Making Pockets for Square Nuts.

I was asked in another forum about my use of square nuts in knock-down projects.  The image above shows the drafting steps I use to make a toolpath for a router bit to cut a pocket that will hold the square nut snug.

From left to right:

1. Know the dimensions of your nut.  A digital caliper is a handy tool to keep near your CNC.

2. The critical shape to use is the side rectangular view of the nut. 

3. In each corner draw a circle the diameter of the bit you'll be using.  I usually use a 1/8"d spiral upcut bit.

4. Draw in the diagonal lines from corner to opposing corner. 

5. Where the diagonal lines cross the initial circles, center another 1/8" circle. 

6. You can delete the diagonal lines and initial corner circles.

7 Trim away the inner sections of each circle, and the corner of the rectangle where they cross the circle line. 

Make sure all the vectors are joined, and you've got a vector shape you can pocket out  to sink that square nut into.  Although my software (Aspire from Vectric.com) has a dogbone tool it doesn't make corners optimized to leave the most flat surface for the nut.  These steps do. 

I buy square nuts from McMaster Carr.  I prefer using stainless steel nuts as they won't rust if the wood has a high moisture content. 

4D