In order to make sure the table top I will be gluing will be flat and so I can keep the thickness I have milled to separate board, I am making cambered cauls for clamping. I want the boards to retain their milled thickness of 13/16 inches so I can cut curved edges to the table top.
I read somewhere during my research that softwood lumber is okay for clamping cauls. I bought three 2 by 12 by 8 feet redwood planks today at Lowes. I selected the planks that where very straight. Also most of these boards do not have any knots in them.
I am generally following a Fine Woodworking article to make these cambered cauls by using my planer.
Prior to jointing a surface flat I decided cut the eight foot lengths of the three planks in half and then rip the four foot planks into thirds. The ripped widths thus is oversized to 3 1/2 inches. This leaves me three 3 1/2 inch wide boards, four feet long.
Then I jointed one surface flat and and an edge square to it. From there I ran the 18 boards through my planer so they all have the same thickness.
Next I ripped each of these boards to 3 inches width with the squared edge up against my table saw’s fence.
I then crosscut these boards so I have three sets of six boards to the following lengths: 28 inches, 38 inches and lastly 44 inches. Then with a rule I marked the center point on the edge I am going to camber a slope to their edges.
I clamped a stop on the planer. Laid the center line past the cutters and then planed off 1/16ths inch on the short boards, about an 1/8th inch off the 38 inch long boards and bit more from the 44 inch long boards.
They are good to go as they are, but I also bought six 6 inch long bolts and six 8 inch long bolts. Tomorrow I will drill holes in the ends of these cambered cauls so I can bolt them to sandwiched table top between them.
I drew squiggle lines on the cambered edges so I can easily determine what edge to apply to the table top when I glue it together.
Tomorrow I will also rub on paste wax on all surfaces of these cauls. I will then determine if I should apply any packing tape to the cambered edge in order to avoid having the surface adhere to the table top when I glue and clamp it.
-- --- Happy Howie