Rolexman Posted June 3, 2009 Report Share Posted June 3, 2009 I looked at some webshops but there are so many different main springs to choose from and I have no idea what all the numbers and abbreviatons mean e.g. strength I was hoping someone could help me out. I'm working on a vintage watch which is over 40 years old and belonged to my grandfather. I can't pin point the movement based on the markings (maybe someone else can?). It's a 21j hand wind movement which looks and disassembles simular to an ETA 6497. It's only smaler and I don't think it's Swiss. The main spring meassured a little more than 30 cm in lengt and aprox. is 1mm wide. The barrel has an inner diameter of aprox. 4mm. I'm scared if I buy the wrong one the strength might damage the gear train..... So if you have any tips ore suggestions, they are very welcome Quote Link to comment Share on other sites More sharing options...
RWG Technical Posted June 3, 2009 Report Share Posted June 3, 2009 Measure the mainspring dimensions, length, width and thickness with digital calipers. You need 1/100 mm accuracy. Any good supply house should be able to match those dimensions to the Dennison tables and provide a replacement spring. Mention the speed of the movement as well and this helps with selection, ie 18,000 BPH, 19,800 BPH etc... Quote Link to comment Share on other sites More sharing options...
Rolexman Posted June 3, 2009 Author Report Share Posted June 3, 2009 Measure the mainspring dimensions, length, width and thickness with digital calipers. You need 1/100 mm accuracy. Any good supply house should be able to match those dimensions to the Dennison tables and provide a replacement spring. Mention the speed of the movement as well and this helps with selection, ie 18,000 BPH, 19,800 BPH etc... Thanks Zig! For Dennison I need to measure strength. Also the original spring was broken and disformed so measuring it opposes a difficulty Quote Link to comment Share on other sites More sharing options...
RWG Technical Posted June 3, 2009 Report Share Posted June 3, 2009 I think the thickness should be directly related to the Dennison strength...not positive though. More info: The marking is for a OTERO factory movement, this may help in the parts selection. Quote Link to comment Share on other sites More sharing options...
POTR Posted June 3, 2009 Report Share Posted June 3, 2009 Dugena 2205 == Otero 74 18000 BPH Quote Link to comment Share on other sites More sharing options...
Rolexman Posted June 3, 2009 Author Report Share Posted June 3, 2009 Thanks guys! You just made my day. Odering has never been so easy REALLY REALLY appreciate it. Mark. Quote Link to comment Share on other sites More sharing options...
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