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Ronda 515 to ETA F06.111 conversion


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Hi all, newbie here. I guess I've ended up a bit of a watch fan with a bunch of watches in my current collection (pic below), plus a few others I've sold.

I haven't done that much modding of my watches, just battery changes and realigning hands on a few occasions. But I did put together a Series One watch from buildyourownwatch.com a few years (which I've actually sold since). At some point I would like to get more into building my own design, but baby steps first ;)

Anyway, my Helgray Field Officer II watch has been a trusty daily beater for some time, with a quartz Ronda 515 movement. The battery ran out a few weeks ago, so I ordered a replacement, put it in - watch didn't restart? Tried with a different battery, nada. Both were new batteries in original packaging with expiry dates years in the future. After looking around I found a few others online saying they'd had similar experiences when replacing the battery on a Ronda 515 movement. Seems like the movement is prone to dying at battery replacement time.

So after a bit of hunting around at specs and seeing what I could easily get a hold of locally, I decided to give an ETA F06.111 movement a go as a replacement (https://shopb2b.eta.ch/f06-111-f06.1111597973808.html). It's shows up on the ETA website as discontinued and replaced by F06.115, but I couldn't find that locally and there didn't seem to be much difference between them.

There was a 0.5mm difference in stem to dial height from the F06.111 to Ronda 515, but hand sizes etc. were all the same, and the key deciding factor was a much better battery life - 68 months using a Renata 371, as opposed to 45 months for the 515.

Good news - it all worked. Switched over the hands to the new movement - even with tweezers and a hand press, I still find fitting hands the fiddliest of all! The hands maybe did get a little beat up from pinging out of my tweezers so often. The second hand isn't perfectly aligned but maybe I'll have another go some other time on that. Seems to me there's a market for a simple watch hand-friendly clamp, with a fine x-y axis adjustment to line it up to the dial and press mechanism to fit hands accurately and softly. Also needed to switch the crown onto the new stem and cut it to fit. Once the stem is in the new movement, the crown does sit at a slight angle if you look closely from the side, due to the 0.5mm difference in stem to dial height between the movements, but the actual date/time mechanism etc all works fine.

I have a Renata 395 battery on the way, which the ETA movement can take and ups the battery life to 94 months!

A few pics, and the Field Officer back in the working collection :)

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There's enough room in the stem hole in the case to easily slide the stem in and out. Once you put it right in, the crown does sit at a slight angle - shown in the photo below.

One option would be to insert a 0.5mm spacer between the dial and movement to bring the stem down. Maybe I'll look into sourcing one and see how well that works - it would pull the hand height down by 0.5mm and I think the minute hand might hit the applied markers on the dial, because it's fairly close at the moment.

But everything seems to be working fine as is :)

crown.jpg

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