It is hard to believe that it was almost ten years ago I witnessed a CNC router in action for the very first time. I was fascinated and simply had to have one! Although I had been in the creative end of the three dimensional sign business for most of my life I didn't really know what I would do with one of these machines - but I just knew it could do fantastic stuff.

Along with the CNC router I discovered the wonderful material called Precision Board and the glues, primers and other companion products they offer. Since then we have gone through many tons of the material using it in most signs and projects we tackle. This journal will chronicle our many adventures both past, present and future. I'll talk from the perspective of someone who pushes these products to the creative limit on a daily basis. I'll be adding to the stories two or three times each week. -dan

Sunday, January 23, 2011

Routing bits for texture files

A question I often hear concerns the routing bits I use for our textured projects. For most of my projects I use two cutting tools. A 3/8" ball nose bit is used to rough out most of our projects unless they are really large. Generally I use this tool with a 0.1" offset and a 50% overlap. I make as many passes as necessary, most often not taking a deeper cut than 1" per pass. 

For the detail cuts I make one final pass with a 1/8" ball nose bit. For a long while the biggest limitation on my designs was when an edge of my project was deeper than the cutting flutes on the bits. The smaller the bits, the more it limitations it imposed on my design. Then they invented the taper tools. The bit I use most often had a 1/4" shank and tapers down to the1/8" ball nose end. I can get these bits with the flutes going up the shaft up to a 1 1/2" depth. The angle of the taper is slight - only 1 degree, meaning it is not noticeable.

To get the router to make only one detailed pass I purposely enter false information when I input the tool data. I tell the machine the cutting edge is longer than the material depth. The reality is that because of the rough pass with the 3/8" bit I am seldom removing more than 0.1" of material. The only critical depth is the larger vertical areas which now can't be more than 1.5". This final pass is done with a 75 - 90% overlap depending on the final finish I want to achieve. For the material we use most often, 30 lb Precision Board, an 80% overlap is sufficient.