Arrow of Light – Engraving

To personalize each plaque, I’m going to engrave the Pack information, the year, and the boy’s name.  In HeeksCNC, engraving is just a profile operation with the ‘tool on side’ parameter set for ‘on’.

That isn’t to say that engraving is easy.  It’s not.  At least it’s not easy to get decent results.  The complexity comes from primarily two issues.  First, with engraving we’re not usually cutting very deep.  In fact, if we were engraving in metal, the depth of cut would be only a fraction of a mm.  So if the top of the material isn’t perfectly flat or if the CNC machine isn’t perfectly aligned, a V cutter will make a deeper/wider cut in one place and shallower/narrower in another.  The red oak stock I’m using has quite a bit of variability in thickness and I couldn’t get results I liked.  I chose to use a 1/16″ two flute router bit and cut deeper – a full millimeter.  Since it’s a straight sided cutter, the width is consistent even if the depth varies.  The final results were acceptable.

The more challenging problem with engraving is fonts.  Truetype fonts are vector based so they scale well and you would think they would lend themselves naturally to CNC.  However, the geometry of the font defines curves that enclose the entire letter.  So a capital ‘L’ will have two parrallel lines defining the vertical part of the letter.  A profile operation will outline the letter and leave an island in the center.  For engraving, what’s needed is a ‘stick font’ or a centerline font that has only a single line down the middle of each letter.  There aren’t many fonts available like this.  The only ones I know about are the Hershey fonts.  Fortunately they are bundled with Qcad and work with HeeksCAD.  Not much choice, but it’s something.

Leave a Reply

Your email address will not be published. Required fields are marked *