Jump to content

Landeron 248 setting eccentric studs


Recommended Posts

Hi guys,

I wrote a set of five lessons for my second year students regarding the Landeron 248 chronograph watch, which incidentally we are meeting tonight. They are going to be polishing pivots and pinion leaves of their 248s, before putting the movements through the cleaning machines.

This is number one of five. I posted number two of five the other day HERE

 

There are seven eccentric studs on this movement, so understanding what the studs do, how to set them, their actions and interactions with other parts of the chronograph mechanism is vitally important.

I found there is very little out there on the internet to help understand the principles of these eccentric studs, especially video content to show various faults and alleviations, so I put together quite detailed walkthroughs of various complicated movements usually consisting of 15 to 18 hours of learning/servicing in the workshop per movement/module

With any watchmaking, especially with complicated work, only make one adjustment and measure the results, if any. Be methodical in your approach.

The lesson was originally in PowerPoint and I had to convert it to PDF to post here, so a lot of the video content won't play, but the PowerPoint version is in my cloud storage here.

https://docs.google.com/presentation/d/10KJJ58P0v2BglKZSilIv9o69xBsbrQPI/edit?usp=sharing&ouid=107902587627140904870&rtpof=true&sd=true

You'll need quite a newer version of Microsoft Office (PowerPoint) so the video content will play, otherwise it won't. I hope you find this lesson useful and begin to get a better understanding of how to set eccentric studs. Sometimes you'll come across a stud that is too loose, or even too tight. Usually if one is problematic it will be because it is loose. This can't be left, as the stud will turn whilst the chronograph is stopped, started and reset, throwing the chrono mechanism setting off which could lead to the movement grinding to a halt. Don't fool yourself in thinking it will hold. Either a replacement stud is fabricated to suit the enlarged hole, or the hole can be closed up. In turning and setting the eccentric studs prior to disassembly of the movement, we are able to set the chronograph mechanism, especially the minute register mechanism correctly and test for any faults, such as a bent wheel over fourth arbor, or incorrect depth of the dart tooth with the sliding gear, or a mis-set minute runner jumper spring, to name a few possible faults and mis-settings. Also in turning these eccentric studs we can gain a 'feel' for how tight they are in the mainplate or bridge. The more they are turned the more the chance of the stud becoming looser increases. So once set correctly prior to cleaning, the less chance they will need setting once the chrono mechanism is assembled, only if a stud isn't tight enough in its setting in the first place.

This is for setting Landeron 248 eccentric studs, but once an understanding of their uses and actions is gained through theoretical aspects together with practical application, then this skill and knowledge can be used in most vintage chronographs to set their eccentric studs and even in modern timepieces where you'll find very few eccentric studs, such as an Omega Speedmaster or Tag Heuer Calibre 01 chronographs

Enjoy!

 

Lesson 22. Landeron 248 Chronograph.pdf

  • Like 4
  • Thanks 1
Link to comment
Share on other sites

1 hour ago, Jon said:

Hi guys,

I wrote a set of five lessons for my second year students regarding the Landeron 248 chronograph watch, which incidentally we are meeting tonight. They are going to be polishing pivots and pinion leaves of their 248s, before putting the movements through the cleaning machines.

This is number one of five. I posted number two of five the other day HERE

 

There are seven eccentric studs on this movement, so understanding what the studs do, how to set them, their actions and interactions with other parts of the chronograph mechanism is vitally important.

I found there is very little out there on the internet to help understand the principles of these eccentric studs, especially video content to show various faults and alleviations, so I put together quite detailed walkthroughs of various complicated movements usually consisting of 15 to 18 hours of learning/servicing in the workshop per movement/module

With any watchmaking, especially with complicated work, only make one adjustment and measure the results, if any. Be methodical in your approach.

The lesson was originally in PowerPoint and I had to convert it to PDF to post here, so a lot of the video content won't play, but the PowerPoint version is in my cloud storage here.

https://docs.google.com/presentation/d/10KJJ58P0v2BglKZSilIv9o69xBsbrQPI/edit?usp=sharing&ouid=107902587627140904870&rtpof=true&sd=true

You'll need quite a newer version of Microsoft Office (PowerPoint) so the video content will play, otherwise it won't. I hope you find this lesson useful and begin to get a better understanding of how to set eccentric studs. Sometimes you'll come across a stud that is too loose, or even too tight. Usually if one is problematic it will be because it is loose. This can't be left, as the stud will turn whilst the chronograph is stopped, started and reset, throwing the chrono mechanism setting off which could lead to the movement grinding to a halt. Don't fool yourself in thinking it will hold. Either a replacement stud is fabricated to suit the enlarged hole, or the hole can be closed up. In turning and setting the eccentric studs prior to disassembly of the movement, we are able to set the chronograph mechanism, especially the minute register mechanism correctly and test for any faults, such as a bent wheel over fourth arbor, or incorrect depth of the dart tooth with the sliding gear, or a mis-set minute runner jumper spring, to name a few possible faults and mis-settings. Also in turning these eccentric studs we can gain a 'feel' for how tight they are in the mainplate or bridge. The more they are turned the more the chance of the stud becoming looser increases. So once set correctly prior to cleaning, the less chance they will need setting once the chrono mechanism is assembled, only if a stud isn't tight enough in its setting in the first place.

This is for setting Landeron 248 eccentric studs, but once an understanding of their uses and actions is gained through theoretical aspects together with practical application, then this skill and knowledge can be used in most vintage chronographs to set their eccentric studs and even in modern timepieces where you'll find very few eccentric studs, such as an Omega Speedmaster or Tag Heuer Calibre 01 chronographs

Enjoy!

 

Lesson 22. Landeron 248 Chronograph.pdf 9.08 MB · 3 downloads

Hello Jon, I  get this.

Screenshot_20240422_170022_Adobe Acrobat.jpg

Link to comment
Share on other sites

I opened it too, and can asure that it is good and thorough.

I can add something little for the minutes counter adjustment (will use the terms from this presentation) - sometimes is prefferdd that the T-line will be slightly tilted as to alow little bigger gap between the the tooth A and the dart tip, and the gap of C tooth is reduced to almost 0, as shown on the picture (from manual for 3133)

Untitled44.thumb.png.5e070a684d5a91fcc3f99c21be9fc4d7.png

Also, there is one more option, offering the same result as the changing lenght of the dart or slope of the hammer head - this is changing the position of the heart on the minutes counter wheel. Sometimes just turning hte heart upside down changes slightly the wheel position and thus one can choose the better between the two. Then, the heart position can be totally changed by making new hole for the screw that fixes the heart

  • Like 2
Link to comment
Share on other sites

If you have no Powerpoint at Hand (but Libre-Office or whatever..),

to get Access to the Videos in the pptx, make a Copy of the File, rename it to blabla.zip and unzip the File.

Now in the Folder ppt/media you have all Pictures and Videos......

 

hope this helps some of us

regards,

Ernst

  • Like 1
Link to comment
Share on other sites

On 4/22/2024 at 7:42 PM, nevenbekriev said:

I opened it too, and can assure that it is good and thorough.

Thank you. I spent a lot of time on that.

 

On 4/22/2024 at 7:42 PM, nevenbekriev said:

sometimes is preferred that the T-line will be slightly tilted as to allow little bigger gap between the the tooth A and the dart tip, and the gap of C tooth is reduced to almost 0, as shown on the picture (from manual for 3133)

It never ceases to amaze me that there are so many slight adjustments that can be made to the chronograph mechanism through setting the eccentric studs to get them all to a concerto, like an orchestra with everything in time and to its most optimum. Understanding that setting one stud to the desired effect may throw another out is the fun of working on vintage chronographs.

Great pic of the 3133 dart tooth interaction and tilt of the tooth. I love working on 3133s. Slightly better than the 7733 in my opinion and you get a date at 6!

  • Like 1
Link to comment
Share on other sites

So much work has gone into this! Thanks again @Jon. I will go back and check my adjustments from last weekend.

A few questions for you, if you don't mind.

In the reset position, I can understand the problem if the gap between the hammer and the minute counter heart is too big (slide 77) but what is bad about both hammers being in contact with the cams (slide 76)?

I read somewhere that Landeron recommended grease on the runner cam, but the minute counter heart should be dry. Is that so, and why?

How many tads in a ligne?

Link to comment
Share on other sites



  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • Thank you for this post. Adding on to it, I've done a little digging trying to get the most bang for my buck. So I really wanted a set that had a base. You can buy the screwdrivers for around $33 usd 10 Piece Screwdriver Set. The base is around $32 usd Rotating Screwdriver Base (Grey) plus $20 in shipping, with tax you are looking at about $90 which is an excellent deal for what you get but I still didn't want to spend that much. I saw that they had the 9 piece set w/ base for $59 usd 9 Piece Screwdriver Set W/Base and I had a 'welcome discount' and got a matching 3mm screwdriver for 99 cents. 3mm Screwdriver. (without the discount the screwdriver is $6) With free shipping my total was $66.55 usd. So, I saved about $24 to go without a slot for a 3mm screwdriver. I'll take that! I hope this helps anyone looking to save a buck or two. Also, this corrects the issue of the orange 1.8mm screwdriver. 😉
    • No hex wrench needed there. Screw driver in case of AS1475 or just push the poinst down in case of Poljot2612.
    • Well, what is written here can't be explained with the wear of the winding/sliding pinion. Probably it is some kind of delusion from You side. But it prevented the people from pointing the reason of what is happening. Otherwice, this kind of wear is one of the common problems of winding works in watch movements. It meets often in old or cheap movements, or particulary in negative stem system pocket movements where not proper adjustment of the sleeve that guides the stem is done.  
    • Well I started with the rotor, then I couldn’t find how to let down the power so I removed the balance then found the click and let down the power.  After that I took apart most of the watchmaker side with the exception of the hour wheel which was still held by the cannon pinion and the hour wheel bridge which I put back when I realized the above.  I then went to the dial side and removed the cover plate. There were a few flat part which I had no idea what they were or where they should go as they got stuck to the plate by lubrication. Luckily I found an assembly video of that movement by the watch smith and he explained that those parts are part of the quick date setting system.  So I put them back in place and took a picture before continuing the disassembly  One thing I keep hearing in video or seeing in forums is that Chinese movements are often not lubricated. WellI can tell you the one I have is drenched in oil. Everything is stuck by capillary action on the dial side and I see pools of oil under each wheel.  Quite a bit of lint stuck to the oil too Just realized there were 3 screws, 2 holding the yoke maintaining plate and 1 holding the setting lever jumper.  I hope they are the same because I mixed them up and I can’t tell them apart.    Done with the disassembly and done for the day. For the reassembly I have a video to follow which is great because the dial side is quite complicated and I couldn’t take good pictures of the components position as several got stuck on the plate by lubricants as I lifted it so I never saw where they were supposed to be. 
    • I have one, but I don’t have the hex wrench to remove the stems. Does anyone know where I could get these in USA? Thanks in advance for any advice kind people! 
×
×
  • Create New...