Making a Square Table Top From a Rectangular Butcherblock Countertop.

I enjoy using wood for my projects.  If the shape or thickness of a board is not what I need then I can usually reconfigure the wood to make it into what I need for a project. 

This post is about dividing a 25" x 48" x 1.5" butcherblock panel so that the parts can be reassembled into the largest possible square. A little iterative drafting and some easy math is all that is needed.

Math comes in handy to calculate how much area the butcherblock panel has, and with allowance for the kerf cuts to divide it what will be the largest square that can be made with that same area.

Multiply 25 x 48 to get  1200sq.in.. If no material was lost when dividing the butcherblock then the largest possible square would have sides that are the square root of 1200 or 34.61". 

My CNC software has a handy tool for measuring the area within any outline. I'll use a 1/4" diameter router bit to cut the butcherblock into 3 pieces.  The length of those cuts times 0.25" will be the area lost from kerf cuts. Subtract the kerf cut areas from 1200 to find the final maximum size of the square that can be made. 

These are the two lines I cut to divide the rectangular butcherblock panel. 

Subdivided panel.

After being cut the parts are put back together to make a 34.45" x 34.45" square. 

Reassembled Square

This table top will be mounted to a red oak base I made. Two inch thick legs with stretchers that pinwheel and bolt to each other. I'll attach the base to the top with crazy 8 connectors. 

Of course reality comes into play when actually making the parts.   This butcherblock panel claimed it was 25" x 48", but it was 1/8" narrower.  It also came with edges that had been rounded over.  When the small triangle piece moves to its position in the square its bottom rounded edge meets the top rounded edge of the large piece, Trimming those edges to get past the round over shifts the small triangle in, losing about 3/8" of length as it tucks into the corner.   The final "square" will now be 3/8" smaller in one dimension. 

To start I could have ripped off 1/8" of both the left and right side of the initial board, and recalculated the  geometry to make a slightly smaller square from a narrower starting board.  This butcher block panel is roughly 80lbs of wood.  It was a challenge to lift up and place on my CNC.  In place it doesn't slide without a significant effort.  To run it twice through my table saw would have been far more work.  

To clamp the 3 boards together as a square I used 4 long parallel bar clamps. Two laid down in one direction and the other two over those to keep the triangles aligned and in place. 

Reconfiguring rectangles of most lengths and widths is possible.  You start by making sure your starting and ending areas are the same. Subtract the area for kerf cuts you have to make, and verify that the board you start with is actually the dimensions you used for your calculations. In "Mathematical Puzzles & Diversions" by Martin Gardner (←Amazon link) it shows how to cut an equilateral triangle into 4 pieces that can rotate around to make a  square. Some day, maybe, I'll make a triangle from this now-square table top. ;) 

Questions are encouraged!

4D