When was the CAD model made?

It was made between mid-February 2020 and the beginning of May 2020.

Where can I get the CAD model?

It is available at github

How was the CAD model made?

Drafts were made on paper and the survey data was transcribed, 359 parts were designed and carefully assembled.

Why was the CAD model made?

Initially I did not have any plans to make a CAD model. The idea only occurred to me around February 2020. At that time there was a vague project by a Paris association to construct a model, but no one from that association had the actual data, and moreover the members of that association were not open for equal cooperation with researchers. One clock repairer (sorry, I hate to say watchmaker or clock maker for people who don't make watches or clocks) was even very convincing that he would construct the model. But that was because mid-2019 some people (not me!) thought that the Trinity church clock was identical to the Notre-Dame clock, which is not true.

Anyway, at the beginning of 2020, I felt more and more the duty to provide my data and contribute to the reconstruction effort, and I also wanted to prove that there is no need to be a clock or watch repairer to do such a work. Research and study of clocks is an activity different from that of repairing or cleaning clocks and watches, and it involves quite different skills. Repairing clocks does not make oneself a researcher or a historian in horology.

My first idea was to team with someone who had some experience with CAD modelling and provide him with handmade drafts. But this proved very cumbersome, and eventually I took up the project myself, which I made public in early May 2020.

Am I a watch/clock repairer/maker?

No, I am not. I am a scientist, working in the history of technology and computing. I do not even own clocks! But among many other things, I survey and study clocks, in an effort to document and preserve our industrial heritage. Clocks are not a hobby of mine.

When was the application made?

My Android application was mostly made in January-March 2021. That of my students was made between November 2020 and March 2021, based on my CAD files, as well as on an initial stub. The two applications are pretty much independent and none really influenced the other.

Is the model functional?

The going work is pretty functional, as can be seen in the animations. However, some slight adjustments may be needed in the striking works for them to work perfectly. These are currently shown still, and the trigger lever has been removed, as it was on the clock when I examined it. The striking works might be made to work in a future version. Any person fluent in CAD should be able to get these works working.

How accurate is the CAD model?

I took a number of measurements during the 2016 examination of the clock, including teeth counts. The teeth counts of the model should be accurate, except for the small transmission bevel gears, where the actual teeth counts are smaller (but that can be improved in a future version). A number of other dimensions have been measured and the rest was inferred from photographs, as well as from comparisons with two very close (but not identical clocks), namely those of the Saint Augustine and Trinity Churches in Paris. These clocks were first surveyed by me in 2017 and 2018.

All in all, distances between arbors should be pretty accurate, usually to 1-2mm. Some other dimensions may be in error by 1 or 2cm.

Screws, holes, etc., have not been measured, and most screws have not been modeled. But if needed, most of the dimensions can be taken on the Trinity or Saint Augustine clocks.

Some elements have slightly been simplified, but might be improved in the future. There are some other known problems, which might be fixed in the future.