Replies

1. 
   JohnWW | Apr 12, 2007 07:15pm | #1

   It is worth having a good quality machinist's square in the shop to test for squareness, but they cost a fair amount of money.  There is however a simple but sensitive test for a square crosscut that doesn't require a pricey tool.

   The test requires only a piece of straight stock, 3/4" thick, around 6" wide and 3' long.  A piece of MDF will fill the bill but solid wood will also serve.  

   If you are using real wood, joint one edge of the board straight and then rip off the other long edge to get the board even in width with two straight edges.  Don't run MDF over a jointer, the glues in the panel will instantly dull the machine's blades.  With MDF you can usually use a factory edge of the panel and expect it to be straight.  For the test to be accurate it is important that the long edges of the test board are quite straight.

   Now use your sled to cut 6" off of the end of your test board.  Take the cut off piece and flip it over, front edge to the back, and place the two freshly cut ends back together.  Now sight down one of the long edges of the reassembled board.  If your fence is set at exactly 90 degrees, the edge will still be straight.  If the fence is off, you will see a kink at the point where the two boards come together.  You can also place a straightedge, it only needs to be a foot long, against the edge of the butted boards to test if the combination is straight.

   John White 

    

1. 
   c4th | Apr 12, 2007 11:33pm | #2

   Thank you very much for your quick responce and good test idea.