Has anyone built their own picnic tables with separate benches? If so, what's the angle to cut the support legs for the table? Is 22.5* a pretty standard angle to cut the legs that hold the table off the ground?
Or, is there a different angle?
I don't think there's a standard angle but your 22.5° doesn't sound appropriate. Figure out how wide the base of the cross buck needs to be (maybe 4" or 6" less that the width of the top) and the height to the underside of the top and work out the angles from that.
If you want help figuring the angles, drop me a PM with those numbers and I'll help you out.
My picnic table is (effectively) resting on two sawhorses
that are joined by a single stretcher about 10 inches off the ground.
The legs on the "sawhorses" are splayed to fall just inside the
shadow cast by the table top. I would guess that angle is less
than 20 degrees.
More important than the lateral stability is the resistance
to racking along the table's length.
When people push on a picnic table, the forces are mainly downward,
left and right. I've never seen one pushed over across the top.
Since a standard picnic table is equally high as it is wide, you could make legs like these:
If you prefer the look of splayed legs, I think somewhere between 10 and 15 degrees would give the right look.
When Norm built his, he used a 20 degree angle but his legs splayed wider than the table top to accomodate the attached seats.
Mike