Adrian-VTA
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Adelaide, South Australia
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Post by Adrian-VTA on Nov 24, 2014 21:08:50 GMT -8
I was just having a look at the specs on the SII NE20 movement and noticed it is a high beat movement. It's still a 7S derived movement, so, would it be possible to transplant the pallet fork and escapement wheel, therefore converting the lower end movements into high beat?
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Adrian-VTA
Global Moderator
Adelaide, South Australia
Posts: 5,327
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Post by Adrian-VTA on Nov 24, 2014 21:16:15 GMT -8
I've studied it a bit more and it looks totally viable!
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Deleted
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Post by Deleted on Nov 25, 2014 10:01:23 GMT -8
I've studied it a bit more and it looks totally viable! Compared the part numbers for the balance, palette, escape wheel and the third wheel. I'm guessing that if the third wheel has the same part number in both calibres, you have a project  |
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Adrian-VTA
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Adelaide, South Australia
Posts: 5,327
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Post by Adrian-VTA on Nov 25, 2014 19:28:37 GMT -8
I've done a bit more of an analysis on this and it still looks feasible. The difference between the 7S/4R etc calibres and the NE20 is the NE20 is a slimline calibre and does away with some of the bridges, replacing them with a main top plate.
So from what I can see, most of the differences in part numbers only affect the length of the fourth wheel etc. Beyond that from what I can see, the parts look interchangeable. There is a different part number on the pallet fork bridge and the third wheel may be a shade shorter to deal with the reduction in height of the movement.
I'm going to need to analyse it a bit more and maybe drop a few bucks on the parts to test it. But I'm still thinking it looks promising. I'm sure most of you guys would love to turbocharge your SKX series divers to high beat if we could do it!
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Adrian-VTA
Global Moderator
Adelaide, South Australia
Posts: 5,327
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Post by Adrian-VTA on Nov 25, 2014 20:11:43 GMT -8
More observations - the train bridge is identical on both and the escapement wheel/pinion pivots on that. So next step is to get that and a pallet fork and give it a try.
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Post by aladinsane on Nov 26, 2014 11:30:17 GMT -8
I may be dense here, but wont you have to change all the wheels of the drive train. Putting the high beat balance in will make the second hand move more times per second, but it will still move the same distance, having the effect of making the watch run very fast.
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Deleted
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Post by Deleted on Nov 26, 2014 12:31:45 GMT -8
I may be dense here, but wont you have to change all the wheels of the drive train. Putting the high beat balance in will make the second hand move more times per second, but it will still move the same distance, having the effect of making the watch run very fast. It's all about gear ratios. As long as the escape teeth spacing is adjusted(ie more teeth added) to the faster moving palette then everything else can remain as is. |
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Adrian-VTA
Global Moderator
Adelaide, South Australia
Posts: 5,327
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Post by Adrian-VTA on Nov 26, 2014 13:58:18 GMT -8
Yeah that's it, the escape wheel moves at the same speed, it's just that it ticks around more often, if that makes sense.
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Deleted
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Post by Deleted on Nov 26, 2014 14:21:48 GMT -8
Yeah that's it, the escape wheel moves at the same speed, it's just that it ticks around more often, if that makes sense. Sort of...it does spin at the same speed but the palette has to engaged and release the extra teeth a a quicker rate. With the 21,600 bph system, the palette will 'tick over' 6 times per second while in the 28,800bph system, the palette will 'tick over' 8 times per second but the escape wheel will spin at the same speed for both. It really needs an animation to make it clear  |
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Post by aladinsane on Nov 28, 2014 14:38:18 GMT -8
I think what i was trying to say above, and Pete commented on is correct. You will need a different gear ratio to make this swap work. If you just plug in the high beat balance, the watch will run crazy fast.
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Post by mwbuss8 on Nov 29, 2014 21:06:13 GMT -8
I think what i was trying to say above, and Pete commented on is correct. You will need a different gear ratio to make this swap work. If you just plug in the high beat balance, the watch will run crazy fast. This is what I thought initially as well, 20min per hour fast. The more I thought about it though, I think Pete is right. The ratio changes at the escapement. Basically the hand moves 1 tick for every 2 beats (back and forth of the balance). With a 21,600 balance and escapement, the 4th wheel is rotated 2 degrees each tick. The 28,800 balance and escapement rotate it 1.5 degrees. If the balance was swapped but not the escapement that's what would make it run fast. On a side note, is there a source for the parts? I can get a complete ne20, but it's about $220. |
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