Groovin’ to a Flat Table Top

With my lumber sourced and getting used to the relative humidity of my shop (such as it is) I needed to address a slight distortion in the slab of bubinga that will become my table top. It curves slightly across the length of the top so that if you put a straightedge end to end there will be about a 3/8” gap in the center. If this bend was across the width of the board, I would call it a cup. As it is running the length of the board, I call it a curve. In the short video accompanying this blog, I call it a warp ... which is a term that really does not describe the distortion accurately. Careful little ear what you hear! 

So, how to fix this slight curve? Fortunately, I found that if I placed the crown of the curve down, and clamped the ends to my worktable’s aluminum frame, the board flattened very easily. To keep it from springing back, I decided to plow three ¾" wide by 3/8” deep grooves and then glue hardwood strips into the grooves to hold the top flat. 

Three grooves plowed on the underside of the table top. The board is clamped flat on a worktable.

Any hardwood species would have done for the splines that I glued in place, but I happened to have a couple of small boards of persimmon lumber, and I chose that. Persimmon is a super dense north American wood. It was the favorite species for golf club heads back when drivers were really made of wood. I am feeling very confident that the persimmon will hold the top flat. 

With the splines cut to length and fitted to the grooves, I glued them in place and “clamped” them with temporary screws.

Once the grooves were plowed and the splines fitted, I glue them in place and used temporary screws to “clamp” them securely. I am going to let the glue cure overnight.  

Allowing the glue to cure.

Tomorrow, I will start building the base. One step at a time.