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Cannon pinion slipping?

Simeon
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Simeon WRT Addict

Simeon

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I have a Tissot Seastar with a Cal 794 movement that I serviced. I have got good amplitude of about 280 degrees DU and DD with a full wind and a consistent rate of about -10 secs per day in horizontal and vertical positions. I have found that when wearing it keeps good time for most of 24 hours and then at one point I will look at it and all of a sudden it will be 20-30 minutes slow. 

I am guessing that this is a sign of the cannon pinion slipping. Could this be due to additional drag due to the date / day wheel changing because it doesn't slip all the time?

Setting the time, feels quite 'loose' so this is a typical sign of the cannon pinion needing to be tightened. I can't feel any additional resistance due to the calendar works changing over, so not sure if that is overly tight and providing too much resistance to the train that results in the cannon pinion slipping early. 

I don't have any dedicated cannon pinion tools so I was intending to just give it a slight nip with some electronic side cutters while still installed on the centre wheel pinion to prevent it crushing. Any problems with that (beyond the obvious of cutting straight through the cannon pinion and centre wheel 😜)?

I could always just buy a new cannon pinion but if I can repair my own that must be better. 

Neverenoughwatches Distinguished Member

Neverenoughwatches

Posted
Posted
11 minutes ago, Simeon said:

I have a Tissot Seastar with a Cal 794 movement that I serviced. I have got good amplitude of about 280 degrees DU and DD with a full wind and a consistent rate of about -10 secs per day in horizontal and vertical positions. I have found that when wearing it keeps good time for most of 24 hours and then at one point I will look at it and all of a sudden it will be 20-30 minutes slow. 

I am guessing that this is a sign of the cannon pinion slipping. Could this be due to additional drag due to the date / day wheel changing because it doesn't slip all the time?

Setting the time, feels quite 'loose' so this is a typical sign of the cannon pinion needing to be tightened. I can't feel any additional resistance due to the calendar works changing over, so not sure if that is overly tight and providing too much resistance to the train that results in the cannon pinion slipping early. 

I don't have any dedicated cannon pinion tools so I was intending to just give it a slight nip with some electronic side cutters while still installed on the centre wheel pinion to prevent it crushing. Any problems with that (beyond the obvious of cutting straight through the cannon pinion and centre wheel 😜)?

I could always just buy a new cannon pinion but if I can repair my own that must be better. 

Insert a brass rod or copper wire. And nail clippers with and adjustable depth stop

  • Like 1
nevenbekriev Distinguished Member

nevenbekriev

Posted
Posted
3 hours ago, Simeon said:

 I was intending to just give it a slight nip with some electronic side cutters while still installed on the centre wheel pinion to prevent it crushing. Any problems with that (beyond the obvious of cutting straight through the cannon pinion and centre wheel 😜)?

This is wrong! Never try to tighten the cannon until it is in place on the center wheel! First - the cannon will not get tightened if the thing inside has no some free play, and second - the pivot of the center wheel (especially if it is a tube) can get deformed and thus the cannon pinion will have different friction resistance depending on it's position. It may get loose  in some positions and to tight in others.

  • Like 1
mikepilk Distinguished Member

mikepilk

Posted
Posted
4 hours ago, Neverenoughwatches said:

Insert a brass rod or copper wire. And nail clippers with and adjustable depth stop

I find broaches work well for this.

  • Like 2
Simeon WRT Addict

Simeon

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Posted
2 hours ago, nevenbekriev said:

This is wrong! Never try to tighten the cannon until it is in place on the center wheel! First - the cannon will not get tightened if the thing inside has no some free play, and second - the pivot of the center wheel (especially if it is a tube) can get deformed and thus the cannon pinion will have different friction resistance depending on it's position. It may get loose  in some positions and to tight in others.

Gotcha. I am going to push it along a smoothing broach until it comes to a stop and then lightly nip the cannon pinion against the broach at the site if the existing dents. I will then try it back on the centre wheel, where I am looking for a clean snap into position(?)

What else can I do to determine if this has been a success (or failure)?

I guess if I can't get it installed past the dent = failure.

I also guess feeling significant loose and tight spots when setting the time would be a failure as well. 

Neverenoughwatches Distinguished Member

Neverenoughwatches

Posted
Posted
2 minutes ago, Simeon said:

Gotcha. I am going to push it along a smoothing broach until it comes to a stop and then lightly nip the cannon pinion against the broach at the site if the existing dents. I will then try it back on the centre wheel, where I am looking for a clean snap into position(?)

What else can I do to determine if this has been a success (or failure)?

I guess if I can't get it installed past the dent = failure.

I also guess feeling significant loose and tight spots when setting the time would be a failure as well. 

Determine by feeling the friction through the crown on time setting. Broaches will be soft enough to work, save it for just this task. Take it light and if you overshoot with too much hammer the broach out. Needless to say on your first attempts with this take it steady.

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