19 March 2014

Making PC boards the size you need

My shack here in South Africa is equipped only with hand tools and a power drill. Since I have a lot of PC board on hand it makes sense for me to fashion my enclosures from PC board. To make the pieces fit neatly together, I have spent large amounts of time filing the boards into shape. I find that the aviation 'tin snips' I use to cut the PC board work well, but it is very difficult to cut an accurate and straight edge.

Here is a method that works for me. I use a jig consisting of a trimmed piece of particle board about 1ft X 8 inches in size and about 3/4th inch thick. Along the straight edge I secured a piece of aluminum strip flush with the particle board top surface. This strip is screwed on with countersunk screws. At right angles to the straight edge and at one end of the board I have drawn a straight line to act as a guide to ensure the pieces are shaped with the edges parallel and at right angles to each other.


  1. Mark out the PC board and cut it closely to shape using the tin snips. 
  2. Select one of the edges as a straight/master edge upon which all measurements and right angles shall be based. 
  3. Line this edge up with the aluminum strip edge, ensuring that minimum wastage occurs but at the same time leave a small amount protruding to allow a good trim.
  4. Press down firmly on the PC board with one hand to ensure that it does not move during sanding.
  5. Sand off the excess using the circular sanding tool fixed in the drill chuck, operating at high speed. (see pictures below). Don't over do it otherwise the aluminum strip will be sanded also. Keep the drill vertical to the jig.
  6. Smooth the edge further using a file and then fine sandpaper.
  7. Perform the same procedure on all edges ensuring the piece is exactly the dimensions required.
  8. Now use this piece as a template for the remaining boards. The other boards will be marked slightly larger due to the marker thickness. This is all good since they can be trimmed to the required dimensions using the jig as described.
This procedure takes much of the pain and time out of filing. Arguably, making the enclosures turns out to be a bigger and tougher job than putting the electronics together hi!

Jig with aluminum edge, straight-edge, tin snips, markers, sanding tool, finishing file

Hold the board firm and do the sanding outside. PC board dust is no fun!

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