strung up unfinished

I built a construction board last week.  The hole thing took me two entire days.
I bought a 24mm multiplax board, some 40 x 40 mm beech, threaded rods and some bolts. First I drew some lines and started to creat a dip. The top braces will later be fit into this dip before they are glued on to arch the soundboard. This has a structural purpose and will increase the tops stiffness significantly, which allows a thinner plate and a lighter barcing. But that's a hole different story, and fills books...
I have made some of these construction boards before and used small violin makers planes to make the dip. It took me ages. But thanks to the youngest part of my plane family this was done within 10 minutes and it was a joy! I had to stop myself not doing to much as I intended to create a very certain dip with a depth of 2,5 mm from the outside corners to the deepest spot.   

I marked some "chanels" and the outside lines next and began to saw.

 Drilling holes and sawing the chanels.

After the board was finished I made some small pieces of threaded rod which I glued in some beech blocks. Thanks to a huge belt sander these were made fast and easy and they are dead square. I might have achieved this with just cutting the blocks with a circular saw but unfortunately I don't have one. 

My armada of threat roded beech blocks.

 

So here's the finished result. I screwed some pieces of douglas fir to the downside to lift the board and to support against climate changes.