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Will a gen APROO dial fit an A7750 sec@6 movement?

sander

By sander
in The Audemars Piguet Area

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sander Newbie

sander

Posted
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The problem with the gen dial is that the date window is in the wrong position. It has the window about 1mm too much to the left.

To make it work, you need a smaller date disk and the date window in the movement has to be moved to the left. Is this impossible???

Recently I did a project with a Lemania 283 movement. see here: http://www.rwgforum....-my-holy-grail/

This movement is build with a Dubois Depraz chrono module on top of a ETA 2892 movement. This means that the date disk for an ETA 2892 will fit a gen dial.

Now the first question is, how to fit the smaller 2892 date disk into a 7750 movement????

First I removed the teeth and sanded the disk down from 0,35mm to 0,13mm.

Than I took the 7750 disk and sanded it down from 0,48 to 0,35. After that I glued them together and the total high was 0,52mm (so I guess the glue is 0,04mm thick)

So overall it's 0,04mm higher than the standard 7750 disk. This is not a problem.

When you install the new disk, you will notice that it will rub the date jumper plate and the date indicator plate.

I sanded them down, but unfortunately I sanded the date jumper plate a little too far. Because of this, the date jumper didn't work properly anymore.

After I made a new plate, the date changed without any problems.

post-9210-12707206444_thumb.jpg

After installing the extra gears to move the seconds to the 12 position, I noticed that the gap between these gears and the date disk, was big enough to have the disk freely move .

So now the date is in the right position for the gen dial.

post-9210-127072065333_thumb.jpg post-9210-127072065934_thumb.jpg

After this I had to move the date window about 1mm to the left. The date window is attached to the plate which sits on top of the movement.

I cut it off and enlarged the hole in the plate. After removing the window, I mounted the plate and noticed that everything worked as it should do.

I also enlarged the date hole in the next plate (the one that holds the extra gears in place). So I ended up with a complete movement with a big hole instead of a date window.

post-9210-127072066757_thumb.jpg post-9210-127072067765_thumb.jpg post-9210-127072068635_thumb.jpg

Now I needed to install the cut off date window into the big hole. For this I used the thin plate which is located right underneath de dial.

I made the existing hole bigger and used some epoxy to glue the date window in the right position. After the glue dried, I sanded the plate and painted it black.

When I positioned the plate with the window on the movement, it was perfect!

post-9210-127072069452_thumb.jpg post-9210-127072070096_thumb.jpg

Since I'm not having an extra gen APROO dial at the moment, I made one myself to see if it works.

(I knew I was going to do this mod, so before I installed my gen dial in the above mentioned project, I copied it for the exact measurements)

After the dial was finished and installed, I was thrilled to see that it worked.

post-9210-127072070853_thumb.jpg post-9210-12707207168_thumb.jpg post-9210-127072072411_thumb.jpg post-9210-127072073155_thumb.jpg post-9210-127072073848_thumb.jpg post-9210-127072074643_thumb.jpg

So yes it's possible to put a gen dial on a 7750 movement but it needs a lot of modding.

Cheers,

Sander

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txcollector Newbie

txcollector

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this is awesome Sander.

I see this method as easier to do since the only additional part (apart from the dial) would be the DW. In the DD approach you need a new movement and some serious case mods. However this DW mod won't fix the crown position.

Between the 2 methods (Dubois Depraz chrono module vs using the ETA 2892 on a modified 7750 based sec@12 donor, which one do you prefer?

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sander Newbie

sander

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this is awesome Sander.

I see this method as easier to do since the only additional part (apart from the dial) would be the DW. In the DD approach you need a new movement and some serious case mods. However this DW mod won't fix the crown position.

Between the 2 methods (Dubois Depraz chrono module vs using the ETA 2892 on a modified 7750 based sec@12 donor, which one do you prefer?

Well let me start to say that they are both not easy.

The biggest problem with the DD module, was to find out how to use the chrono pushers because they don't line up. This took me hours and hours and hours and hours. Also If you don't have gen hands you have a challenge. The DD module needs a 0,90mm minute hand and 1,20mm hour hand. The rep comes with 1,20 minute hand and a 2,00 mm hour hands. Of course also all the chrono hands needs to be broached from 0,20mm to 0,25mm.

I will try to write a post about it tomorrow.

The mod with the 7750 movement was pretty much straight forward. It worked exactly as I planned. The only problem is that you have to work with really small margins. So it's really easy to screw it up.

I found it also very frustrating to sand down the date disk to 0,13 mm. No power tools here, just some sandpaper.

I think yhe most complicated part of mods like these, is to figure out what the best method is.

Also you need a lot of spare parts and you shouldn't be affright to take some expensive risks happy.gif

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sander Newbie

sander

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@sander

just curious:

maybe stupid question but anyway, is the gap to the left with a gen AP ROO dial

really as much as one entire mm or less?

It's less. I'm not really sure what the best way to measure it because all the dimensions are different.

I made you a drawing so that you can take a look.

The 7750 date disk is 1,3mm bigger than the 2892 disk (24,55mm -/- 23,25mm)

If you defied that by 2 the difference is 0,65mm. Maybe this is the easiest way to tell?

post-9210-127075971028_thumb.jpg

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HauteHippie Newbie

HauteHippie

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Going to have to take a closer look and read this through once more. I'd more or less written off this model even though this it is one of my favorite gens of all. I had just not been interested in the 7750 version and didn't think what you've done was possible. Thanks for pioneering the way, but I have to admit you're making it sound a lot easier than it is.... making a new plate, sanding down datewheels and gluing them together keeping the alignment perfect... no easy tasks.

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Jkay Newbie

Jkay

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To answer the question you posed in your other thread ... your problem was the topic you chose. It asks a rather obscure question instead of proclaiming loudly that you've cracked an un-solvable problem.

Your topic deceived members into ignoring your post.

Congratulations to you, and thank you for putting a lot of work into solving a problem that no one knew could be solved.

:1a:

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krpster Newbie

krpster

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Holy moley! :shock: That is amazing work right there! Im not an AP guy but I sure can appreciate ingenuity at it's finest. Well done! :tu: I am sure many will be able to take advantage of this kind of information although few will attempt I'd wager since it seems a significant amount of skill is required. Kudos! Now post some pics of the final product! I wanna see I wanna see! :bounce:

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sander Newbie

sander

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Holy moley! shock.gif That is amazing work right there! Im not an AP guy but I sure can appreciate ingenuity at it's finest. Well done! thumbsup.gif I am sure many will be able to take advantage of this kind of information although few will attempt I'd wager since it seems a significant amount of skill is required. Kudos! Now post some pics of the final product! I wanna see I wanna see! bounce.gif

Here you go mate!: http://www.rwgforum.com/topic/115655-ultimate-modded-watch-finished/page__pid__822657__st__0&#entry822657

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