Figure 8 Table Top Fasteners - Need some tips

I bought a pack of figure 8 table top fasteners for my mission style coffee table. I needs some tips.
My table is roughly 22" X 48". Should I use 3 fasteners for each rail and 1 for the middle of each stretcher? The fasteners are about 1/2" in one end of the figure 8 and 5/8" at the other end.. Which is the optimal end to be on top of the rail and stretcher vs. the table top. (ie the 1/2" end or the 5/8" end).
I realize the fasteners on the rail end can pivot slighty but what about the stretcher ? If I mount them perpendicular to the stretcher they can't pivot it the table top expand. Should I mount them at a 45 degree angle on the stretchers or should I even skip mounting them on the stretchers?
Lastly should I mount them so they face inward or outward from the rail and stretcher.
(P.S. a forstner bit seems optimal to embed them in the rails and stretchers.)
TIA
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On Sun, 24 Dec 2006 17:32:20 -0800, henny wrote:

Had occasion to do some repairs on a desk the other day that was more or less in the Mission style and about 80 years old, so I believe that what I saw when I had it apart can be taken as at least somewhat authentic.
The desk had two pedestals, each with four legs. On top of each leg was one of the figure 8s (actually just a piece of strap iron with two holes in it). The ones on the outer legs (i.e. those toward the ends of the desk) were oriented more or less parallel to the grain of the desktop. The ones in the inner legs were oriented at about 45 degrees and positioned so the screws cleared the aprons between the pedestals.
When screwed down the top was well secured relative to the pedestals and when force was applied the whole desk moved rather than the top sliding on the pedestals, so that seems to be an adequate fixing.
Note that the straps were not embedded, they rode on top of the legs and the top rode on top of the straps, so there was a space between the top of the pedestal and the bottom of the desktop.
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--John
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"henny" wrote in message

Generally speaking, in woodworking parlance, tables have "aprons" (at the top of the legs, upon which the top (hopefully) rests).
Don't make it difficult, here's how I do it:
Use 4 figure 8's if you can get away with it, one on each apron.
If you really feel it necessary, use 6, 2 evenly spaced on the top of the long aprons, and 1 each in the middle of the two short aprons.
If using four, in the top of the middle of each "apron", use a Forstner bit to drill the 5/8" "mortise" for the large end of the figure 8 fastener.
Let the bit hang over the inner edge of each apron about 1/4" while drilling (just be carefull that the center of the "mortise" (where the screw goes) is far enough away from the edge to not split the apron when the screw is driven home!)
With the countersink up, drill a small pilot hole and fasten snugly with provided screw (angle the fasteners slightly so they are not perpindicular to the cross grain of your table top and thus have room to move with the any expansion contraction).
They don't have to be loose ... don't worry, when the wood moves, they will move.
With the table upside down on a flat surface and positioned over the top, drill a small pilot hole if necessary and screw the small end if the fastener snugly into the underside of the table top with provided screws.
That is ALL you need to do.
--
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Last update: 12/24/06
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Those figure eights work fine for holding across the grain while allowing some swing either side to accommodate wood movement. I wouldn't use them on the long grain unless they were out of line, as the ones Clarke recalls, with clearance for them to swing into the apron area.
The best for the long grain, which does not move significantly, are these http://www.rockler.com/findit.cfm?pagex4 which require a groove. Since your wood will be pretty dry during heating season relative to summer conditions, unless, of course you use air conditioning to cool and dry things, you' want to keep the end a quarter or so off the bottom of the groove to allow expansion. If you're year-round drying, perhaps half that. You can get a bit more precise by looking at your species and grain orientation and then at the fpl _Wood Handbook_ for shrinkage figures.
For example, you say Mission, so let's presume white oak, which shrinks tangentially about 9% of width from 30% to 0% moisture content. Means a safe figure is 3% of width between fasteners, since it's pretty linear. 22" yields about 5/8" for a 10% annual swing. My house. Winter is as low as 5, summer approaches 15%. You can game your actual wood and conditions a bit if you must.
Three along the long rails, two on the short should be a good mix. Be sure to apply coats to both sides of the tabletop to keep things even in the moisture uptake department, saving yourself the lift at the edges of the table.
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Z clips are also best for crossgrain. Either way, you want to screw the top down in the middle of the crossgrain.
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