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Jay Knoll
07-27-2004, 7:42 PM
Hi everyone

I'm trying to build a coffee table base that will support a glass top. I envision it as kind of an open thing, maybe using 1 1/2" square stock. Also, I want all the pieces to intersect in the same plane. I can't envision the joint I would use. Imagine two pieces of wood at 90 degrees to each other, using a lap joint gives me the look that I want. Now, consider adding another piece of wood 90 degrees to the two that are already joined, with the piece lined up with the other two.

It feels like a big wood puzzle, and I am wondering if others have accomplished this in their work.

One alternative would be to put a dowel throgh the lap joint and use that to attach the other piece (actually it would be two pieces since I want to create the effect that the wood is "going through" the joint) but the dowel approach doesn't feel right.

Any thoughts? Am I attempting the impossible? Thanks for your help

Jay

Jamie Buxton
07-27-2004, 8:58 PM
Jay ---

You're not attempting the impossible.

Do you have the tools to bore a hole with square cross-section? Y'know, like the one produced by a hollow-chisel mortiser? Me, I'd make it with a plunge router and square up the corners with a chisel, but there's lots of ways to do it.

Presuming you can make that hole, here's one approach. First do the lap joint of the first two pieces. Then drive a square mortise through the center of the lap joint. Cut the third stick in the middle. On the end of one of those half-pieces, form a square tenon which fits the mortise. Make it long enough that it continues through the mortise and out the other side. Put another mortise in the end of the other half-piece. Impale this half-piece on the end of the long tenon. Done!
This approach is similar to your approach, but uses a square "dowel". The flat faces give better gluing surfaces, and ensure that the pieces don't rotate.
A slightly different way to do it would be to use a loose tenon instead of forming the tenon on the end of one of the half-pieces.
If you're careful, you can get the grain of the two half-pieces to line up so it looks like it wasn't cut in half. Then you'll really have something to puzzle your woodworker friends.

Jamie Buxton
07-27-2004, 9:09 PM
And here's another approach, which doesn't require making a square mortise.....

Imagine you made each of your three full-length sticks from a bundle of four smaller sticks. That is, if your stick were 2x2, the four component sticks would each be 1x1. You might be able to rip the four sticks from one larger piece so that the grain almost matches up when you assemble them back into a single stick. Or you could take the Purloined Letter approach and make them from contrasting woods.

To make the table base, you'll assemble those 1x1 sticks into 2x2 sticks, but at the middle where the joint is, some of the 1x1 sticks will not be full-length. Each 2x2 stick will be made of one full-length 1x1 plus three 1x1s cut in half. That's a sorta half-baked explanation, but it's the best I can do in words. Do your get the picture, or should I resort to my better explanation tool, a drawing.

Jamie

Jay Knoll
07-27-2004, 10:00 PM
Jamie

Thanks I think I get it. If a drawing wouldn't be too much trouble, give it a shot. I'll try a prototype as well

Jay

Jamie Buxton
07-27-2004, 10:21 PM
Here's another way to explain the second approach.

Start with three full-length sticks which are 1x1. Stick two of them together in the middle at 90 degrees. There's no lap joint -- just a face-glued patch which is 1x1. Add the third full-length stick, at 90 degrees to the other two. Like the first joint, there's just face-glued 1x1 patches to each of the other sticks. This assembly looks similar to what you want, except that these sticks just fly past each other, rather than seeming to penetrate each other.

Now take those half-length 1x1s (I think there's 18 of them) and glue them on to the full-length 1x1s to form sticks which are 2x2. If you glue them on correctly, the resulting 2x2s appear to penetrate each other, just the way you want.

One practical thought.... Conceptually I started with 2x2 sticks, and 2x2 sure seems like they'd be thick enough to support a coffee table. However, as you can see by the above explanation, at the joint each stick is really only 1x1. 1x1 seems a little flimsy to be supporting a coffee table. I'd protoype it, but not be too surprised if I found that I wanted to make the sticks thicker.

Jack Young
07-30-2004, 11:34 AM
Jay-

You might consider the arrangement long used for pedestal tables, which is usually a round piece into which sliding dovetails are routed for the, typically, three, not four, legs. In Your case you could used a, say, 3x3 square piece with a sliding dovetail routed into each side. The 2x2 reaches could be dovetailed in their end (as pins) to slide into the center core slots. It was commonly used for quite a long time, still is, in reproductions. It is quite strong, with the possibility of metal bracing mortised into the bottom and out of sight. There have been some articles in recent WW mags on the process, including a tapered sliding dovetail, which is probably overkill for your purposes.

Jack Young

Steve Jenkins
07-30-2004, 12:25 PM
I usually miter all three pieces to achieve a flush corner. Steve

Jamie Buxton
07-30-2004, 2:03 PM
I believe the completed joint which Jay is trying to make would look like the drawing below.

Jamie Buxton
07-30-2004, 7:24 PM
Here is a drawing of my second method for making this joint. (See above messages for an attempt at describing this approach in words.) The brown sticks are the ones which are full-length. The blue ones are half-length. This drawing is at the last stage of assembly, when the last three half-length sticks (shown as a separate group) are about to be glued on the single protruding brown stick to complete the joint.

Jamie

Harry Rigg
07-31-2004, 12:51 AM
Earlier this evening I was looking at a web site of Oregon Woodworkers and saw a picture of a completed coffee table using glass and wood laminated into a large "s" shape. I liked it but it was too modern for the other half of the family. Picture the "s" laid down, with the glass top resting on the profile. The top was rectangular, but I believe an oval shape might have looked better. I think the "s" was made of walnut. The laminations would be a challenge I'd enjoy. If you're interested I'll try to find the site again.

Harry

Jay Knoll
08-02-2004, 12:46 PM
Hey everyone, thanks for the suggestions.

I'm going to go back to the design board for awhile -- actually going on a 6 week road trip, coupled with a stay at the Center for Furniture Craftsmanship in Maine to sharpen my skills.

I appreciate your thoughts,

Jay