Broken yokes - approach for repair and sourcing parts?

[GrahamT]

I'm new to watch repair, and recently I've been working on Helbros watches (with the crazy variety of movements to be found in them). Yesterday I had the mildly soul crushing experience of going to the "to be overhauled" bin and finding THREE movements in a row with broken yokes. Two of them are shown below - one is a FHF 28 17-jewel movement, and the other is a Fontain/Helbros 6-jewel movement. 

This got me wondering about how a pro would approach the repair. I don't have a huge stash of parts yet, and pinning down specifications for keyless works parts seems really challenging (they all seem slightly different). Is the best bet to keep searching around for donor movements? Would a pro ever braze the yoke back together? 

As an interesting side note I was searching around and found the FHF 67 movement (shown below) for sale on eBay, and that one also has a broken yoke. Guessing that certain movements are more prone to this problem than others.

Any thoughts on this one would be much appreciated!

[anilv]

It is a part that can be made but you will need good steel stock (hacksaw blades), some watchmaker grade files and drills and a way to remove the temper of the steel so that you can work it, and a way temper the steel once you're done. For these flat parts the idea is to start with a thicker piece of metal (hacksaw blade) and do the holes and critical areas (like where it 'clicks') then get the shape (outline) correct and finally thin the piece down.

Generally speaking its not something for the beginner but I don't know how high you motivation (or stubborness) levels are as this will be the critical requirement.

If you do try this post your progress here! Best of luck.

Anilv

[GrahamT]

Fantastic - really appreciate the fast response and the DIY approach. I definitely have hacksaw blades and pattern files, so probably much faster than lurking on eBay! Will let you know how it goes.

[watchweasol]

Feeler gauge steel also works in these cases. as they come in a variety of sizes you mat be able to get something close.

[jdm]

15 hours ago, GrahamT said:

This got me wondering about how a pro would approach the repair.

If the part absolutely can't be found (I don't think that's the case here) then as mentioned, by making a new one. Check the featured post below where a beginner made an excellent job.

 

[Nucejoe]

  FHF parts can inexpensively be had.

 

[GrahamT]

Thanks all for the help! Great suggestions. Turns out I have an old set of feeler gauges that I could use for this. Will post the outcome and let everyone know how it goes.

[LittleWatchShop]

This looks like a fun project.  Seems to me, a good approach would be to glue the broken part on the new material and that would give an accurate template to file to.  Never done it, of course, so maybe there is a problem with this idea.

The other thought was to use a laser cutter to mark the design prior to filing.  This would be exciting for me because I would get to buy ANOTHER tool!

[JohnR725]

20 hours ago, GrahamT said:

This got me wondering about how a pro would approach the repair.

A professional I assume you mean a person who is attempting to make a living repairing watches? We figure out what part they need an attempt to order it versus making one because making one is going to require time and effort. On a watch like you have which doesn't look expensive attempting to convince a customer that the parts going to cost a lot of money to make is going to be problematic to get that money.

1 hour ago, LittleWatchShop said:

The other thought was to use a laser cutter to mark the design prior to filing.  This would be exciting for me because I would get to buy ANOTHER tool!

Even though the price of I assume you mean fiber laser because it worked perfect for this has come down to between three and $4000 on eBay what about getting an EDM machine? Problem with the laser is it tends to get things hot sometimes depends on how fast are doing things. On the other hand a wire EDM machine doesn't get hot and the part could be already nice and hard in tempered when you're cutting it out and not suffer the heat of the laser.

20 hours ago, GrahamT said:

(they all seem slightly different).

Interesting you should mention that? If you have the proper reference books such as bestfit Which I'm sure someone can tell you how to download it for free. What's interesting about these books is they have something that's called the fingerprint system in other words a way of identifying the watch you have from components and I will snip out an image to show you what I mean specifically the setting parts. So up until relatively modern whatever that is all the setting parts were uniquely different. So if you had a unknown watch and we knew the diameter size you can look up the setting parts and figure out what the watch movement is. But that doesn't mean that all the parts are really unique in that lot of time the watch will have a base caliber and parts will interchange.

Then from the path of this discussion it looks like you really have your heart set on making the new parts so I'm not going to discourage you from that or take the time to look up the parts for you. But in the future if?

20 hours ago, GrahamT said:

THREE movements in a row with broken yokes. Two of them are shown below - one is a FHF 28 17-jewel movement, and the other is a Fontain/Helbros 6-jewel movement. 

Three movements one of which you've identified the other one I'd have to look at the picture and the third one is? The reason I'm pointing this out is in the future if you want us to help you to find a part it be really nice if you list the movement numbers.

 

 

[GrahamT]

Many thanks again for the help on this one! In the spirit of learning I'll keep going in both directions, trying to source a part while I make a replacement. The references above are great - clearly I need to keep working on identification and cross-referencing skills with the catalogs and various other sources. Looks like a chance to revive the old army identification skills with those decks of cards that showed silhouettes of planes and tanks (now adapted to watch parts).

A rough-in of the replacement is shown below. I've filed and shaped it a bit more but may start over to give it another try. Quick summary of the process:

• Started with metal from a feeler gauge
• Punched the screw hole
• Attached the broken part to the steel with Shoo Goo
• Roughed in the shape (very slowly) using a cutoff wheel on a Dremel
• Shifted over to various files for the final shaping

Will keep everyone posted on the outcome! 

[watchweasol]

Coming along nicely, just take your time you are 90% of the way there,  well done

[GrahamT]

Follow up on this one to round it out. Big lesson learned was that I should have completed the disassembly on the movement first! I ended up finding more issues, so in the end it wasn't worth the trouble to try to salvage this specific movement without sourcing a donor. Very logical to strip down the movement completely to see the overall situation, so I'll take that approach going forward.

I'm also building my sourcing skills with all the catalogs and whatnot that are out there. Clearly this is a critical skill, to be able to sort through all the manufacturer/distributor stamps, the reference numbers, the movement variations, etc. 

Thanks to everyone for the help on this one!