Unfortunately not, haven't gotten ahold of one to see what it would take to make some of them.
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Why the CHS GMT movements are failing
- Thread starter Tickleshoes
- Start date
Unfortunately not, haven't gotten ahold of one to see what it would take to make some of them.
- 12/3/18
- 34,617
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Update - after working on a few more of these, I've discovered another Achilles heel in the design that can manifest whether the jumping hour click spring (JHCS) has broken or not.
The intermediate date wheel (IDW) does not have a support arm anchoring it in position, like the 2836 one does. This can cause it to lift up slightly due to pressure on it from the date wheel driving wheel, often during a date change. When the IDW lifts up, it slips one or more teeth on the uppermost gold colored hour wheel, and the hour hand lags behind or stops until the IDW settles back into position and normal hour wheel rotation resumes.
I believe this potential for lifting of the IDW and gear slipping on the hour wheel increases when the two halves of the GMT wheel are glued together, because then there is more resistance on the IDW and it gives into this resistance by lifting up.
Here's a pic of a lifted IDW and then a normally situated one.
So I found that by making a support arm and sandwiching in under the date plate cover, you can prevent the IDW from lifting up, even after the GMT wheel has been glued. So far it seems to work.
.
The intermediate date wheel (IDW) does not have a support arm anchoring it in position, like the 2836 one does. This can cause it to lift up slightly due to pressure on it from the date wheel driving wheel, often during a date change. When the IDW lifts up, it slips one or more teeth on the uppermost gold colored hour wheel, and the hour hand lags behind or stops until the IDW settles back into position and normal hour wheel rotation resumes.
I believe this potential for lifting of the IDW and gear slipping on the hour wheel increases when the two halves of the GMT wheel are glued together, because then there is more resistance on the IDW and it gives into this resistance by lifting up.
Here's a pic of a lifted IDW and then a normally situated one.
So I found that by making a support arm and sandwiching in under the date plate cover, you can prevent the IDW from lifting up, even after the GMT wheel has been glued. So far it seems to work.
.
- 21/4/19
- 1,806
- 2,157
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Holy smokes, that's a breakthrough! KJ, is there nothing you can't do?Update - after working on a few more of these, I've discovered another Achilles heel in the design that can manifest whether the jumping hour click spring (JHCS) has broken or not.
The intermediate date wheel (IDW) does not have a support arm anchoring it in position, like the 2836 one does. This can cause it to lift up slightly due to pressure on it from the date wheel driving wheel, often during a date change. When the IDW lifts up, it slips one or more teeth on the uppermost gold colored hour wheel, and the hour hand lags behind or stops until the IDW settles back into position and normal hour wheel rotation resumes.
I believe this potential for lifting of the IDW and gear slipping on the hour wheel increases when the two halves of the GMT wheel are glued together, because then there is more resistance on the IDW and it gives into this resistance by lifting up.
Here's a pic of a lifted IDW and then a normally situated one.
So I found that by making a support arm and sandwiching in under the date plate cover, you can prevent the IDW from lifting up, even after the GMT wheel has been glued. So far it seems to work.
.
Sent from my ONEPLUS A6003 using Tapatalk
- 28/2/17
- 2,381
- 1,950
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- 19/1/16
- 4,408
- 5,060
- 113
- 12/3/18
- 34,617
- 66,624
- 113
OK so Auntie Em, it's a TWISTER!
Over a period of days I noticed a slow decay of amplitude after installing the support arm. It turns out the left side of the IDW support arm was imposing some pressure on the datewheel driving wheel which was being transferred to the IDW and then backwards through the whole drive train to the balance assembly. Like a gear dragging on debris or a pinion dragging in a dirty jewel, the movement was being slowed down and s/d was dropping. So I modified the support arm by amputating a finger and I believe I have corrected this issue. So far so good, finger crossed, lol. The benefit of the support arm is still achieved as the IDW doesn't budge upward even with some external lifting force applied.
Over a period of days I noticed a slow decay of amplitude after installing the support arm. It turns out the left side of the IDW support arm was imposing some pressure on the datewheel driving wheel which was being transferred to the IDW and then backwards through the whole drive train to the balance assembly. Like a gear dragging on debris or a pinion dragging in a dirty jewel, the movement was being slowed down and s/d was dropping. So I modified the support arm by amputating a finger and I believe I have corrected this issue. So far so good, finger crossed, lol. The benefit of the support arm is still achieved as the IDW doesn't budge upward even with some external lifting force applied.
Last edited:
- 28/2/17
- 2,381
- 1,950
- 113
OK so Auntie Em, it's a TWISTER!
Over a period of days I noticed a slow decay of amplitude after installing the support arm. It turns out the left side of the IDW support arm was imposing some pressure on the datewheel driving wheel which was being transferred to the IDW and then backwards through the whole drive train to the balance assembly. Like a gear dragging on debris or a pinion dragging in a dirty jewel, the movement was being slowed down and s/d was dropping. So I modified the support arm by amputating a finger and I believe I have corrected this issue. So far so good, finger crossed, lol. The benefit of the support arm is still achieved as the IDW doesn't budge upward even with some external lifting force applied.
Well played sir! Im guessing with the small amount of force needed to keep the wheel down you could go very thin on the finger to reduce drag. Keep us posted mate!
- 12/3/18
- 34,617
- 66,624
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Running perfectly for over a month now.
- 13/6/15
- 2,412
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- 21/4/19
- 1,806
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You could introduce a service to fix/stabilize CHS movements! I know I'd definitely throw money at you if I could have a right proper Noob BLNR
Sent from my ONEPLUS A6003 using Tapatalk
- 9/12/17
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- 390
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To all the expert here, is this the part where the weak spring that fail on us all the time?
The photos are from one of the movement seller, can be purchase as a part.. Seller do not have other photo of it, with my limited knowledge it looks like same, I wonder
- 28/2/17
- 2,381
- 1,950
- 113
To all the expert here, is this the part where the weak spring that fail on us all the time?
The photos are from one of the movement seller, can be purchase as a part.. Seller do not have other photo of it, with my limited knowledge it looks like same, I wonder
The silver 3 piece part is the one that fails. How much does he was for it?
Last edited:
- 9/12/17
- 1,092
- 390
- 83
¥250 + 10 for PRC domestic shipping.
that's about USD 36+- ? Excluding international shipping. Not cheap for a small part, but if one is stuck with it and decline to go for movement swap this will be handy.
- 28/2/17
- 2,381
- 1,950
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I mean its bit cheap but it could be a lot worse. Considering its the impossible part to get to fix your $600 noob watch i think its definitely not too bad.
Phener9
Active Member
Fascinating, some good work gone on here, I hope this part is the way to go otherwise these watches are maybe to be avoided.
For me I seldom set the date and gmt function so would the Noob be a viable watch to own if I didn’t use these?
For me I seldom set the date and gmt function so would the Noob be a viable watch to own if I didn’t use these?
- 28/2/17
- 2,381
- 1,950
- 113
Its luck of the draw really. If you want reliable with easily obtainable parts/new movements i would suggest a vrf gmt. They dont have the pepsi yet but your covered on the other two versions.
- 12/3/18
- 34,617
- 66,624
- 113
There are two points of potential failure in these movements.
1. The jump click spring can break. The spring is located inside the two part GMT wheel, which is held together by the collet. The two halves of the GMT wheel rotate independently if the click spring is intact. If it breaks, the two halves can be epoxied together. It makes no difference if the broken click spring is left inside the GMT wheel for the gluing, although it can act as a containment border for the glue. Once the halves are glued, the GMT and hour hands will be forever synched, but will retain their proper rotation periods (hour hand 2 cycles per 24 hours, GMT hand 1 cycle per 24 hours).
2. The Intermediate Date Wheel (IDW) has no support arm on it in this movement like it does in a native 2836 and 2824. It can get cocked up out of position separately from the click spring breaking. This is due to additional forces placed on it by the datewheel driving wheel around the times of date change (10PM - 2AM). The result is the hour hand becomes stuck or lags behind or is not responsive to crown movements for as long as the IDW is out of position because the hour wheel has become disengaged. Sometimes the IDW will settle back down into position, sometimes not. The potential for this flaw to occur increases when the GMT wheel is glued together because the click spring is not available to absorb any of the pressure exerted on the solid GMT wheel. The fix to this flaw is a custom made IDW support arm fitted underneath the datewheel cover plate.
So, even if you have a spare GMT wheel with an intact click spring, it will not prevent the IDW flaw from occurring. I have fixed that flaw in several of these movements where the click spring never broke. The IDW flaw may never occur, but it is not uncommon.
