Seiko Bell-Matic 4006-6040

I’ve written about Seikos Bell-Matic alarm watches before but I thought I’d feature this one as it’s a complete tour-de-force of problems you can find with a watch! It came in for a service, a spruce up and a relume as the minute hand had lost a small section of lume and the owner wanted it to glow again. I was told it had been running, then it ran intermittently, then it wouldn’t run at all – dirt and debris in the movement or a loose screw rattling around inside perhaps? Time will tell! The watch is a 4006-6040 with a gold dial and contrasting black alarm indicator ring, and arrived on its original bracelet. The first thing I noticed when winding the alarm was that the spring was slipping so that would also need addressing as the alarm wouldn’t sound for as long as it should, needless to say it wasn’t a runner.

Seiko Bell-Matic 4006-6040

The caseback revealed a production date of June 1976, it was a blistering summer here in the UK that year!

Seiko Bell-Matic 4006-6040

With the back removed the movement could be seen and I spotted a serious problem immediately.

Seiko Bell-Matic 4006-6040

The hairspring was mangled! It looks like the beat lever had been shoved around and had bunched the hairspring up against the curb pins, you can see how this has knocked all the coils off centre as they are poking right out the right hand side and are forced against the staff on the left. This isn’t good, the 4006a is a 19,800bph calibre and balance assemblies are very difficult to source.

Seiko Bell-Matic 4006-6040

With the beat lever moved back things didn’t improve much, it appeared the hairspring was still wrecked. In the normal course of events I wouldn’t attempt to rectify this I’d just try and source a new balance, however, as I previously said these are very difficult to find nowadays. This forced my hand as in the absence of a replacement I’d have to see what I could do with it. I tackled this part before I stripped the watch any further as if this wasn’t successful (in the absence of a replacement) it would be a waste of time continuing with the service.

Seiko Bell-Matic 4006-6040

After much wrangling I managed to get the spring looking like this so that it was centred properly and it passed correctly through the curb pins, I also had to reform the collins curve where the spring kinks in to the main coil after the regulating section.

Seiko Bell-Matic 4006-6040

A hairspring has to have it’s coils centred and the curve has to pass through the curb pins with the correct clearance throughout the arc of the regulator, but it also has to be flat as any distortion in the horizontal plane will cause it to rub on either the balance or the balance cock. As you can see after reshaping the spring it most definitely wasn’t flat and level!

Seiko Bell-Matic 4006-6040

This is the hardest part to get right, it’s very difficult to bend it in the horizontal plane without affecting the concentricity of the spring, and don’t forget the complete balance is about half the width of a thumbnail! Again after much tweaking I managed to get it looking as it should.

Seiko Bell-Matic 4006-6040

At this point I refitted the balance assembly and wound the mainspring to see how it would perform, it spluttered into life with a very weak amplitude and didn’t run for very long. This gave me some hope so I removed the balance again and had a closer look to see what was causing the stopping now the balance appeared OK. Looking at the escape wheel and pallet fork I could see they were soaked in oil, which is a big no no, and could explain why it was struggling to run continuously. Again this was a good sign, once it was cleaned and properly lubricated the movement should run properly so I decided to carry on with the service.

Seiko Bell-Matic 4006-6040

The watch was turned over and the stripdown began in earnest. The movement was uncased ready for the dial and handset to be stripped.

Seiko Bell-Matic 4006-6040

Under the dial the calendar wheels looked to be in good shape.

Seiko Bell-Matic 4006-6040

However with the day wheel removed there was more excess oil on this side, not a good sign.

Seiko Bell-Matic 4006-6040

With the calendar work on top plate removed a lot more oil could be seen.

Seiko Bell-Matic 4006-6040

And with all the keyless and alarm work removed the mainplate was soaked.

Seiko Bell-Matic 4006-6040

The movement was turned over to start on the motion work.

Seiko Bell-Matic 4006-6040

The pallet fork was removed, this is meant to be dry apart from a tiny film of oil just on the bearing surfaces of the endstones!

Seiko Bell-Matic 4006-6040

The bridge was removed and once again, more oil!

Seiko Bell-Matic 4006-6040

The rest of the movement was stripped….

Seiko Bell-Matic 4006-6040

….and it was soon ready for cleaning and inspection.

Seiko Bell-Matic 4006-6040

Seiko Bell-Matic 4006-6040

Whilst the components were being cleaned I cracked on with reluming the dial and hands, in these shots the old lume has been stripped.

Seiko Bell-Matic 4006-6040

Seiko Bell-Matic 4006-6040

Also the crystal needed some work, an original isn’t easily sourced so I sanded the worst of the damage from the existing one and repolished it.

Seiko Bell-Matic 4006-6040

I mentioned earlier that the alarm spring was slipping when it was wound, and this is the reason why. The old spring is situated above the replacement and you can see that the resilient hooking that catches on the barrel wall was broken on the old one. This meant that as the spring was tightened onto the arbor during winding it pulled it away from the slot in the barrels wall resulting in it slipping. The resilient hooking tab should be the length of the bottom spring in the picture.

Seiko Bell-Matic 4006-6040

The other issue was the third wheel top jewel had been broken. Here’s a picture of it after cleaning.

Seiko Bell-Matic 4006-6040

This is a better shot with some light behind it.

Seiko Bell-Matic 4006-6040

This usually happens when the bridge has been tightened down without the pinion being seated in the hole, on either on the top jewel or bottom bearing. An inspection of the bearing shows that the pinion hadn’t been aligned at this end, the bridge was tightened down and the force shattered the jewel at the other end of the pinion, also damaging this bearing. I placed the third wheel into this bearing to see if it was rubbing and of course it was, I could turn the plate upside down and it wouldn’t drop out! This meant this bearing needed replacing too.

Seiko Bell-Matic 4006-6040

I dealt with the top jewel first, the remains of the old jewel was pressed out with my Seitz jeweling tool using a pump pusher and suitable sized anvil.

Seiko Bell-Matic 4006-6040

I adjusted the tool so the pusher had enough travel to actually push the jewel cleanly out, then put the plate into position and pressed the lever down.

Seiko Bell-Matic 4006-6040

The shattered jewel crumbled out leaving a nice clean hole.

Seiko Bell-Matic 4006-6040

A suitable jewel was selected from a pile of spares.

Seiko Bell-Matic 4006-6040

The jewel has to fit the third wheels pinion snugly with about five degrees of movement either side of vertical, this ensures its going to run freely and remain lubricated.

Seiko Bell-Matic 4006-6040

It also has to be either the correct size or a little larger than the hole in the plate. Too small and it will just drop out! This jewel was a little larger than the existing hole.

Seiko Bell-Matic 4006-6040

To rectify this a ‘D’ cutter or reamer is used in the Seitz tool to open out the hole to the correct diameter. This is placed in a handle which is dropped into the tool, you then slowly rotate it and it shaves a tiny amount of metal from the side of the jewels hole. The hole ends up slightly tapered (like most modern jewel holes) so always press a jewel in from below because of this. In days gone by jewels were ‘rubbed in’, where the hole was parallel and the ends were swaged over each end of the jewel to hold it in place, there are many drawbacks with rubbed in jewels not least setting the endshake is a right royal pain!

Seiko Bell-Matic 4006-6040

Once the hole was the correct diameter the jewel was pressed home to sit flush with the plate.

Seiko Bell-Matic 4006-6040

Seiko Bell-Matic 4006-6040

I found a serviceable top bearing in the parts drawer again it was checked on the third wheel bottom pinion for fit.

Seiko Bell-Matic 4006-6040

Then I knocked the old bearing out with my Boley staking tool.

Seiko Bell-Matic 4006-6040

The new bearing was pressed in flush with the same tool using a larger diameter stake. This is how it should look in comparison with the wrecked one!

Seiko Bell-Matic 4006-6040

The pinion and bridge were then test fitted to check the endshake. This proved to be acceptable and the wheel ran freely so the rest of the train was test fitted to check for clearance.

Seiko Bell-Matic 4006-6040

The clearance between the centre and third wheel proved to be too tight so the third wheel had to be lowered, but using the jeweling tool this can be done very accurately. With the correct pusher and anvil fitted to the tool the plate is put in place and the pusher is brought down to rest on the jewel. The graduated scale at the adjustment end of the tool is then wound up so that it hit the levers stop and a note is made of the reading which in this case was 6 on the scale. I wanted to lower the jewel by 0.15mm so the knurled screw was turned to 21 (each graduation equates to 0.01mm) and the jeweling tool was then pressed down fully to its stop.

Seiko Bell-Matic 4006-6040

The result is the jewel is lowered in its hole by 0.15mm.

Seiko Bell-Matic 4006-6040

The procedure is repeated on the bearing in the train bridge and the rebuild can start again. Almost! Another casualty of the forced bridge was the escape wheel, amazingly it ran with the bottom pinion snapped off and stuck in the jewel.

Seiko Bell-Matic 4006-6040

A NOS escape wheel was located and purchased.

Seiko Bell-Matic 4006-6040

And the final casualty was the pallet fork. Again I presume when the bridge was tightened down incorrectly the escape wheel must have been on top of the entry pallet end stone which had dislodged it. It had been straightened so the watch ran, but hadn’t been fixed with shellac so the slightest knock would result in this happening, which needless to say would stop the watch dead. I had a replacement in the parts drawer so I used that rather than getting the spirit lamp and shellac out.

Seiko Bell-Matic 4006-6040

Now the rebuild could continue, the train was refitted….

Seiko Bell-Matic 4006-6040

….and was soon in a state where I could do the rough timing adjustments.

Seiko Bell-Matic 4006-6040

The alarm/calendar side was rebuilt next.

Seiko Bell-Matic 4006-6040

Seiko Bell-Matic 4006-6040

The day wheel was re-installed ready for the relumed dial….

P1040650a

….handset and alarm ring.

Seiko Bell-Matic 4006-6040

The movement was recased….

Seiko Bell-Matic 4006-6040

….then I rebuilt the autowind mechanism and fitted it and the rotor.

Seiko Bell-Matic 4006-6040

With the caseback replaced the watch was finally done! It was a bit of a mission this one but considering where it started from I think it’s had a remarkable transformation.

Seiko Bell-Matic 4006-6040

Seiko Bell-Matic 4006-6040

Seiko Bell-Matic 4006-6040

13 comments

    1. It depends what you’re after, balance wheels are problematic as they are also used in the 6215 diver and a couple of Grand Seikos, when they appear for sale they tend to go quickly. Train wheels aren’t as bad but I got lucky with the escape wheel, as with any 40 year old watch parts availability is going to be patchy at best!

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  1. Hi, I have just come into possession of a Bell Matic 4006 6040 that belonged to my late dad. It looks in pretty bad shape with the glass broken, no bracelet and the watch not running. Can you offer any advice on who/where I could take it to see if it can be restored? Thanks

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  2. Hi, I have my fathers Bell matice 4006-6080 which has the same shaped case as the one in this article. Watch works fine however, I need a replacement strap. Any ideas were I can get one or an alternate of some sort.

    Thanks.

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    1. The best place for a replacement strap or bracelet has to be ebay, you can either keep your eyes peeled for an original type or choose one you think would just suit the watch.

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  3. I have bell-matic 4006-6040 in good condition but the steel or chrome Bezel round the glass is missing can you advise me where to get one .

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