Introduction: Nut Chopper Insert

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Materials:
-  calipers
-  scrap paper
-  vector art software
-  USB stick
-  laser cutting machine (I made mine at the TechShop: www.techshop.ws, using their laser cutter)
-  scrap wood, 3/8” or thinner
-  belt sander

I recently decided that I was tired of the nut “powder” that my food processor made when I tried to chop nuts, so I picked up a used nut chopper (like the kind your grandmother used to use) at the flea market.  OK, so perhaps your grandmother’s nut chopper didn’t have a plastic handle and whatnot, but it *did* have a wooden chopping “block” that lived in the bottom of the jar, which (probably thankfully) my used one didn’t have.  No problem.  Nothing that a little laser cutting couldn’t fix, anyway….

1.  The first thing I needed to know was what size block would fit through the mouth of the jar.  I could have turned the jar upside down and traced the diameter of the jar’s mouth onto a piece of paper, but then I would have had to measure the thickness of the glass (tricky with threads on the outside), do some math and potentially shave/sand down the diameter for the errors inherent in this process.  Instead, with the vector art software and some scrap paper, it was easy enough just to cut a bunch of different sized circles to see which one fit best:
     -  I measured the inside mouth diameter with calipers to get close, and then drew a few circles of +/- 1/16” in multiple increments around that size (in Corel, you can do this easily with the Contour tool).
     -  I cut all these circles on the laser, and fit them through the jar mouth to find the biggest one that would fit without bending.
     -  I then winnowed down my vector art to be the appropriate size circle for the block.
2.  Picking some relatively thin (~3/8”) wood out of the scrap bin in the wood shop, I cut out my circle based on the size determined above.  I used the laser settings for 3/8” wood, and ran the pass a couple of times to be sure that the edges were cleanly cut all the way through.
3.  Taking the piece to the belt sander, I finished both top and bottom surfaces so they were clean and flat.
4.  Popped the “block” into the jar, and, voila… ready to chop some nuts!