It's been a busy couple of months and a while since i last posted here ( apologies regular readers ) but with over 12 chronographs to get through this past 8 weeks its been hard to find the time :)
In for inspection and service is this lovely vintage chronograph by Butex, the watch was running reasonably accurate but i was informed the chronograph would stop at 58 seconds every time. After a short run on the timegrapher at full wind it was clear something was not right, the amplitude was well below anything that could be regarded as accurate ( 130 Degrees ). With such a low reading it was clear the mainspring was not able to power the watch sufficiently but also that dry oil or lack thereof may also be a contributing factor.
Before we can look at the chronograph and its function we need to get the movement stripped down, cleaned and ready for base movement assembly, if the base movement runs sound then we know its something in the chronograph assembly causing issues.
With the movement stripped down and cleaned it was time to get the base movement together and see how it ran. Starting with the base movement we can tell whether an issue lies in the base or the chronograph assembly, a simple process of elimination. I must admit i do like the pink gilt finish over the standard nickel plating so its always pleasing to see it come out so clean after a good run in the machine. >>
With the base movement together it was time to fit pallets and balance and wind her up ! After a good wind the movement sprang into life but now with a good healthy amplitude of 300+ degrees, the addition of a new mainspring helping out of course ( original was broken at hook end ). With such a healthy base it was time to put the chronograph together and see where the problem was hiding, whilst disassembling the movement i did note the minute recording wheel was very stuck in so this would be one place to look. >>
Whilst assembling the chronograph it is important to note the minute recording wheel does not require lubrication, however at some point in the past this was done and the oils had become dry and tacky. Dry tacky oil can be stubborn to remove even after cleaning through a machine, in this case the pivot holes for the minute recorder had become victim to just such gunk and a hand cleaning would be needed.
The chronograph was assembled and depthing of wheels checked and adjusted but with the movement stopping at 58 seconds the only thing left was the minute recording pivots. After using an oiler soaked in essence to clean the pivots the minute recorder was refitted and the chronograph ran its full cycle. It strange to think a watch can be stopped by such a small thing ( as well as broken mainspring ) but the attention to detail is what watch repair is all about.
With the movement running sound there was only one issue left to overcome and that was to fit the correct stem. On reassembling the base movement i noticed how the stem was not quite the right fit and that it lacked the rear end shoulder which supports the stem in place. With a new stem comes a new crown and fortunately i have plenty of NOS crowns from the same period so this was no problem at all to remedy. >>
As a recap the movement arrived with low amplitude, chronograph stopping at 58 seconds, a broken mainspring, dirty pivots, and lack of good lubrication and topped off with incorrect stem. Now after some tlc the movement runs very well and the chronograph is functioning normally as well as a nice new correct stem and crown :)
The watch together again and timing is as good as it was when it was made :)
Thankfully this chronograph can return in full working order and be enjoyed again by someone who no doubt will appreciate it :)
I realise there has been a long break between blogs but there will be more coming in the next few weeks to keep you entertained. There will be a special look at an unusual ETA 7750 chronograph as well as hopefully the restoration of a vintage split seconds chronograph from the second world war. Also look out for up coming videos on my YouTube channel which should be produced soon ( time being the enemy here ha ha ).
Hertfordshire based watch restorer. Follow my blog for new watches under restoration/repair