Work/Assembly table

[tacks Y]

Working on

 my bench and I am thinking of cross strips for more support. The board shows one location 2 x 1 1/2" inside the legs, a 3 x 1 1/2" in the center.

My concern is will this warp the top with humidity change, the length opposite the top grain?   

[Larry]

Several ways to handle it, the one I use depends on the project at hand, and sometimes which side of the bed I get up on.

This is the method I would use for your bench.  Put 3 (or more) 3/8" threaded wood inserts in your top.  Drill three holes in the cross piece.  Elongate two of the holes to about 3/4" long with a router.  These two holes will allow the top to move with changes in humidity.  Tighten the one bolt in the round hole good but only tighten the two bolts in the slotted holes snug.

If you want to know how much your top will move with the weather go here.  You could also calculate how long to make the slotted holes.
Shrinkulator

[Dan_Shade]

Do you have the legs pocket screwed to the top? 

How thick is the top? 

[tacks Y]

I put pocket screws into the 2 1/8" top. It is made from 1" hard maple.

[tacks Y]

Larry, After looking at the Shrinkulator I have a head ache.

I do not think it addresses my concern of shrinkage of the the glued up top compared to compared to the length. So cross grain versus horizontal grain. 

[beenthere]

It will shrink and swell (i.e. move) across the grain. Likely can ignore along the grain movement. 

[firefighter ontheside]

You can build it just like a dining table with aprons.  Attach the top with z clips that allow for wood movement.  Or you can make your own clips out of wood.  I always attach the middle of each end tight with screws to the apron, then use the clips for the rest of each end and all along the long sides.  This allows movement, but keeps the top centered on the base.

[SwampDonkey]

If you do like Larry says with a couple routered slots on the cross pieces, use an elongated expansion washer behind the screw head. These are also used on aprons on the short ends of the table. Wood will likely move 1/16" every 8" in width.

Expansion Washers - Lee Valley Tools

An idea of Chris Becksvoort, the well-known, German born, Maine author/craftsman.

https://blog.lostartpress.com/2019/08/31/meet-the-author-c-h-becksvoort