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Hi everyone

This is my first real post on this forum and my first ever watch project.

I have this Boccia watch dating from about 2000, the movement was starting to fail and the crystal cracked so it has been unused for several years.  It had a nice lightweight and slim titanium case, sapphire crystal and a Myota 6m12 movement - now discontinued.

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My plan is to replace the crystal, fit a new quartz movement (probably a Ronda 703) , replace the face (which I dont like at all) and re-lume or replace the hands.

One thing I am not sure about is which hand fitting height to order.  To align the stem with the casing hole the watch dial needs to be nominally 0.9mm thick 

Looking at the Ronda drawing    https://www.ronda.ch/fileadmin/user_upload/Products/TA_BA/detail/3316001.pdf    confuses me a little and I would appreciate if anyone could confirm if I have got the following right:

1  The dial seat -  Common sense says this is where the movement touches the back of the dial, is this correct?

Assuming it is correct

2  With a 0.9mm dial and hand fitting height No 3  I would have 0.38mm between the hour hand and the face and the second hand would be 1.09mm above the face?

3  With a 0.9mm dial and hand fitting height No 4  I would have 0.73mm between the hour hand and the face and the second hand would be 1.44mm above the face?

4  I will have a minimum of 1.65mm between the face and the crystal (the seal will add a bit) so I assume either of the above will fit OK? 

5  Would No 4 be the best hand fitting height to go for bearing in mind the 0.9mm dial thickness may not be exact?

Any advice much appreciated.

The case has polished up real nice - but that is the easy bit :biggrin:

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Thanks

Mike

 

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cool. good luck with it. I am not overly familiar with the ronda 703. I have played around a bit with the 515. If it will fit, it is my understanding that it's dial feet position are the same as the ETA 28XX calibers. this would give you a lot of dial options.

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1 hour ago, mysterymike said:

I am not planning on using any dial feet but will machine a movement holder/spacer out of delrin which should hold the movement securely and concentric to the dial.

Not a good idea in my opinion, you may think that dial feet are old thinking, but they are perfect for what they hey do. Friction is not a good thing in a watch, parts should just fit precisely. 

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The idea was to make a movement holder and dial that are both a light press fit inside the case, if necessary they can be glued together.  The back of the holder will be machined  so the movement fits in snugly.  There will be a small gap between the movement and the back of the case that will need a plastic or foam shim to keep everything tight.  I would be relying on the stem and the shim to stop the movement rotating.   For belt and braces I could also add dial dots but only if absolutely necessary.

I cannot see why this wouldn't work - but you could fill a library with what I don't know about watch making :)

Making the dial will be the hardest part of the project so I want to avoid the complication of adding dial feet if I can.

I have not found any suitable ready made dials that I like and even if I do, I suspect the feet are unlikely to be in the right place.

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Probably stating the obvious, but a couple of errors I've made with my own current project.

I'm using a convex dial and a Miyota 2033 which obviously will not sit flat against the underside of the dial, so I used dial dots. As luck would have it, the dial dots bring the module into line with the stem. The problem I have is I need to shim the unknown gap between the dial and the hour wheel to stop it disengaging when it is turned over.

I might try a bit of rodico in the gap and try and measure it. I don't like the idea of placing a spacer under the case back in case something gets squashed and distorted. I would have thought a close fitting mov't ring and the stem would hold things in place.

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Hi eezy, not sure what you mean by the gap between dial and hour wheel?

The rodico idea - measuring to see what the gap is is a  great idea.

I was going to machine down the movement holder until tightening the back up keeps the dial in place and then make a spacer to go behind the movement and finish flush with the holder.  

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5 hours ago, mysterymike said:

Hi eezy, not sure what you mean by the gap between dial and hour wheel?

The rodico idea - measuring to see what the gap is is a  great idea.

I was going to machine down the movement holder until tightening the back up keeps the dial in place and then make a spacer to go behind the movement and finish flush with the holder.  

On top of the module in the centre is the wheel and pinion which the hour hand attaches to. Usually nothing holds that in place but a dial washer. In my case using a convex dial, I have a gap there which allows the wheel to come out of mesh when it is tipped up. My gap is bigger than the washer so I need to make a deeper one to make it up.

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You could also keep an eye open on Ebay as the original 6m12-3 movements still pop up New now and again, I picked one up as a spare last week. Which would save the problem with the mounting ring unless you want to mod it anyway.

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I am not planning on using any dial feet but will machine a movement holder/spacer out of delrin which should hold the movement securely and concentric to the dial.

For project watches with missing spacers, I sometimes 3D print spacers if the nett shape is too complex or time consuming to machine. I can cad model and print in a fraction of the time it takes to machine from solid. The results are as good as the original part, although not authentic of course - but ..... the watch is returned to a running and wearable status.


Sent from my iPhone using Tapatalk

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I received my Ronda 703 movement today, it had a couple of extra parts with it that I have no clue what they are for.

The first is a brass coloured washer  - roughly 2mm outside diameter, 1mm inside diameter and curved.

The second is brass coloured plate about 5mm x 1.5mm with an open ended hole at each end.

Does anyone have an idea what these are for?  

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