Sizing table legs

[Peter H. Wallace]

  I am going to be making a Harvest table with a curly cherry top and a maple painted undercarriage for a client.   They want the curly cherry top to be made from 6/4 stock, three boards across with bread board ends.   My concern is the weight of the table and corresponding leg diameters to support the top without movement.  Is there a way to determine the smallest diameter of the legs which will keep the table from moving/flexing?  In the past, I have made these table with 3/4" tops supported by turned legs with the smallest diameter being one inch thick.  This was always a very stable table.  However, with a thicker top made from 6/4 stock, mesuring 44" x 84" I am concerned about stability?  Ideas or suggestions welcomed.

Pete

[albreed]

Pete-
I think the stability is as much a factor of the width of the skirt as the diameter of the legs. I'd want a good width there to create a nice stiff "brace" for the legs. The problem with this is always that you need to be able to sit at it without your knees hitting the skirt. If the overhang is enough it might not be a problem, or you can narrow the skirt in the center and leave the width at the ends where it joins the legs.
As far as the turning diameter, it seems that a 1" diameter would be awfully small visually for a table this big; it might need a bolder turning. Structurally, I wouldn't put the 1" anywhere near the top of the leg. It might be OK at the floor, but I think for design balance you want something bigger anyway.-Al

[Antiquity Period Designs, Ltd.]

Pete,

I've made some heavy table top for customers and visually it looks better if the legs are 2? - 2?" square.  Then use Al's suggestions for diameters.

Dennis Bork
Antiquity Period Designs, Ltd.

[millcrek]

This is a table I built about two years ago. It measures 36"X89", 5" inch skirt, 3"x3" legs turned down to a little over an inch at the bottom. All the stock started out at least 6/4, rough sawn and air dryed, I'm not sure what it finished to but its at least an inch. It is very stable in that it is not wobbley at all. However I have had a lot of trouble with the bread board ends . The top seems to expaned and contract excessivley with seasonal change. I have already redone the ends twice. I dont know if it is just this particular cherry, but the last time I changed the ends I put full 1 inch slots in the tenons the pegs go thru and used no glue. Your top is even wider.

[mikemcgrail]

I would think a solid 44 inch top will move at least a quarter inch under normal seasonal changes where I live. This is going to eventually mean  the end of your breadboard "sticks " will easily sit proud 3/16 or so on each end-might want to make sure the clients understand that fact. In cherry, the flatsawn really moves alot more than the quartered. Since it might be problematic to find, 16inch quartersawn boards, remember those nearest (but not containing) the pith(often has cracks emanating from in our local) move the least since they have a higher percentage of quarter oriented material.

[Antiquity Period Designs, Ltd.]

Stain the outer surfaces of the tenons (on the top) and the inside surfaces of the bread board ends before assembly.  When it shrinks you will not see unstained wood.

Dennis Bork

[Peter H. Wallace]

Thanks to everyone who took time to answer my question.   
     I realize the consequence of bread board ends and their movement, no problem for the client.   They understand how the top is going to move.
      I appreciate the tip to stain any table parts which will show as a result of expansion/contraction. 
Thanks again,
Pete