Accuracy measurement, 1953 Explorer 6150

[Dr_Jon]

I've worked out why my 6150 was keeping so good time recently, after a visit to the servicing people today (just to play with their accuracy measuring machine). It gains around 13s/day Face up, Face down and Crown down but loses about 13s/day with Crown up, which has been the way I've tended to leave it when I'm not wearing it, hence the accuracy has been averaging out...

BTW does anyone know how good the assorted numbers here are (Amplitude, Beat Error and Lift Angle) or what they mean?

Here are images for the four orientations plus a view of the measuring machine complete with my watch.

[sennheiserz]

I recently wrote a blog post about what those numbers mean, you can check it out here, and you can buy your own timegrapher for less than $200 on eBay

http://www.wristtimes.com/blog-1/201...-a-timegrapher

[Dr_Jon]

Originally Posted by sennheiserz

I recently wrote a blog post about what those numbers mean, you can check it out here, and you can buy your own timegrapher for less than $200 on eBay

http://www.wristtimes.com/blog-1/201...-a-timegrapher

Thank you do much for that - just what I was after!

BTW do you have a feel for how my numbers look for a 1953 Explorer? From your blog the crown up/Crown down angles of 225/228 are a bit low and the rest seems okay but I didn't get a feel for the age factor in the results? I'm also not so sure about the use/meaning of the graphs?

Also it shows the Lift Angle as 52.2 degrees - did it work that out or was it set manually by someone? I ask as this document:
http://www.bhi.co.uk/sites/default/f...esandBeats.pdf
Says the A296 is 43 degrees?

P.S. your Witschi link is dead, I think it should now be:
http://www.witschi.com/assets/files/...%20watches.pdf

[jdmi32]

Would love to see more pics of the watch.

[Dr_Jon]

I can do that... Note colour differences in the two internal shots are just down to the lighting. BTW I removed the full serial number, I'm not sure if it matters or not.

[jdmi32]

Wow. I don't know much about the early Explorers but yours is easily one of the nicest ones I've ever seen. Dial, hands and case are in amazing shape. Have you tried in with an Oyster bracelet or on a leather strap?

[Dr_Jon]

I really like the current (non-Rolex) bracelet, the original Oyster bracelet which was "springy/stretchy" used to rip the hairs off my wrist, which was no fun...

Oh, and thanks for the kind words, although I'm not sure it's that great, there is a mark on the face just away from the centre towards 8:30 (the other marks in the photo, other than the one on the perspex between 4-5, are just light reflections). There is also some Radium scattered around.

[Dr_Jon]

I had a request for some more pictures elsewhere, so I'm putting them up here too for those that asked for some. Oh and sorry about the dust on the glass (err, Perspex), it just kept coming back.

[franklin]

Thank you for sharing your photos. I own a modern 36mm explorer and enjoyed comparing the two models.

[jdmi32]

Thanks for the additional pics. It's a great motivator for me to finally add an Explorer to my collection.

[Dr_Jon]

I've been having a discussion with an exceptionally helpful Rolex expert about my watch and he said some very interesting things...

Apparently the 18 jewels on the movement and 7 on the rotor is the top configuration for an A296 and so perhaps it was intended for COSC but failed in some (hopefully very minor) way and they decided to just ship it rather than try to fix it.

It's been quite an education. I now know:

It was a GREAT movement for a non chronometer rated. The intent was that it was to be chronometer rated I'm sure.

The bottom grade auto-wind mechanism had gone from no jewels, simply holes in the plates for the pivots in brass, to 2 hardened steel bushings.

The better grade had 2 ruby jewels in place of those bushings.

The top grade had 7 jewels in the rotor mechanism.

The Chronometer certification process had NOTHING to do with the automatic mechanism at that time and maybe it still does not. It only tests the base movement manually wound. The autowinds are added later to the finished watch.

P.S. as of the last service it now has 19 jewels (26 total), as they replaced one Centre Wheel Jewel and added another:

The center wheel on an 18 jewel watch is jeweled on the train bridge but NOT the mainplate. They added a jewel on the maniplate I feel sure.

[Vincent65]

beauty, congrats!