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The Water Cooler
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Another OSA Owned Watch Rebuild – 1961 Bulova Type A17A Military Issue Navigation Watch
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<blockquote data-quote="thor447" data-source="post: 3915192" data-attributes="member: 24867"><p>I took a few photos showing the mainspring and arbor assembled into the barrel, as well as the wheel train assembly before the bridge was re-installed.</p><p></p><p>[ATTACH=full]326518[/ATTACH]</p><p>[ATTACH=full]326519[/ATTACH]</p><p></p><p>On one of these builds in the future I'd like to get some video of the lubrication process. It's done under really high magnification, and while it looks great through my microscope, when I'm zoomed in that far the video comes out rather dark. It is interesting to see though. When the watch is running, and you oil a jewel, you can see the oil get drawn down into the pivot through capillary action. I'll either have to eventually upgrade my microscope camera or figure out those darn settings to make the video appear as good as it looks through my microscope. It may be a lighting issue, I have no clue, but I think you all would enjoy seeing that part of it. One of these days I'll figure out a solution to capture high quality video at that magnification that doesn't cost an arm and a leg.</p><p></p><p>Assembly went well for the most part. After assembling everything aside from the balance, side shake and end shake were checked on all parts, from the barrel, to the wheel train, and pallet fork. Aside from the adjustment on the barrel bridge for the side shake on the mainspring barrel arbor that was detailed earlier, no other adjustments were needed.</p><p></p><p>There was one thing however that made my heart stop for a moment though on this watch. Everything had been going really well during reassembly. I got to the very end, and on this watch, that was re-installing the balance assembly. For the life of me I couldn't get the balance to sit level no matter what I did. At this point I had been working on the watch for about 2.5 hours straight. What I didn't realize is that I had the crown pulled all the way out, which meant the hacking lever was in the position to interrupt the balance wheel. With this lever in the way, the balance would not find it's natural resting place. It took me a few minutes and then the 'duh' moment came. I pushed the crown back in, re-seated the balance again and it found it's lower jewel. This is when the bigger problem showed it's ugly head! The balance would find center and seat, but when the balance wheel would start to kick in, it would barely rotate at all. It was nowhere close to what it should be doing. I inspected it from every possible angle and found that the balance wheel itself was sitting too high, so much so that it was actually just barely touching the underside of the center wheel of the watch.</p><p></p><p>[ATTACH=full]326521[/ATTACH]</p><p></p><p>I looked and looked and could not find any problems. I must have removed the balance 5 or 6 times trying to get it going. I was doing it so much that I began to worry about breaking a balance pivot (which is very easy to do). When inspecting the balance pivots, you can visually see the lower balance pivot pretty easily, and under the highest magnification I can produce, I inspected it at every angle to make sure it wasn't broken or bent. I pulled out the balance assembly, put it in a suspension mount so that the wheel hangs with gravity an opens up the hairspring coils. From this view I could visually see that the upper balance staff pivot was also not broken or bent. I was then thinking that I must have damaged the hairspring somehow. After inspecting the hairspring everything look exactly like it should, but the wheel was just sitting to high no matter what I tried. I began to really worry because this wasn't my watch, and finding a replacement balance (this one is an older style as previously mentioned, and not nearly as available as other types would be) would be nearly impossible, and unbelievably expensive. The only way to really get one would've been to buy another vintage authentic MIL-W-6433A watch. I decided to step away from the bench for a few minutes and calm my nerves. I was a Pucker Factor 10!!</p><p></p><p>After about 20 minutes of being away from the desk the solution hit me like a ton of bricks! Normally when I assemble a watch, I clean and re-lubricate the balance shock springs, chatons (inner balance jewel assembly with setting for the spring to mount), and cap jewels individually, after the main cleaning has been done and the watch balance has been re-installed. On this watch everything was going really well during disassembly, so I decided to try to and disassemble these parts and clean them during the main process (as I've seen others do). When I reassembled the balance lower jewel setting, I did it before any work began on assembling the watch. On these jewel settings, the cap jewel (the outer one that you can actually see) has a flat side and a domed side. Usually these sides are very easy to distinguish under magnification and how the light reflects off of each side. The flat side is what gets the lubrication, and faces inwards towards the balance staff pivot. On this watch, the domed side only has the very slightest of curves, so much that I made the mistake of assembling it backwards. Normally you wouldn't be able to get the cap jewel to seat in the chaton, much less get the shock spring fully in place with it in upside down. With these, the dome was so slight that it actually went fully back together. My mistake is that I had the domed part of the jewel facing inward. This meant that there was less room inside that jewel setting for the lower balance staff pivot to go into, and thus it raised the height that the balance staff (and everything connected to it). We are talking a TINY amount here, but it was enough to throw everything out of whack. Once I found my error and wore my imaginary dunce cap for a few minutes, I re-cleaned, lubricated, and correctly assembled the lower balance staff jewel setting. Once that was done the balance staff would sit down lower in the jewel setting, right where it needed to be, and the watch kicked up and started to run like a race horse just let out of the gate!</p><p></p><p>After the movement was assembled I put it on the timegrapher and did a quick regulation (only to a single position), and let it run in for 24 hours.</p><p></p><p>[ATTACH=full]326517[/ATTACH]</p><p></p><p>While these numbers are outstanding, they will not be the end result. This was adjusted immediately after the watch was assembled, and only adjusted to a single position, in this case – dial down. You can clearly see that it is keeping good time, and the amplitude is an astounding 312 degrees. This is really great, but you don't want to go much more above 325 or your begin to get into the territory of knocking. A watch knocking is where the impulse jewel on the underside of the balance (the piece that actually engages with the pallet fork) travels so far that it hits the opposite side of the pallet fork. The point of rotation where this begins to happen can vary, but starting at about 325 degrees and higher you start to get into dangerous territory. At 312 degrees, I am very happy with this, but the watch and lubrication will settle in from this point and the amplitude will come down slightly.</p><p></p><p>After the 24 hour run in and full assembly, I regulated the watch to 3 positions – Dial Up, Dial Down, Crown Down. Here's the reading at Dial Up:</p><p></p><p>[ATTACH=full]326520[/ATTACH]</p><p></p><p>There is only about a 6 second difference between all three positions, which is <u>really</u> great. Beat error is steady around 2.1 m/s, which is just fine for this type of older movement. While it is acceptable on this watch, and it will keep accurate time with that beat error rate, seeing those separated lines on the timegrapher kicks my OCD into overdrive and makes my right eye start to twitch, lol. The timegrapher is the best, and at the same time, the worst tool I have. It makes you strive for perfection in timekeeping, even when the results you seek aren't possible on the watch your working on. I find myself wanting to get atomic level accuracy from a mechanical watch, and I want to see perfectly flat single lines on the timegrapher. What I have to remember sometimes is that it is a mechanical device, and will never be perfect, but it is good enough that at whatever point you look down at your watch, it'll be correct. I see a watch running at +3 seconds per day, and I want to see if I can get it down to zero. It's maddening sometimes, lol.</p><p></p><p></p><p>Continued on next page.</p></blockquote><p></p>
[QUOTE="thor447, post: 3915192, member: 24867"] I took a few photos showing the mainspring and arbor assembled into the barrel, as well as the wheel train assembly before the bridge was re-installed. [ATTACH type="full" alt="33.JPG"]326518[/ATTACH] [ATTACH type="full" alt="34.JPG"]326519[/ATTACH] On one of these builds in the future I'd like to get some video of the lubrication process. It's done under really high magnification, and while it looks great through my microscope, when I'm zoomed in that far the video comes out rather dark. It is interesting to see though. When the watch is running, and you oil a jewel, you can see the oil get drawn down into the pivot through capillary action. I'll either have to eventually upgrade my microscope camera or figure out those darn settings to make the video appear as good as it looks through my microscope. It may be a lighting issue, I have no clue, but I think you all would enjoy seeing that part of it. One of these days I'll figure out a solution to capture high quality video at that magnification that doesn't cost an arm and a leg. Assembly went well for the most part. After assembling everything aside from the balance, side shake and end shake were checked on all parts, from the barrel, to the wheel train, and pallet fork. Aside from the adjustment on the barrel bridge for the side shake on the mainspring barrel arbor that was detailed earlier, no other adjustments were needed. There was one thing however that made my heart stop for a moment though on this watch. Everything had been going really well during reassembly. I got to the very end, and on this watch, that was re-installing the balance assembly. For the life of me I couldn't get the balance to sit level no matter what I did. At this point I had been working on the watch for about 2.5 hours straight. What I didn't realize is that I had the crown pulled all the way out, which meant the hacking lever was in the position to interrupt the balance wheel. With this lever in the way, the balance would not find it's natural resting place. It took me a few minutes and then the 'duh' moment came. I pushed the crown back in, re-seated the balance again and it found it's lower jewel. This is when the bigger problem showed it's ugly head! The balance would find center and seat, but when the balance wheel would start to kick in, it would barely rotate at all. It was nowhere close to what it should be doing. I inspected it from every possible angle and found that the balance wheel itself was sitting too high, so much so that it was actually just barely touching the underside of the center wheel of the watch. [ATTACH type="full" alt="55.JPG"]326521[/ATTACH] I looked and looked and could not find any problems. I must have removed the balance 5 or 6 times trying to get it going. I was doing it so much that I began to worry about breaking a balance pivot (which is very easy to do). When inspecting the balance pivots, you can visually see the lower balance pivot pretty easily, and under the highest magnification I can produce, I inspected it at every angle to make sure it wasn't broken or bent. I pulled out the balance assembly, put it in a suspension mount so that the wheel hangs with gravity an opens up the hairspring coils. From this view I could visually see that the upper balance staff pivot was also not broken or bent. I was then thinking that I must have damaged the hairspring somehow. After inspecting the hairspring everything look exactly like it should, but the wheel was just sitting to high no matter what I tried. I began to really worry because this wasn't my watch, and finding a replacement balance (this one is an older style as previously mentioned, and not nearly as available as other types would be) would be nearly impossible, and unbelievably expensive. The only way to really get one would've been to buy another vintage authentic MIL-W-6433A watch. I decided to step away from the bench for a few minutes and calm my nerves. I was a Pucker Factor 10!! After about 20 minutes of being away from the desk the solution hit me like a ton of bricks! Normally when I assemble a watch, I clean and re-lubricate the balance shock springs, chatons (inner balance jewel assembly with setting for the spring to mount), and cap jewels individually, after the main cleaning has been done and the watch balance has been re-installed. On this watch everything was going really well during disassembly, so I decided to try to and disassemble these parts and clean them during the main process (as I've seen others do). When I reassembled the balance lower jewel setting, I did it before any work began on assembling the watch. On these jewel settings, the cap jewel (the outer one that you can actually see) has a flat side and a domed side. Usually these sides are very easy to distinguish under magnification and how the light reflects off of each side. The flat side is what gets the lubrication, and faces inwards towards the balance staff pivot. On this watch, the domed side only has the very slightest of curves, so much that I made the mistake of assembling it backwards. Normally you wouldn't be able to get the cap jewel to seat in the chaton, much less get the shock spring fully in place with it in upside down. With these, the dome was so slight that it actually went fully back together. My mistake is that I had the domed part of the jewel facing inward. This meant that there was less room inside that jewel setting for the lower balance staff pivot to go into, and thus it raised the height that the balance staff (and everything connected to it). We are talking a TINY amount here, but it was enough to throw everything out of whack. Once I found my error and wore my imaginary dunce cap for a few minutes, I re-cleaned, lubricated, and correctly assembled the lower balance staff jewel setting. Once that was done the balance staff would sit down lower in the jewel setting, right where it needed to be, and the watch kicked up and started to run like a race horse just let out of the gate! After the movement was assembled I put it on the timegrapher and did a quick regulation (only to a single position), and let it run in for 24 hours. [ATTACH type="full" alt="22 - Initial Regulation After Assembly.JPG"]326517[/ATTACH] While these numbers are outstanding, they will not be the end result. This was adjusted immediately after the watch was assembled, and only adjusted to a single position, in this case – dial down. You can clearly see that it is keeping good time, and the amplitude is an astounding 312 degrees. This is really great, but you don't want to go much more above 325 or your begin to get into the territory of knocking. A watch knocking is where the impulse jewel on the underside of the balance (the piece that actually engages with the pallet fork) travels so far that it hits the opposite side of the pallet fork. The point of rotation where this begins to happen can vary, but starting at about 325 degrees and higher you start to get into dangerous territory. At 312 degrees, I am very happy with this, but the watch and lubrication will settle in from this point and the amplitude will come down slightly. After the 24 hour run in and full assembly, I regulated the watch to 3 positions – Dial Up, Dial Down, Crown Down. Here's the reading at Dial Up: [ATTACH type="full" alt="38.JPG"]326520[/ATTACH] There is only about a 6 second difference between all three positions, which is [U]really[/U] great. Beat error is steady around 2.1 m/s, which is just fine for this type of older movement. While it is acceptable on this watch, and it will keep accurate time with that beat error rate, seeing those separated lines on the timegrapher kicks my OCD into overdrive and makes my right eye start to twitch, lol. The timegrapher is the best, and at the same time, the worst tool I have. It makes you strive for perfection in timekeeping, even when the results you seek aren't possible on the watch your working on. I find myself wanting to get atomic level accuracy from a mechanical watch, and I want to see perfectly flat single lines on the timegrapher. What I have to remember sometimes is that it is a mechanical device, and will never be perfect, but it is good enough that at whatever point you look down at your watch, it'll be correct. I see a watch running at +3 seconds per day, and I want to see if I can get it down to zero. It's maddening sometimes, lol. Continued on next page. [/QUOTE]
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Another OSA Owned Watch Rebuild – 1961 Bulova Type A17A Military Issue Navigation Watch
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