Part 1: Machining plató (bridge side)

6 Comments 19.03.2015

movement plató/baseplate (bridge side)In this first lesson we will produce watch plató. Plató (or plate, platine, baseplate etc.) is an essential part of watch movement – it is used as a base for all moveable parts. The material for the plató is used, in general, non-ferous and non-magnetic metal alloy: a copper alloy (some kind of yellow brass, silver brass like neusilber/pakfong) or precious metal (gold, silver, platinum) alloy. Now in the modern age some watchmakers or producers are also trying to use an artificial materials. Because we are all amateur watchmakers, we will go back to the roots and we use the standard material – a yellow brass that means “Copper-Zinc-Lead alloy” or “Leaded brass”. I choose a free-cutting brass CuZn36Pb3 (CW603N/C36000) but clock-brass CuZn39Pb2 (CW612N/C37700) is a good choice too.

The basic rule for selecting a brass for machining is: “Harder is better”. Most suppliers of brass products offering a sheets or rods in hardness HARD or DOUBLE HARD and it’s exactly what we need.

It’s possible that you will have a problem buy that material in a small amount. In this case, you can use the easy-to-find brass CuZn37 (CW508L/C27200) which is available in any model shop.

All the procedures below described apply to my work on my own CNC mill, lathe and other machines. Different working procedures may be required in your specific case. The text, diagrams and the video are provided as a simple tutorial only. It is expected that you know what you do and the way you do it. Anything you do is your own responsibility; I shall not be liable for any losses occured by your work to you or other persons and/or on property.

And now the most important thing – tools. If you want to get seriously in a precision manufacturing and mainly in a watchmaking, don’t use a junk tools (end mills, drills, cutting tools etc.) sold in on ebay especially. Trust me, when you buy a tools from the good and verified suppliers, your work will be amazing. I know that a quality tools are expensive. But think – they are LITTLE MORE expensive as a inferior tools, but they are MUCH MORE durable, more precisely and generally much better.
movement plató/baseplate (bridge side)
Here is the list of necessary tools that we use in this work practice:

  • A: Carbide spotting drill 120°
  • B: Drill OD = 0.45 mm
  • C: Drill OD = 0.75 mm
  • D: Carbide end mill OD = 3.00 mm
  • E: Carbide end mill OD = 2.00 mm
  • F: Drill OD = 1.45 mm
  • G: Drill OD = 1.95 mm
  • H: Drill OD = 2.95 mm
  • I: Carbide end mill OD = 0.40 mm
  • J: HSS end mill OD = 2.00 mm
  • K: Chamfering tool 120°

At the beginning we will need a brass prism (or strip) in width 40 mm, height around 65 mm and thickness at least 3 mm. Because we will to drill throught, a good idea is add a pad under a brass strip – aluminium sheet is good enough.

In this step you don’t have to deal with if it’s a squared and parallel piece of brass. Correct height and parallelism we will setting in the next step – by machining under side.

The final product should look like this – 3D model:
movement plató/baseplate (bridge side)
And here is the result after machining:
movement plató/baseplate (bridge side)
The technology used to manufacture a plató is CNC milling. If you not own or you don’t have access to CNC mill, you can try to use a lathe for production. How it’s made with lathe you can see in this video.

For better understanding every step of the production I’m prepared a short video. Complete manufacturing process is described with appropriate tool.

I will not describe the specifically technological settings of mill or tools such revo, feeds, Ap etc. It’s because I assume that you known your machine, its possibilities and capabilities. Also all about manufacturing conditions of the tools you can find in their datasheet or in producer’s catalogue.

You can download 3D model (.stl format), 2D drawing (.dxf format) and simple drawing of the watch movement plató here (only registered users can download CAD files):

movement plató/baseplate (bridge side)
Only registered users can download this file
movement plató/baseplate (bridge side)
Only registered users can download this file

If you need CAD files in other format it’s possible to make it, but keep in mind that it will be a little problem for me due to the software limitatons… So try to use pre-prepared format please :)

Image gallery with detailed pictures of a few steps of the movement production:

I hope that all procedures in this lesson was clear and obvious for you. If you still have any question about this step use comments below. I will try to answer every RELEVANT question as soon as possible.

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  1. timothy psaledakis

    Can you share what CNC milling machines you’ve seen handle the level of accuracy needed for watch part manufacture? On todays market, how expensive are such machines? I’m considering production via CNC machine with hand finishing and engraving, a combination of old and new techniques….
    Any words you could share would be greatly appreciated!
    Sincerely, Tim

    1. Patrik 'Robur' Štábel

      the required accuracy for making a small parts is just 0.01 mm and less, but the important thing is the precision for repeatability especially when you use more tools.
      On the market today you can find matching machines ranging from 2.000€ (cheap Chinese) to 150.000€ (Aciera, Datron etc)…
      But the best way IMHO is to make your own machine as I do. When using quality parts and control system then the price will be less than 10.000€ and quality and productivity will be “extremely perfect” :)
      First test run of my machine you can see here:

  2. Cris SfoCris Sfo

    Hi Patrik
    I know that you can have difficulties, but I believe that you also use SolidWorks so if you can bring in download the file in .SLDPRT or .SLDASM would be great!
    if you have problems do not worry, I will invent something myself! :)
    In any case, you’re great!
    good job!

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