Rose Engines: The Preferred Machine for Guilloche

I was wonderfully shocked to discover that the short blog entry on Engine Turning, Jeweling, and Guilloche was the most viewed last week. It looks like others also find these intricate decorative machine arts as fascinating as I do. Consequently, I thought it would be great to share a few excellent videos that genuinely demonstrate how Guilloche (pronounced "Gee-o-shay") is accomplished with a device known as a "Rose Engine". It's possible that the application of the Rose Engine contributes to the use of the term "Engine Turning" for Guilloche. I’m partial to the latter term. It's more sophisticated and the concept of Engine Turning is deeply embedded in many people's mind as the small abrasive circles visible on metal. At this point, I would like to extend my apologies for not using the correct accent on the word Guilloché, but typing it without the accent is simply easier and this usage seems to be broadly accepted on the internet.

Our first video is from a fine watchmaker that hails from right here in the good old U. S. of. A.  Roland G. Murphy makes spectacular hand-crafted wrist watches, and their video is also extremely well done:

As you can see from the video, Guilloche is done with a machine that's more like a very specialized shaper than a lathe or milling machine.  This results in the markings on the material having a much different character and a lot more texture.  In addition, these old machines are entirely hand powered.  They use cams (called "Rosettes") to give the workpiece a periodic "wobble" that results in the distinctive curves and curlicues that are characteristic of Guilloche.  If you watch closely, you can see that the operator has to manually start, stop, and position the cutter to keep the design within the outline it is bounded by.

Here is another great video from the great old watch maker Vacheron Constantin:

It's a little less technical but no less fascinating to watch this fine art form being done my VC's "Master Guillocheur".  There are some great closeups showing the shaper-like tool peeling chips off of watch faces.

Here's a last one, in the spirit of fine watchmaking of the other two:

I believe this video is from Victorinox, and there are some fascinating insights to be found in it.  The discussion of how the Guillocheur uses his sense of touch and visual indication of chip size and formation to create the best effect is wonderful.  Also note that this Rose Engine has not only the normal Rosette cams, but an additional cam at right angles that he uses to create more geometric patterns.  Heretofore I had associated Guilloche primarily with curves, but we can see this is not a requirement.

Looking at these wonderful old machines, my first inclination is to dive into creating a software simulation of a Rose Engine that could be used to create g-code for a CNC.  Simulating the motions of the machine and allowing the creation of the Rosettes from perhaps DXF files would be straightforward if complex and voluminous.  It would be a fascinating project for me, but one that will have to wait a while as there are more pressing commercial realities for CNCCookbook!