Jump to content

Choosing the correct replacement crown?


Recommended Posts

My latest project watch is a BFG 866, which states that it is (was) waterproof to 5atm. 

I have a stem but am missing the crown, there is no threaded tube on the case, so its not a screw down crown, but I’m struggling to find the right replacement.

The stem is 1mm diameter, the opening in the case is 2.5mm and I believe the crown should be 5mm. 

I assume the crown should have a tube with a rubber seal of some kind.....?

Am I best buying one of those cheapo eBay jobbies with assorted crowns?

4D5F9EBF-F1E6-4B93-A13A-CB49E21813DC.thumb.jpeg.6a44fe484d2a5283e04cafeb4dc8d3e6.jpeg

Edited by Robbie010
Link to comment
Share on other sites

29 minutes ago, Robbie010 said:

The stem is 1mm diameter, the opening in the case is 2.5mm and I believe the crown should be 5mm. 

Your watch has no pendant tube, so I don't see how it can be water resistant, unless you fit one. Beside that a pendant tube is needed to avoid the crown wobble and the stem bend easily. The tube is measured on the ouside diameter, to match the seal on the crown.

Quote

I assume the crown should have a tube with a rubber seal of some kind.....?

Yes, so called waterproof, Swiss style. 

Quote

Am I best buying one of those cheapo eBay jobbies with assorted crowns?

All assortments are very useful especially you intend to do a lot of resturations on watches that match the boxes you have. And having the right part ready to fit is a great achievement.  Look the table which lists the sizes, see if there's what you need before buying.

Otherwise Cousins has a good selection of individual crowns also.

  • Like 3
Link to comment
Share on other sites

Press-fit a pendant tube in that hole, there's a special tool for this. That's going to leave you with a pendant tube OD of 2.5mm. The crown fits over this to form a waterproof with a rubber seal inside the body of the crown. You have chosen 5.0mm crown diameter, you still need to know the tap size (metric diameter of the threads on the winding stem, commonly 0.9 but also other sizes). Those 3 numbers, plus the finish (stainless, gold, etc) and the type (waterproof, swiss style, domed, etc ) will find you a crown.

Older, cheaper, non-waterproof watches just have a hole with no pendant tube and no seal, or sometimes a notch in the case rather than a hole, so the movement with stem fits into the case and a press-on caseback holds the movement and stem in place (often seen in "ladies" cocktail bracelet watches)

 

  • Like 1
Link to comment
Share on other sites

On 1/16/2021 at 7:14 PM, KOwatch said:

Press-fit a pendant tube in that hole, there's a special tool for this. That's going to leave you with a pendant tube OD of 2.5mm. The crown fits over this to form a waterproof with a rubber seal inside the body of the crown. You have chosen 5.0mm crown diameter, you still need to know the tap size (metric diameter of the threads on the winding stem, commonly 0.9 but also other sizes). Those 3 numbers, plus the finish (stainless, gold, etc) and the type (waterproof, swiss style, domed, etc ) will find you a crown.

Older, cheaper, non-waterproof watches just have a hole with no pendant tube and no seal, or sometimes a notch in the case rather than a hole, so the movement with stem fits into the case and a press-on caseback holds the movement and stem in place (often seen in "ladies" cocktail bracelet watches)

 

Sorry to resurrect this thread but I’m still struggling to get my head around this and I suppose there is no point in me not getting to the bottom of my query while I’m trying to learn.......

My new Vernier Calipers arrived today so I measured the stem, which was 1.1mm. Now, this is the outer width of the thread so I assume the stem thread is actually 1mm. 

The case does not have a pendent tube fitted and you advise that I fit one - does that mean that the case would have originally had a tube fitted that has been removed?

If that is the case, once I have fitted a pendant tube should I use a crown with a tube or without a tube?

Also, if the watch case never had a pendent tube fitted, which type of crown would have originally been installed?.

Thanks. 

Edited by Robbie010
Link to comment
Share on other sites

15 hours ago, Robbie010 said:

If that is the case, once I have fitted a pendant tube should I use a crown with a tube or without a tube?

In horology terms, crowns do not have a tube, but can have a shorter or longer pipe. That is the part where the stems screws into.

Quote

Also, if the watch case never had a pendent tube fitted, which type of crown would have originally been installed?.

Maybe one with a pipe long and wide enough to stay always in good contact with the case hole, to minimize wobbling.

Link to comment
Share on other sites

CousinsUK:

11 x Ø4.50mm x Ø2.50mm, SS

C528GZ1

 

1.1mm is a thread size. It's possible it didn't have a case tube, but it wouldn't have been water resistant.

Hard to tell from the photo but the caseback looks like a screw-on so decent WR is possible . How's the gasket? Definitely want to have  a look at that crystal also.

Edited by KOwatch
more info
Link to comment
Share on other sites

18 minutes ago, Robbie010 said:

Is there any way of fitting a pendent tube / case tube without having to fork out £130 on the Horotec tool from Cousins??

As long you can find a way to press down straight it will be fine. Normally watchmakers have some sort of press that they adapt for various uses. Also consider if the watch you work on is worth to invest in new tools and which chances are of needing them again.

The Chines makes copies of various expensive tools

https://www.aliexpress.com/item/10000014322393.html

Link to comment
Share on other sites



  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • 🤔 leaving the EU meant that UK was no longer part of the convention and have already been turned down an independent reapplication. I'm pretty sure courts have to be held in Switzerland in this case. There will be a lot more watches stashed away in draws  tbh, folk wont be able to afford to maintain them. Cheap watches will be bought and top end watches by folk with plenty of cash that can pay for service and repair. The expensive once in a lifetime gifts and everything else inbetween will be at the forgotton when they stop working. I know i was being a numpty, get used to it 😄 Anybody that knows will boycott them, but besides repairers who will know. Nope will never buy one, i made that decision as soon as i learnt about this. 
    • although not in this case.  It was the Lugano Convention and its deficiencies that allowed a Swiss court decision in the first place.  This isnt really a Brexit issue at all.  A decision that affects both the EU and the UK should never have been heard in Switzerland. I bet the authorised service centres in the UK are pretty pleased.  It's a massive shame, though; I believe watch owners should be able to choose to have their watch serviced by whoever they trust.
    • Hi guys I think that old hippy is correct, it opens the gates for china to manufacture aftermarket spare parts. considering that they already do work on behalf of the Swiss I guess this decision gives the a little more legitimacy to tool up and I am sure they will take advantage of the situation either with or without the blessing of the Swiss watch industry  Having read about the protectionist machinations of the Swiss in the history of Europe they were the only ones to get fat at everybody else’s expense. I think the outcome could have been guessed at but ,  fair play to Cousins UK for standing up to them.  Now the question,  will everybody boycott Swiss watches and Swatch, no way they will still fill their coffers.  Me I stick with the Japanese once renowned for cheap shitty watches who came good through industrial effort and don’t for get the Russians that most dismiss as low grade crap. Wouldn’t buy a swatch product ever how about you all.? a
×
×
  • Create New...