Trestle Table base

[William Hamilton]

So, I'm building what can best be described as a bookmatched walnut Nakashima style trestle table. I'd really like the base/top joinery to be reflective of what was done on the original. I definitely want to emulate that and stick to it. Obviously a great deal of planning should go into managing wood movement, as each slab will be about 23" wide. In looking at these two photos, here is what I think is going on: I think each leg post has a simple bridle joint at the top and bottom, the top appearing to join a cleat and the bottom joining the foot.
I would most likely make these pegged bridle joints for a little more strength. Outside of the cleat that the post joins, there appears to be another cleat/batten, which seems to be screwed into the top. I have done some research and found that it's ok to screw into the top, as long as you accommodate for wood movement by boring and "slotting out" where the screws exit the cleat and enter the slab, to allow some back and forth movement of the screw throughout seasonal movement. I'd like to stick to this, if this is, in fact, what's going on.
As far as the top side of the cleat the that post joins, I'm thinking there are most likely a few pins/dowels in place that help keep the slabs in place. Sound right?
If anyone sees anything different or has any suggestions, please let me know. I'm known to over-research things sometimes but I want to get this right. Much appreciated!

[Harvey Pascoe]

Something to think about: the table top width to base ratio looks awful shaky. Lean on one edge and it looks like it will tip, especially as heavy as that top is. I made mine with the base feet at 80% of the top width. That looks to be about 50%. ALso, is that stretcher low enough to provide stability?

[Mike Cruz]

Actually, my diningroom table is a near 4'x8' slab (not glue up) natural edge walnut table. The base is only 24" and it is plenty sturdy. We commissioned my old boss (before I started working for him) to make the table for us. We've had it for about 15 years with no tipping issues. The pic doesn't show the base, sorry, but it is similar to the obove pic. BTW, our table top is at least 6/4 if not 7/4.

[William Hamilton]

those 2 photos were of actual Nakashima tables, so right or wrong I was assuming he had his design built around the various possible stresses. I know he had a degree in architecture and knew joinery etc. inside and out, so I will probably stick to this design. The design sketches I came up with (sorry, don't have photos of them) basically took his dimensions and exponentially scaled them to suit my slabs. My slabs will be about 23" x 74" with a 1/8" gap going down the center of the table... probably five 4.5" butterfly keys evenly spaced down the center as well. I have to take a good 24" off one end of each slab. The hard part is choosing what figuring to lose.
I'm planning on taking the thickness of the slabs down to about 1.5".

[William Hamilton]

ps I got these two slabs of walnut, 25" x 99" x 2.5", for $370!

[Rob Sack]

ps I got these two slabs of walnut, 25" x 99" x 2.5", for $370!

It's a shame you will taking off about 40% of the overall thickness.

[Jamie Buxton]

That first photo is baffling. He apparently has a horizontal beam firmly bridle-jointed to the post. So why include a second horizontal beam, and put the screw holes in it? I suspect something more is going on, but don't know what it is.

And while I'm being baffled, I also don't understand what looks like it might be some sort of tusk tenon. Maybe the wedge is dovetail-shaped in cross section, and tapered too?

I'd sure like to see more photos of that area.

[Chris Friesen]

That first photo is baffling. He apparently has a horizontal beam firmly bridle-jointed to the post. So why include a second horizontal beam, and put the screw holes in it? I suspect something more is going on, but don't know what it is.

And while I'm being baffled, I also don't understand what looks like it might be some sort of tusk tenon. Maybe the wedge is dovetail-shaped in cross section, and tapered too?

I think the top has battens screwed to it to keep it flat, then basically just sits on the base. I think you nailed the design of the tusk tenon though.

[William Hamilton]

Rob, after thinking about it I considered what you said about the thickness and decided to go thicker on the top. It would be a shame to lose that much over aesthetics. It'll still look good at 2" or 2.25" thick.
As for the "tusk" or "keyed tenon", I found another photo, dead straight on. To me, it looks like a wedged tenon, in a mortise that is tapered inwards from the sides, as well as tapered in from the end. Thoughts? I dig this whole "how'd he do that?" thing. I am guessing George did this mainly for visual appeal; adding to the whole "exposed joinery" Shaker look and feel. I do like the fact the you can see the tusk from the end, instead of part of it being buried in a mortise. I have to do this right though, any screw ups and the joint won't be strong.Tusk.jpg

[Jamie Buxton]

As for the "tusk" or "keyed tenon", I found another photo, dead straight on. To me, it looks like a wedged tenon, in a mortise that is tapered inwards from the sides, as well as tapered in from the end. Thoughts? I dig this whole "how'd he do that?" thing. I am guessing George did this mainly for visual appeal; adding to the whole "exposed joinery" Shaker look and feel. I do like the fact the you can see the tusk from the end, instead of part of it being buried in a mortise. I have to do this right though, any screw ups and the joint won't be strong.Tusk.jpg

Yeah, that's what I was thinking it was. Maybe he did it that way because the hole for the wedge can be made with a saw and a chisel. The usual way to design these things requires boring a long hole, and (ideally) having it come out in the correct place.

[William Hamilton]

cutting a tapered mortise might be a little tougher than scribing out and cutting what he's done here...

[Jamie Buxton]

cutting a tapered mortise might be a little tougher than scribing out and cutting what he's done here...

The way I do it, it isn't a tapered mortise. It is a slanted mortise. It is basically the same cross-section everyplace. When the joint is assembled, there is some unoccupied air space in the middle of the post, but nobody can see it.

[William Hamilton]

when all else fails, go to the source... I went to nakashimawoodworker.com today and actually discovered something about how he attached his tops to his trestle table bases. The caption for this photo reads. "The base easily disassembles by removing tapered pegs and wedges, yet is extremely sturdy, and provides the most leg room of any of our table designs."
Just judging by what I see, the battens he attached to his slab bottoms must have little mortises on their outside facing edges for those two tapered pegs to fit in. That table top stays in place because any force directed towards either end would be transferred to the top of the opposing table leg. Since the pegs are tapered, they can't be forced out. At least that's what I think is going on here. It's pretty smart. Simple, yet smart.Picture167.jpg

[Pat Barry]

William, I suspect that the two battens you see at the top are actually two separate pieces. One is attached to the tabletop, and the other is attached to the leg upright. When the two battens are aligned to each other, the tapered pegs are driven home and pin the battens to each other. The stretcher goes thru the leg upright in a thru mortise and the wedge is slipped in to lock it in place. Nakashima does a great job of making this easy to take apart and strong.