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i thought you guys would like this [emoji1303]

I like to pick out a watch from my collection from time to time and give it a check and run to make sure it's working OK. I was wearing a particularly tight (round the wrist) shirt and sweater the other day, which make checking my watch difficult, so remembered I had a nice 1950s Marvin Hermetic on a Bonklip strap. The Bonklip was designed to be worn outside a shirt or jacket in cold conditions where it had to be referenced easily without constantly pushing up clothing - hence its popularity in aviation. Anyway, I checked out the movement - the regulator is bang in the middle - and have been wearing it for several days now. Perfect time running; a little stiffness when changing the time indicates a clean and lube is probably in order at some stage.

It looks like you will need a wide bifurcated screwdriver to tackle this one. That is a screwdriver with a notch slightly wider than the threaded screw in the centre of the nut. Being a special, it's one you will have to make yourself to ensure a good fit.

The only time I have used one in relation to watchmaking, was checking a couple of components for running true when using my watchmakers lathe. It is unlikely that it would be used for anything else, especially shimming a balance cock. This is something I would do on a trial and error basis, i.e. add shims until you get the the clearance you require by feel. Anyway, you have a jacket tool and would be able to shorten the balance staff to get the correct clearance; this would be the correct way to go.

I would have thought that watchmakers would have a code like "this is a difficult customer' or 'cash only' to warn future watchmakers! But these issues would only turn up when the watch has been cased up.. Anilv

Annoyingly I didn't take a pic of the finished item. But here it is in two halves. I ended up making the stem out of rod scratch,I then hardened it and silver soldered in the section from an ETA split stem. My first attempt was using the orginal stem, but I then realised the smal guide staff on the end was missing, allowing the stem to cock and jam. Hence why I just started from sratch. It worked great in the end. Would be a lot easier if I could have just bought one, though this type of split stem is much better designed than the orignal from EB.

Probably a BFG866 movement. there is a small screw near the stem. Loosening that about two turn and realese the stem and crown. The movement holder is just loose . It's the small tabs that stick out on the side. Just pull straight up.

Here in Sweden i have heard that each watchmaker has number or a approval code from the school. Or an apprentice letter with a number? That number is specific to each watchmaker. And if you have the book or the data you can see which watchmaker did your watch. At least that is for old watches? Don't now how they do this days?

All Marvin movements, as far as I know, were in-house, as you say. The one in my original post is a 520 movement. I also have a 510 which is good, bit not quite as smart as the 520, as you can see below.

It is indeed a dial test indicator. This is usually clamped to the vertical rod on a magnetic base, or in the tool post on a lathe for setting up work to be machined. It can also me used to test for roundness or linear inaccuracies depending how you configure it in relation to the work being examined. Another common use is for setting a vice on a milling to ensure it is perfectly in line with the milling table. There will be many more uses for this precision tool, mostly limited by your requirements and imagination. The one you have in the picture will measure + / - 15 thousands of an inch.

Recorded polishing pivots on a vintage Elgin Pocket Watch. Check it out. Sent from my iPhone using Tapatalk Pro

Well, I decided to remove the piece just to see how consistent the readings would be. This was my very first time using the device and as time goes, I'll probably develop a technique through trial and error. Moving it to a different position and back seems like a good suggestion. After re-checking both watches, both are reading amplitudes between 285 and 305. It seems to have settled down just a bit. As for accuracy and precision... Wow, I'm really impressed. The 7S26C was the one adjusted to 0.0 ms beat error. I wore it all day and it held perfect time. As best as I can tell, it's either dead-on or within 1/2 second of NTP. It sill reads no beat error in most of the 6 positions and it still shows +4s/day in the face down position. That's exactly where it was set to yesterday. The other watch (7S36) was not worn today and gained 7 seconds sitting face-up since it was set about 30 hours ago. I did wind it a little here and there. Its beat error showed 0.3ms and read +5s/day in the face-down position. Those readings have drifted a little from where they were last set. I'll wear this one soon and see how it performs. -Fun stuff for sure... Ray