by Curtis D. Thomson - March 2007
While at first this question may seem like a head scratcher - a dial is a dial is a dial - it does in fact make sense, as the McGonigles' dial is anything but traditional. Having put much thought into the technical and aesthetic execution of their tourbillon movement, it was decided the dial should not hinder the owners view - not only the view of the tourbillon but the entire movement.
Safely securing the movement and enabling it to be fitted to a larger case than its "natural" diameter would allow is a case ring's standard job. The clever bit here is they have turned the case ring into part of the dial. Drilling blind holes (holes that don't go completly through the material being drilled) into the case ring for the minute marks 25, 30 and 35, 60, it also serves to hold and position the second part of the dial, a uniquely machined sapphire disc.
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In addition to the "pocket" created by the case ring, that prevents the dial from moving side to side, there is an additional measure to keep the dial in place. An O-ring is positioned in such a way under the front bezel that when it is screwed into place on the case's main body or frame, the sapphire dial is smartly held fast by the O-ring.
click the pics for more details
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*For more reference material please click Here
What Is It?
Last December I spent a Saturday with the Irish watchmakers, John and Stephen McGonigle. John, who is based in Ireland, happened to be visiting Stephen's Neuchatel, Switzerland workshop (a farily regular event - one of the brothers visiting the others workshop), which provided me the opportunity to investigate what seems to be a straight forward subject, but is, in fact, something of some confusion. "What is going on with the McGonigle's dial?"
Details
The movement is made from German Silver, with the plates having perlaged recesses, and circular graining emanating in concentric circles from the tourbillon carriage. The plates and bridges are untreated, save the barrel bridge which has been plated in ruthenium or black chrome to provide the necessary contrast for the sapphire dial. Made in two parts, the first is a clever two-in-one use of the case ring. Machined from German Silver and plated in ruthenium or black chrome, depending on the case material (gold or platinum) and/or their clients wishes, the case ring is a nice piece of engineering design itself.
Machined to mimic the shape of the barrel bridge, the sapphire dial has eight blind holes drilled for the minute marks (5, 10, 15, 20 and 40, 45, 50, 55). The given dimensions between the diameter of the blind holes and their position to the dial's edge is critical in preventing the sapphire from cracking. The writing is applied on top the dial and the blind holes (sapphire disc and case ring) are filled using the same medium.
With the movement surrounded by the case ring and the sapphire dial in place, the case and movement are fitted together. The front bezel is secured with eight screws from the inside of the case frame completing the dial assembly. The case back is then attached with eight screws - the total package yields 3 atmospheres of water resistance.
