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Ajohn

Bulova Precisionist Crystal Replacement

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I decided to change the battery on my Bulova myself. I did have some one else replace it last time and they mentioned that the back was very tight and a press was needed to replace the back so bought one. :whistle: Result

http://www.23hq.com/ajohnw/photo/61879075

I decided that the die at the bottom was bending so tried something more solid. I put my entire weight on the press and it still wouldn't go in before breaking the glass.

Main reason for posting is replacing the crystal and getting the stem out. For some reason I can't use the insert image from url so can only provide a link showing the inside of the watch

http://www.23hq.com/ajohnw/photo/61879068

No problem removing the white plastic movement holder but am unsure about the insulator over the movement. The watch uses a lithium coin cell. I assume the insulator can be flicked out some how and could to with a clue before having a go. Under that I expect to find something to press etc to allow the stem to be removed.

I bought a newer model of the same watch after breaking the glass. The have gone to a rather smooth second hand sweep and much prefer the older one which mimics a high quality auto's movement - :rolleyes: perfectly in my view. I might even put the movement in the newer watch. :laugh: Might  be best to make sure my new dual pillar screw jack type press can get the back on before even contemplating that.

John

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I needed to get something to keep the movement in to avoid dust getting on it so slow progress. It looks fairly well enclosed but I have had dust problems in the past from simply having the battery changed so bought one of those small bell jar like items.

The insulator just lifts off, loosely clipped in place. It sticks to anything rather easily so thought I had lost it while trying to get the stem out.

It has a press engraving plus arrow. Instructions on other watches wouldn't work. On the this one the watch crown needs to be pushed right in, not part out etc.

So now I know that the original crystal was 1.2mm thick. It fell to pieces when it came out so can't measure the diameter. It uses the usual style of "gasket" around the crystal but not sure what these are called. Also best way of determining the size? I do have a vernier caliper and but have no idea how wide a tolerance is possible on the fit.

Any suggestions ?

John

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41 minutes ago, Ajohn said:

I needed to get something to keep the movement in to avoid dust getting on it so slow progress. It looks fairly well enclosed but I have had dust problems in the past from simply having the battery changed so bought one of those small bell jar like items.

The insulator just lifts off, loosely clipped in place. It sticks to anything rather easily so thought I had lost it while trying to get the stem out.

It has a press engraving plus arrow. Instructions on other watches wouldn't work. On the this one the watch crown needs to be pushed right in, not part out etc.

So now I know that the original crystal was 1.2mm thick. It fell to pieces when it came out so can't measure the diameter. It uses the usual style of "gasket" around the crystal but not sure what these are called. Also best way of determining the size? I do have a vernier caliper and but have no idea how wide a tolerance is possible on the fit.

Any suggestions ?

John

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If the gasket is ok measure the internal diameter with the gasket in place between 6&12 and 3&9 just to be sure, then i would order the diameter of the reading and also order the next size up as they are less than a couple of quid each . Thats what i do anyway 

Cheers 

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I can't measure the inside dia of the gasket as the glass has deformed it so took it out. The recess is 35.2mm dia by 1.07mm deep. The gasket is 1mm deep and 0.44 - 0.45mm thick. Glass was 1.2mm thick.

Cousins list some 1.3mm glasses but the gasket seems to be a problem. They may have misdescribed a 35.5 o/d by 1mm deep in the ISO range as they list 2 at 0.8 deep and one at 1.2 but could just be different thicknesses. I don't know but 0.3mm over size seems a bit much to me. It wasn't easy to get the old one out so reuse is dubious.

1.3mm glass if there is a suitable dia should be ok but not at all sure about sizing the gasket and dia glass to go with it.

John

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18 hours ago, Ajohn said:

I can't measure the inside dia of the gasket as the glass has deformed it so took it out. The recess is 35.2mm dia by 1.07mm deep. The gasket is 1mm deep and 0.44 - 0.45mm thick. Glass was 1.2mm thick.

Cousins list some 1.3mm glasses but the gasket seems to be a problem. They may have misdescribed a 35.5 o/d by 1mm deep in the ISO range as they list 2 at 0.8 deep and one at 1.2 but could just be different thicknesses. I don't know but 0.3mm over size seems a bit much to me. It wasn't easy to get the old one out so reuse is dubious.

1.3mm glass if there is a suitable dia should be ok but not at all sure about sizing the gasket and dia glass to go with it.

John

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Cousins do do some sternkreuz glasses with an i gasket but not in 35.5 or 1.3mm unfortunately , I think you will have to buy the glass and gasket separately , they do a 35mm in 1,3mm and they do the gaskets separately , our resident watchmaker @simon2 is going to be the best man to advise on this , or carry out the repair

cheers Andy

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Cousins show a 35.3 - 34.5mm gasket but 1.3mm deep and glasses either side of 34.5. So ordered the gaskets and 3 glasses 34.4 to 34.6. All Cousins own so hope quality is ok.

The gaskets come in pairs so I may try trimming down with a razor blade after fitting. Hope 35.3 will go in. Some web sources suggest a bit oversized is ok but I have my doubts. :shothead:At leasts the glasses may be ok if I can find the correct size of gasket.

John

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Haven't put it all back together yet but looking ok. The gasket went in pretty easily. It may be more apparent than the original one. Pressed the glass in having decided to try the 34.5 as it looked like it would be a tight fit. Maybe the gaskets allow for compression. Moderate pressure with my thumbs doesn't move it ;) but don't know how hard to press.

The excess gasket depth was pretty obvious so used a fresh safety razor blade at near 45 degrees to trim it off. Sort of 35 degrees plus. Tends to slip off at lower angles so had to redo it in a couple of places. Best to rotate the watch and it needs a bit of pressure on the blade.

:cool: Then wiped my finger prints off the glass with IPA. Yet to look and see just how well that has worked.

John

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