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Tokunaga on: 150m diver's watches (crystals) of 61 cal. and 63 cal.

8427 Views 3 Replies 4 Participants Last post by  Jellyuddles
Authored by Tokunaga


Dear Mr Ikuo Tokunaga - San

I am a member of the Seiko and Citizen Forum.
A few of us are trying to get a Sapphire Crystal manufactured to fit on both the 6105 and 6309 diver watches.
To enable this we need the dimensions of the crystal, including the details of the bevelled edge.

Can you help?

Here is a link to a thread on the forum which explains what we are trying to achieve:

I am happy for you to respond in public, on the forum if you wish.

Many Thanks and Kind Regards



Dear Antz-san and other forumers,

The outer diameter size of both glasses on 150m diver's watches of 61 cal. and 63 cal. are same as just 32.00mm, and the glass gasket (code: EC3160) and the glass fixing ring (code: 83338969) are also same, so the common use of the glass may be able to be carried out.

The cross section of 150m diver's watch of 63 cal. was introduced on the S&C forum before. [ ]
Managing the dimensions is easy for glass in flat form, but in case of 61 cal. 150m diver's watches, as shown in the cross section drawing below, managing the dimensions seems to be troublesome due to the curved form glass.

In comparison of the position of the glass bottom, that of 61 cal. is set to 0.86mm under than that of 63 cal. For this reason, if the flat glass (code: 320W34) of 63 cal. is constructed on 61 cal., it will interfere with the second hand, and the watch will stop. Conversely, if the curved glass (code: 320W26) of 61 cal. is constructed in 63 cal., the glass jumps out about 1 mm and becomes thick, but there are no functional abnormalities. So, it will be OK if the glass of 61cal. is described by drawings.

You probably know that the cost will become extremely high if you will make a small number of the sapphire glass newly. Some points on selecting a glass from among the existing glass will be described here, so even in case you will choose the glass which can be used on these watches from among the existing glass, you can refer to this, as well. OK, please see the drawing below.

First, the length of the minute hand from the center is maximum of 12.5mm, so it forms the circle which has the diameter of 25.0mm(D2) in the space. And the length of the second hand from the center is maximum of 11.0mm, so it forms the circle which has the diameter of 22.0mm(D3) in the space. For the reason of not interfering with the minute hand and the second hand, the clearance larger than 0.6 mm (original: 0.76mm) is recommended between the glass and each of those two hands. (red line)

For realizing the clearance, the dimension(H1) requires the height larger than 0.5mm (original: 0.66mm) from the glass bottom, and the dimension(H2) requires the height larger than 0.82mm (original: 0.98mm) from the glass bottom. The glass forms from a curved line which goes through these two points. It is all right about the point of the watch movement if a new glass has those sizes.

Next, as the dimensions related to a water resistant guarantee, the height(H3) of the cylinder part of the outer diameter(D1) is 1.30mm, and the angle(theta) to the upper surface slope of the glass from the cylinder end portion is from 30 degrees (61 cal.) to 45 degrees (63 cal.), and the chamfering (C) on the edge of the glass bottom is about 0.2mm. The glass fixing ring has the function of holding the above-mentioned upper surface slope of the glass [between 1.56mm (61 cal.) and 1.45mm (63 cal.) height(H4) from the glass bottom] by the path end portion of the inner diameter of 31.70mm(D4).

If the sizes of outer diameter and the mentioned portions above are same, you will be able to get or make the compatible sapphire glass with other shapes and dimensions.

I hope your dreams come true.


Ikuo Tokunaga

Ikuo Tokunaga

Picture credit: Seiko
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missing photos

does anyone have means of obtaining (perhaps re-posting) this information to include the drawings/photos which originally accompanied the text, yet currently do not appear? note I would like to submit the detailed measurements (including photos) to a watch crystal mfr in hopes of having one custom fabricated for my 6105-8119.

many thanks in advance for the assistance.
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