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Discussion Starter · #1 ·
Can anyone help with this problem please.
I bought a job lot of Bell-matics and have started to re-build and renovate them.
Some have the thinner pendant tube where the crown seal fits over the tube and some have the larger pendant tube where the crown seal fits inside the tube.
Bought one of each type from Cousins and neither fit the winding stems as the stem is too large.
I measured the stem as 0.93mm dia. which would suggest it is a 1mm dia. which as far as I can see is a "Tap 9" size.
Throughout the Cousins crown section, they list Tap 9 as 0.9mm. Is this completely wrong, should 0.9mm not be Tap 10 ?
Are all Bell-matic winding stems a 1mm thread, I.E Tap 9 ?
Any guidance would be appreciated

Archmill
 

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Got a link to what you bought? Cousins seems to do tap nomenclature differently than what I’m used to in the US (where tap 10=.9mm). Cousins calls .9mm a tap 9, and 1.00mm a tap 10, etc. While their system is more straightforward (tap number equates to nominal measurement), it confuses things as the other system seems historically prevelant elsewhere.
 

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Discussion Starter · #3 ·
Got a link to what you bought? Cousins seems to do tap nomenclature differently than what I’m used to in the US (where tap 10=.9mm). Cousins calls .9mm a tap 9, and 1.00mm a tap 10, etc. While their system is more straightforward (tap number equates to nominal measurement), it confuses things as the other system seems historically prevelant elsewhere.
Thanks for the reply Noah, got the reference number 55M06NN1 off E-bay, put it into Cousins site and here's what I found :- https://www.cousinsuk.com/sku/details/search-seiko-case-parts/s15137
Crown fits the case perfectly but not the winding stem. seems to be a 1mm stem and a 0.9mm crown.

Archmill
 

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What case number are you installing the crown on? For the stem thread OD, are you using a micrometer to measure to the nearest hundredths? I don’t think I’ve got that crown in stock so I can’t tell you what it is actually measuring. Maybe try a more modern stem from another watchwhich likely has a .90mm thread to confirm that your new crown is indeed a .90 thread.
 

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Discussion Starter · #6 ·
Might have sorted this out. I took Noah R's advice and looked at a stem and crown from a fake Seiko, the kind from the "looky, looky man at the beach" and no I didn't buy it. The crown does not fit the bell-matic stem but the stem does fit the Cousins crowns. The stem is 0.8mm.
Measured the Bell-matic stem with the crown off with digital calipers and it is 0.9mm.
One of the Bell-matic stems has an stem extension which as it turns out, is a 0.9mm (stem side) to 0.8mm (crown side) and hey presto the Cousins crowns fit.
So to sum up, looks like the Bell-matic stems are 0.9mm (part No. 354805) and the Cousins crowns are 0.8mm so I will buy a set of taps and re-tap them. The watch I am working on just now is a 4006-7029.
Grammarofdesi, how much for the stems and whereabouts are you ?

Archmill
 
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