Inside the Seiko Cal. 4s24 hand wind.

Inside the Seiko Cal. 4s24 hand wind.

Joined: July 19th, 2008, 3:38 am

June 24th, 2009, 6:18 pm #1

Orignally posted on SCWF on June 4 2002.

First, let preface this by saying I took a lot of pictures. But, most didnt come out the way I wanted, some of the things I really wanted to highlight, I`ll just have to explain. Theres only about half of the scans I actually took here.

The watch,being just purchased by the owner came to me for a simple regulation. Unfortunatly, the watch would not put out a reliable rate. It kept going up and down, way to much for me to get a grip on what it was running at. It was at this point that I decided to run the beat trace, and it became clear that the watch was going to need a service.

This beat trace shows why the reading on the timing machine was so unstedy. You can see thats its rate is actually going up and down. The roller-coster affect shown here is primarily a result of gumbed up and dry oil, It shows a unstable power flow through the intire train, resulting in a increase and decrease of amplitude, hence the up and down pattern. The watch could`nt be reliably regulated. Even if this pattern equaled out at some point, it could change on a moments notice.

I have found that unlike the 7s and 6000 series calibers, the higher running and tigher tolerances of the 4s series do requier more servicing and maintanance.

The first thing that I noticed when I removed the balance cock was the color and quality of the jewels. This is often overloooked in fairly inexpensive watches (this watch was purchased second hand for 300 us). Its a delight to see that Seiko has matched the color of each and every jewel, and that the jewels themselves are a beautifull deep red color, through and through the movement, as will be shown in the following pictures.

Also, I found the finishing of the plates astonding for a watch so resonably priced.

The frist sign of quality I see when disassembing a movement is the pallet, the escape wheel, and the pallet jewels. The remarkable finish aplied to the top of the pallet fork, was again, a delight in a 300 dollar watch.

The pallet and escape wheel really shine when removed from the movement. Below we can see the "black polish" imparted to the pallet fork. Also note the color of the pallets.

Now we`re going to turn our attention to the escape wheel. While there was a slight graining to the rim and arms of the wheel, the working surfaces show a perfect polish. The polish of the working surfaces here are critical to the performance of the watch, and the amplitude.

Above we see the polish playing in the light. The foot of the touth on the right hand side reflects the light, while the other teath show the "black polish".

And in the photo below, we can see the bevel to the teath. This bevel will reduce the friction of the teath on the pallet jewels, alowing them to slide off the teath easier. Although not as magnified as I would like, the pinion end (extream right end of the wheel) can be seen in the light as being nice and polished, with the appropriate flat end, because this pinion uses a cap jewel, both top and bottom.

In the image above, we`re moving along with the disasembly of the movement. The top plate has been removed, and the train is visible. Although the bottom plate shows no decorative finish, it is still remarkable in its uniformity, and cleanlyness. The long arm going to the midle of the movement is the tension spring for this calibers center seconds. These watch use a somewhat indirect center seconds drive, and will show a little "float"in the second hand when hacked.

Here is a another view of the spring, please forgive that I didnt have it in focus. I was trying to get a shot of the working sufaces here, but sadly I belive my concern was with the watch, and not my photography.

With the movement completly disassembled, I turn the bottum plate over.

Again, in Seiko fashion, there is no decorative finish, and yet the plates uniformity and cleanlyness, are decoration enough, for me.

One of my few nit-picky points with this movement can also be seen above. Seiko has jeweled the top of the barrel arbor, but here, where it is unseen, they chose to bush it. I`m still getting over this, as it does border on dishonesty.

The peculiar thing about this movement, is that all of the handwinding parts are located under the dial. These will be pointed out as we go along now. The movement has been through the cleaner, and I`m in the process of putting it back together now.

Above the keyless works and the barrel wheel have been installed. The barrel wheel click is highlighted in red, at the top of the scan. The rachet wheel (in green) is spring loaded, and rachets when it is forced upwords by the the intermediate wheel (not show, in the blue circle).

With the winding works cover installed, we see the intermediate wheel, and can see the power flow through to the barrel when the watch is handwound.

Ohh, the big hole on the left?

Because this is the base caliber for so many watches, this hole is machined to accept the day and date jumper wheel, if it were used. This watch is a simple center seconds, three hand dial, with no date or day, and this is not used.

With the movement put together,wound and the

escapement in, I look at the locking. Although its not quite as light as I would prefere, its does show a bit lighter then the lesser grade calibers.

There is a compromise here, as too little locking will lead to a watch thats not safe, in that the pallet can come unlocked with a jolt and foul the roller. Like wise, when the locking is too deep, the energy used by the balance as its trying to unlock the pallet can reduce amplitude. Where this line is drawn between the two is better left to engineers, and escapement designers I think (at least for now :^)).

The last point I wanted to make was what Seiko has used in the curb pin assembly. You have heard me state befor how Seiko uses a unique moveable curb pin, to alow easy adjustment of vertical positional errors. Try as I might, I was unable to get a real clear shot on this pin, and its simplicity of design. Needless to say, the pin is atached off-center from the centerline, thereby moving into and away from the fixed pin when the arm is moved. This is most usefull, again, in adjusting the watch for errors that present themselves in the vertical positions, when the weight of the spring can force it into and away from the pins. Used properly, as can be seen in the following timing scans, the watch can preform remarkably well in the vertical postions.

And now, with the dial and hands on, comes my only other nit-picky point. Although I belive the main hands are traditionally heat blued, the center second hand is obviously done differntly, and does not match the main hands. I found this a shame when considering the rest of the atention to detail, but this could result from Seiko not wanting to mess with the odvious warpage issues such a thin hand would have.

Now, with the watch completly assembled, and run-in for a few days, comes time to see what this watch is capable of. To be honest, I did not expect such preformance.

Above, the beat trace befor regulating shows quite an improvement over the rollercoster that the watch produced befor servicing. The lines are now running paralel,and in a straight line, now I can regulate it.

After regulation, a rate trace was preformed, and the results are to this watchmechanic, ASTOUNDING.

Absolutly excelent proformance, for a watch thats not that expensive. In fact, I belive if this watch was made by a swiss manufactor, with this kind of performace, its cost would be considerable. The dial up and down and crown down rates are indentical. In daily wear I would expect this watch to go days befor any noticable change in timing was evedent. The closeness of the last two vertical possitions is exemplary, showing hardly a 5-6 second difference between the two.

In conclusion, I belive that in the watch world, these watches represent a bargin among and BEYOUND bargins. The preformance of the finished watch is simply unatainable for even much more.

In fact, the owner emailed me a few day after he had been wearing the watch. He wanted to know if it was my work that had the watch running so well. I had to tell him the truth. My work only built upon the attention and detail of the manufacturer. The watches performance is mostly atributed to the care and detail in the manufacture of the watch. Such things as pivot finishing, uprighting, colleting, depthing and point of atachment all need to be adressed at the production level, and it would appear that not only did Seiko do their homework, but they implemented that homework very well indeed in the production of this watch.

Yes, I own three watches based on the 4s series,and in daily wear, they are extrodinary

Hope you enjoyed the artical. Any questions or comments gladly accepted.

Best regards,


Seikoholic #1
Specializing in Seikology, Seikotherapy, and other Horological Dis-ease.
Made in the U.S.A.