Jump to content

Advice request- removal of bezel and tachymeter ring Seiko 7T94 0BS0


Recommended Posts

Hi

I've just acquired a Seiko 7T94 0BS0 Quartz Chronograph for clean up and restoration. It is scratched and filthy but otherwise fully functional.

It has a black coated bezel into which the crystal is embedded. There is a tachymeter chapter ring under the crystal sandwiched between the crystal and the body of the watch.

I assumed I'd be able to prise off the bezel to release the chapter ring to allow me to clean and polish the case.

The I can't seem to remove the bezel.. but the chapter ring is slightly loose. I'm uncertain if that is how it was when I received the watch. I think it's held in place by the movement.

If that bezel is removable I'd like to get it off so I can thoroughly clean and polish the case... and touch up or re-coat the bezel.

I'm at a bit of a loss. I can't see a way of pushing it out from the inside as the channels for the pushers and stem intrude into the watch body.

Photos below.

Thanks in advance.

James.

20220208_134547.jpg

20220208_134604.jpg

20220208_134656.jpg

20220208_134718.jpg

Link to comment
Share on other sites

5 hours ago, JamesRoss said:

If that bezel is removable I'd like to get it off so I can thoroughly clean and polish the case... and touch up or re-coat the bezel.

I'm at a bit of a loss. I can't see a way of pushing it out from the inside as the channels for the pushers and stem intrude into the watch body.

Seiko fixed bezels can be removed, but in practice unless there is a compelling reason i think is better not to do that. You need a precise aluminum die with cuts to clear the tubes.

Good buffing and polishing work can be done with a small wheel, besides these are utility watches with some character and I think they deserve to carry some signs of their adventures as opposed to overpolishing.

Link to comment
Share on other sites

Hi JDM.

I thought as much. Thanks. I have already got the dremel at the ready....

Residual question is... how can I remove the crystal? The chapter ring impinges on the diameter of the crystal by around 4 millimetres all round. Will ot be OK to use a smaller diameter die?

I guess it doesn't matter too much if I break and have to replace the crystal....but looking at it the chapter ring is held in place by the bezel... hmm....

Thanks for your advice... very grateful.

Take care.

James.

Link to comment
Share on other sites

11 hours ago, JamesRoss said:

I guess it doesn't matter too much if I break and have to replace the crystal....but looking at it the chapter ring is held in place by the bezel... hmm....

You must not press on the crystal neither on the chapter ring, only on the thin rim of the bezel that is exposed in the case. That is why the die must be precise. Once the bezel is removed the chapter ring will be free also.

Link to comment
Share on other sites

It'll be fine to press on the crystal a couple mm in with a slightly smaller die, unless it's already cracked.  If the chapter ring is metal, I've not had a problem pushing on it to press out the crystal.

You might need to remove the pushers, it depends on how big the inside of the bezel is.

The chapter ring might be trapped between the case and crystal, or between the case and bezel.  I.e., it may or may not come out with the crystal. I can't tell from the photo.  Bit blurry.

Getting the bezel back on straight can be a lot harder than getting it off.

Link to comment
Share on other sites

28 minutes ago, xyzzy said:

It'll be fine to press on the crystal a couple mm in with a slightly smaller die

Correct, but what the OP intends to do is to remove the bezel for polishing. In that case the crystal can be left in place. 

 

28 minutes ago, xyzzy said:

You might need to remove the pushers, it depends on how big the inside of the bezel is.

Not only the pushers but their tubes and the crown tube also, as the OP had noted. Which is why the die should be cut instead, to avoid messing with these.

 

28 minutes ago, xyzzy said:

Getting the bezel back on straight can be a lot harder than getting it off.

Correct, and it may have a gasket which is easily pinched,  then one ends with a problem bigger than the initial. From that my initial advise, if ain't broke don't fix it. 

Link to comment
Share on other sites

9 hours ago, jdm said:

Not only the pushers but their tubes and the crown tube also, as the OP had noted. Which is why the die should be cut instead, to avoid messing with these.

I've never had to do this to get a Seiko bezel off.  The pusher/crown tubes aren't that long.  On a large case, the pushers will just have long ends.  I think the long unsupported length past the tube makes them weak to bending.

On a small case, a 30mm die with a few grooves for the tubes will work.  If the bezel ID is greater than the diameter of the case inside, then the rehaut ring will be trapped by the bezel and one can press on that.

If I was going to polish the bezel, I'd want to remove the crystal.  One reason is to protect it.  But another is so I can grab the bezel with something on the inner diameter and spin it to polish.

Link to comment
Share on other sites

4 minutes ago, xyzzy said:

I've never had to do this to get a Seiko bezel off.  The pusher/crown tubes aren't that long.  On a large case, the pushers will just have long ends.  I think the long unsupported length past the tube makes them weak to bending.

On a small case, a 30mm die with a few grooves for the tubes will work.  If the bezel ID is greater than the diameter of the case inside, then the rehaut ring will be trapped by the bezel and one can press on that.

If I was going to polish the bezel, I'd want to remove the crystal.  One reason is to protect it.  But another is so I can grab the bezel with something on the inner diameter and spin it to polish.

You'll see from the photos I managed to muddle through. All part of the learning experience

Cheers

James.

Link to comment
Share on other sites

I took the crystal out and found this was the only thing holding the tachymeter ring in, behind a metal spacer. Once I stripped everything out of the case I gave up on trying to remove the bezel and just gave everything a really good clean. I took out the worst dents / scratches with careful sanding. Took the bezel back to bare metal (the pdm coating was horrible). 

I then polished the watch body, protected the polished surfaces with heat resistant tape and gave the bezel a brushed finish, sympathetically leaving evidence of the watch's previous hard life.

I polished the crystal using increasing grits of emery paper (dry, then wet) from 1000 to 10000 grit, finally a polish with glass polish.

I gave the back a brush finish.

I greased the o rings and seals.

Then patience and fun was to be had replacing the pushers (installing the C clips... ha ha) eventually I found the best technique involved constructing little rodico 'caves' to catch the little b***ers when they pinged off).

Chapter ring and crystal went back smoothly. I had to spend a bit of time straightening the battery terminals and the rear plate of the movement as the previous owner (presumably a gorilla) had changed the battery simply by ripping out the old one and shoving in a new one.

The whole exercise was simply a learning / confidence building exercise. I'm quite happy with the end result. There was a 50% chance of failure.

New leather strap on order which is probably more in keeping. I don't think even my meaty wrists will cope with a 22mm metal strap.

You may have missed the images.. here's the 'before and after".

Screenshot_20220209-184557_eBay.thumb.jpg.847b6fde9a370fb051ffbdb31af7da74.jpgScreenshot_20220209-194913_Chrome.thumb.jpg.32e5d0ac45ae3218d45ceebfdecd8313.jpg

 

Link to comment
Share on other sites



  • Similar Content

  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • Hi Bob, Welcome to the forum and thank you for your service.  I would never try to discourage you from getting into this wonderful hobby/profession, but please be aware, it does not cost just a few dollars to get into watch repair.  Tools are expensive and in many instances the cheap knockoffs are worthless, especially when learning.  You can get the tools needed to disassemble, clean, inspect, reassemble and lubricate a watch without spending thousands, but as soon as you start getting into task-specific tools, there are so many and they don’t come cheap.  My suggestion is to start with the basics required to disassemble, clean, inspect, reassemble and lubricate only, and build upon that gradually as the need for other tools arises.  The advice above regarding starting out on working movements is gold. Many of the non-running watches on eBay have been bought, tinkered with, deemed too difficult and then sold again, often with more damage done each time.  Without experience, you clean and service a non-runner and it still doesn’t run. What now? Troubleshooting is difficult as a beginner. This can become very frustrating.  I would encourage you to buy a working movement, and learn to strip and service it. If it isn’t running afterwards, you know it’s down to you, and as long as you didn’t damage anything you know that the parts you’ve got can form a ticking watch. An excellent movement to start with is the ETA 6497 clones from China, such as the ST36. They’re not expensive, and although it finds use in some larger wristwatches, this movement was originally designed for use in pocket watches, so everything is larger and easier to see and handle.  Once you can service a new ST36 and have it running better than it did when it arrived, you’re definitely ready to step up to working vintage watches and then think about repair of non running or poorly running watches.  As far as cleaning solutions go, you will not do better than the commercial watch cleaning and rinsing solutions that are available. You’ll find plenty of suggestions for home brew cleaners online, but the professional products are superior and you want to give yourself every advantage you can, especially when you start working on vintage movements containing hardened decomposed lubricants and often years worth of other dirt and dust. Alcohol is ok for cleaning or rinsing movement parts that don’t contain any shellac. The pallet fork and roller table contain jewels secured with shellac and will tolerate a rinse in alcohol but not prolonged exposure. Methanol dissolves shellac faster than ethanol, and isopropyl alcohol dissolves shellac slower than ethanol. Just in case you don’t know already, the radium on the dial (and likely the hands) of your Dad’s Elgin is highly radioactive. It is safe enough when safely contained within the watch case, but the moment you open the watch and especially when handling the dial or hands you must take precautions against inhaling or ingesting any radium.  Best Regards, Mark
    • I have both sets and use the K&D 99% of the time.  Yes, you have to be careful with the pin.  I use a screwdriver to carefully release the pin from the spring.  Some skill is involved.   I have also modified/replaced the pins in the arbors as necessary.  Yeah, you would think a tool would not require modification, but such is the world of watchmaking.  There is no perfect tool.  Each watchmaker must the tools to his skill, or vice versa.
    • I have the 8-11mm K&D but it doesn't do a great job with modern mainsprings, or I have had terrible luck. The arbor pin protrudes too much and I have damaged more springs trying to disengage the arbor than I have successfully wound and inserted. It seems easier to use with old carbon steel springs. My Watchctaft set gets far more use, though I have to get creative to wind left hand springs
    • It depends on what the gaskets are made from but silicone lubricant should work.  Spray or rub on a generous amount, put in a sealed bag and wait a couple of days.  Test for softness and wipe off the excess.  
    • For hardened gaskets, an experienced watchmaker told me he usually found heat to be the best to soften them up. I tried that on a '70's Tissot where the gasket had turned to essentially epoxy to no avail, but eventually got it off with a 5700 case back opener using a crowbar for leverage to turn the wheel.
×
×
  • Create New...