removable rockers

[Andy]

I'm working on a mission style rocking chair, and I'm trying to figure out whether it's feasable to make the rockers removable. (It would then fit relatively easily in the back seat of a normal car, which would be nice, since I'm planning on driving it from NY to MI at Christmas, and it will probably be moved several times after that.) Rockers and legs are red oak, about 1.5" square in cross section. My ideas so far:

1. Use cross dowels (aka barrel nuts?), with a bolt up through the rocker into the cross dowel which is inside each leg. Inserted from the back, cross dowel should be minimally visible, or could be countersunk and plugged (plug not glued). Any sources for larger (i.e.

3/8-16) cross dowels? I found some at Woodpeck.com, but they seem overpriced. Rockler, Woodcraft, etc. only seem to have 1/4-20, which would work, but I like to overdesign things whenever possible...

1. Make tenons on the ends of each leg, which go through (or most of the way through) the rockers, then pin them in with 3/8" wood dowels through the sides of the rockers (not glued). I like the simplicity and lack of hardware with this option, but I imagine the dowel might loosen itself up over time.
2. Threaded inserts in ends of legs - I don't like this idea very much, as it relies on holding power of threads in end grain, even if they are large threads. Fine for a while, I'm sure, but I'm really intending this to be an heirloom-quality piece. I'm ruling out simple wood screws altogether for this reason.

What do you think? Other ideas? Comments/criticisms/advice? Should I forget it and glue in good-ol' M&T joints? Thanks much, Andy

[whit3rd]

The prospect of loose joints at the rockers, which are under high stress, is disturbing. I'd want those tenoned and glued.

How about the undercarriage attachment point to the seat? If you're using wedged through tenons, consider wedging from below (i.e. drive in a tapered wedge at 45 degrees, from below the seat into each of the support posts). That way, it won't come loose in use (you're sittiing on the seat, it won't rise off the posts), and it can be disassembled by gently hammering the wedges from above. There will be a clearance slot on the underside of the seat, as the wedge enters from off-axis, but no other visible disturbance to the design. Probably you'd need to replace the wedges with new ones to reassemble, and of course the new wedges will need to be cut flush after assembly.

Tricky part will be to saw the correct shape slot in the tenon, which you want to tighten at the top face first.

You could also make access from below to the wedge (cut a mortise at right angles, so a taper driven into the mortise pushes up a conventional wedge), and skip the diagonal cutting. The wedge would have to be thick enough to be driven from its tip.

[Leuf]

Seems like a good application for a dovetail to me. The forces are only in one direction, so a dovetail is not going to come apart even without glue. I don't think the joint is going to get loose from being taken apart half a dozen times.

-Leuf

[Andy]

I like it... I like it a lot. As long as the dovetails are tight enough to hold, but loose enough to tap apart. I'll definitely consider that - thanks for your input! Anything else I haven't thought of? Andy

[Jay Pique]

On the dovetail, I'm guessing you'll cut a single tail on the end of the leg, which will slide laterally into a pin cut into the rocker - a short sliding dovetail. Stopped on one side? I'm a little worried about the effect of rocking on the joint. I think that the forces are a bit more varied than just straight compression. Will you pin it into place?

I'm definitely intriqued by the idea. Let us know what you go with.

JP