The two cross beams will tie the entire cabinet together, and also support the middle of the slate.
Most well built tables come with three additional beams which are installed perpendicular to the cross beams,
and go lengthwise up the table. Originally, I planned on installing the extra beams, but after installing
the cross beams, I deemed it overkill for an 8' table. However, if I were building a 9' table, I think it
would have been a good idea.
Most build beams from 2X8 Douglas Fir, but I've seen Fir do Yoga before -- I've seen a 2X4 twisted so that
one end was laying on the floor, and the other end was turned ninety-degrees and two feet in the air.
So, I couldn't possibly feel comfortable knowing that this might warp and "de-level-itize" my table.
For an alternative, I chose to glue two 8" wide pieces of the Oak plywood together to form my beams.
Installing the Beams
I took the two boards and spread out an ample amount of glue, then clamped, and nailed them together.
They ended up very strong and straight.
I installed the beams to be flush with the top of the Cabinet, and to line up directly under the seams of
the slate. To find that point, I measured the table length, and divided that in half to find the middle
point of the table. I then did the same to the middle piece of slate. I then measured from the middle of
the slate, to the seam, to find the distance from center to seam. I then projected that number from the
middle of the table to find my mark. I relearned a valuable lesson here...double check measurements.
When I installed the beams, I noticed they were obviously off of alignment. I remeasured, and figured out
that I was off exactly one inch on one side (somehow I added an inch in my head along the way.)
If I had a 15-degree slope, I would have to cut angles on the end of the beams beams to fit snugly. I simply cut them square to fit the inside dimension of the cabinet, then glued and screwed them in from the outside of the cabinet.
I then installed the glue blocks around the beams to give it extra support.
At this point, I am ready to install the trim to the cabinet. BUT, I decided that it would be smart to get
the Slate on board so the settling could begin. So next I will install the poplar slate support,
and throw the slate on.