Venus Chrono Mainspring compatibility question

Discussion in 'Watch Repair' started by deloid, Apr 13, 2017.

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  1. deloid

    deloid Registered User

    Nov 30, 2002
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    I'm working on a Venus 165 Chronograph in need of a new mainspring. One of my references states that it uses the same mainspring as the Venus 150 (base mvt).

    I have a Venus 150 parts mvt so I took out both barrels and compared the springs and they are slightly different (1.3mm thick versus 1.6mm thick). They are of the same strength. I think the 1.3 was an old replaced spring that was simply incorrect.

    The barrels are the same diameter but one barrel is .02mm thicker than the other. Both springs will fit into both barrels.

    Now I have two problems:
    1 What spring size fits the Venus 165?
    2. In the process of measuring and remeasuring the springs and barrels I think I may have mixed up the barrels even though I tried to be deliberate with their location (separate storage). I suspect they are still compatible but would prefer to know which belongs to the 150 & 165.

    Thanks for your help.
     
  2. Accutronica

    Accutronica Registered User

    Nov 21, 2016
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    If their thicknesses are different then their strength is different. You need to get some small tins with glass or plastic lids to keep parts in so that you can keep better separation of them without mixing them up. I don't know anything about Venus Chronograph's so I can't help you there.

    Robert
     
  3. deloid

    deloid Registered User

    Nov 30, 2002
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    Accutronica, Sorry I confused you with the incorrect terminology I meant the heights were 1.3mm and 1.6 mm. The strengths (thickness) are the same at .13mm.
    I do use watch parts containers with covers for all the watches I am working on. My error was a loss of concentration and work method...probably from the frustration of discovering the mainsprings were different.
    Thanks for pointing these problems out though.
     
  4. Accutronica

    Accutronica Registered User

    Nov 21, 2016
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    Lol! I should have caught it - a mainspring 1.3mm thick would be way to strong for a watch.
    It's not hard to mix things up especially the smaller they get. Concerning mainsprings, I would use my markers and put a red/blue/black dot on one, and a different color dot on the other writing down which color is for which watch. You can do that with barrels also.
     
  5. karlmansson

    karlmansson Registered User

    Apr 20, 2013
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  6. deloid

    deloid Registered User

    Nov 30, 2002
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    An excellent response from Dushan Grujich that I'll add here for future reference:

    "Venus 150 (152) mainspring, according to its data sheet, is 1.60 x 0.125
    x 400 corresponds to GR book mainspring #4555 1.60 x 0.125 x 400 x 11.5,
    while
    Venus 165 (166) mainspring, according toGR book is #4532 1.60 x 0.115 x
    440 x 11.5
    Venus 150 data sheet:
    http://www.geocities.ws/dushang2000/Downloads/Venus 150.pdf

    Knowing that the original Venus mainsprings were most likely produced by
    Generale Ressorts, then data from their catalogue would be more
    trustworthy than data from some other (unnamed) source.

    Incidentally, difference in strength i.e. thickness of 0.015 mm of the
    two mainsprings is huge, simply as the ratio is inverse of the third
    power, so the two cannot be interchanged without getting into problems.
    Unless of course the intention is to overcome all the losses in not so
    professionally serviced watch movement."
     
  7. karlmansson

    karlmansson Registered User

    Apr 20, 2013
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    Seems legit.

    Not sure if Ranfft is the "unnamed source". I'm not sure where he gets his numbers but his database is pretty comprehensive.

    I've worked with a couple Venus models, 170 and 140, but I've never seen the 165. Did you work out if it is really derived from the 150? Because the same base movement would suggest the use of the same mainspring, right?
     
  8. deloid

    deloid Registered User

    Nov 30, 2002
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    I have catalogs that indicate that the Venus 150 mainspring is the same as the 165 and...others that don't list the 165 or have a longer weaker spring. I do know the barrels and arbors are different (slightly). Many of the other 165 parts are interchangeable with the 150. This makes working on this rare caliber easier (have a scrap 150 mvt).
     
  9. Bila

    Bila Registered User

    Jan 22, 2010
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    All my sources indicate the 150 is the same as the 165, Dennison size 7-9-17 or you can use 7-9 1/2-17
     
  10. deloid

    deloid Registered User

    Nov 30, 2002
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    Dushan stated this:
    Knowing that the original Venus mainsprings were most likely produced by
    Generale Ressorts, then data from their catalogue would be more
    trustworthy than data from some other (unnamed) source."

    This is a more reliable source than the others I have that also(on some) state that the 150& 165 mainsprings are the same. Unfortunately even the listings for the venus 150 are quite different as listed in my sources. Different enough to create an immediate or future problem with the watch. I trust what Dushan wrote and what Cousins sells.
     
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