SWMBO and I got to do that event. It was worth every penny of the fifty bucks donation! The museum has a Nakashima room as a permanent display and gosh darn it, you can sit in several Nakashima chairs and fondle a whole bunch of other things.

[Michael Burnside]

Maybe I missed it, but what do you plan to use for a base? The slab and base can work as a system to achieve the same effect, depending on the details of the base.

Best,
Chris

Very good point. Before I felt comfortable building my own full-sized table, I hired a local artisan to build a 36" x 9' table for our dining room. He brilliantly constructed a large X frame metal base, as my wife wanted a modern flare, and then inset the top along the width of the table in two places, making for an effective c-channel.

[Edward Weber]

In all but the most extreme circumstances, there is no need to introduce an external metal brace.
Mortise a hole through the blanks and insert a proper sized square tube. It won't bend, it can float and it won't bee seen. You can also do this with round rod or pipe.
This can all be inserted during glue up and will be unseen to anyone.

Routing out 3/4 channels and securing C-channel to the underside is a rather crude way to approach stiffening the top IMHO.

[John TenEyck]

FWIW, aluminum has 1/3 the stiffness of steel. I'm certainly not advocating any C-channel, but if you must, use steel. Also, FWIW, a square tube will be about 4X stiffer than a C-channel of the same dimensions and cross section.

John

[Christian Hawkshaw]

In all but the most extreme circumstances, there is no need to introduce an external metal brace.
Mortise a hole through the blanks and insert a proper sized square tube. It won't bend, it can float and it won't bee seen. You can also do this with round rod or pipe.
This can all be inserted during glue up and will be unseen to anyone.

Routing out 3/4 channels and securing C-channel to the underside is a rather crude way to approach stiffening the top IMHO.

If your top is comprised of wide boards, what method do you use to make the mortise? I am assuming one length of tube going across the width of the table, but not exposed on the sides. So you could have some through mortises that could be quite deep if you have wide boards.

[Jim Becker]

That's the same question that came to my mind, Christian. Same for slabs. Internal bracing would be a tough row to hoe, although I certainly like the idea in principle.