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Bulova precisionist quartz to automatic conversion


Marktrev
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Hi All,

My second post and I'm trying to put things on here that might prove useful to others. Please bear in mind, I am an amateur who likes experimenting and I know my techniques won't be looked on favourably by those who pride fine matchmaking! 

Worth me explaining that I have quite a few bulova precisionist watches and I have repaired quite a few. Given the cost of a replacement quartz precisionist movement from Bulova costs £100+ and they dont sell individual parts, it usually makes sense to just source a used watch on ebay, in not great cosmetic condition.

As a result, I have fixed about four watches using two "scrappers", which leaves me with two knackered watches (the coil on both + a number of other broken parts). 

I hate seeing a broken watch so I thought I would try and source a cheap quartz to put in . The only problem is that I couldn't find any wife enough so that the date window fitted. 

Therefore, I thought about a mechanical movement, which would have the bonus of a near sweeping seconds hand. Could not find a mechanical with the right dimensions.

Only movement that I found looked to be a good width was an NH36 (day/date). The day would be hidden by the dial. You will also need hands that fit the nh36 (the bulova ones won't fit)

Before I say all of what you need to do, it is worth noting that I had 2 scrappers under reference: 98b140 and 96G131. 

It is easy to rule one of these models out as the nh36 movement is too deep for the 98b140 (and similar variants). 

 

The same is actually true for the 96g13q and similar variants, but I'll explain how to get round this. 

 

First of all, remove your old movement, and grind off your dial feet - annoyingly they are close to fitting the NH36, but just off a little.

Next you need to bore out the hole in the centre of your dial, by literally the fines amount .2mm maybe.

You need to remove the rotor from your NH36 - that's right, this is going to be manual wound only - not an issue for me as I will use in rotation in my collection, but a pain if you want this to be a daily with the same convenience of the outgoing quartz. 

Next you need to get out your dremel out.

Even without the rotor on, the movement is too deep, so unless you have a cnc lathe to skim some metal off, you need to grind the centre of the inside of the case back to accommodate the protruding part of the movement. You are going to have to eye ball how much to grind out. I used a spherical polishing stone attachment. You may also need to take the surrounding metal down to the same level about 1cm out from the centre point all around. 

The hardest bit for me to do (psychologically speaking) was to grind the thread off the winding stem tube - yep, no more water activities!

Next position your dial and lay out some double sided tape around the outside plastic rim of your nh36. And stick to your dial - say hello to your new "dial feet"! 

Install your hands, and cut stem to fit. And tweak - which I had to a lot. The tweaking was mainly going back and grinding more metal off the case back as if it was tightened on too much it put stress on the movement and stopped it working (yes I know I've probably done the movement some damage!). 

I have it working and despite all the hacking and bodging I'm actually quite happy with it after all, I was guessing on all of this, and could not find anyone else attempting this (why would they! Surely not worth the effort and cost).

My main aim of this post is to help someone considering this, realise that it's really not viable, but if you do want to do it, it is possible for an amateur to achieve. 

 

With regards to the 98b140, I've decided that seen as the nh36 is too deep for the case, I will just use the case and have ordered a new sterile dial from china and a hand wound chinese movement, which should fit. 

Happy to answer any questions, if you are seriously considering this!

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Did you try sniffing around the Chinese market to get an auto that fits?

I have also seen these tiny (Seiko I think) quartz movements that literally glue on the back of the dial, however, this would also mean finding an appropriate plastic spacer.

 

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On 17/08/2020 at 13:48, Biker said:

Did you try sniffing around the Chinese market to get an auto that fits?

I have also seen these tiny (Seiko I think) quartz movements that literally glue on the back of the dial, however, this would also mean finding an appropriate plastic spacer.

 

I did try the chinese autos, but these were all deeper. 

As the bulova has a date window, I was limited to what movements I could put in as I needed the date on the movement to line up with the date window.

With the 98b140, I got my seagull movement, but the height of the hands is too much (up against the glass), so I'm thinking of just putting in a micro quartz, like you suggest and then just sticking the date on the back of the dial - obviously the date wont be functional, but at least it will be right once a month (assuming I chose a number between 1-28!). The problem is finding a quartz movement with high hands to accommodated the thick dial

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