First Project Already A Bit "Sideways"

[DDean]

I decided that it was time to tackle the piece that I'd set aside as my first project.

The subject in question is a Gruen Veri-Thin pocket watch.  It winds and "runs".  On the time grapher, it has reasonable amplitude (240 or so depending on the position), but was loosing close to a minute a day.  The stem also has the annoying tendency to just come out when pulled, which makes it super hard to set the thing. 

As with many things this one started sideways and just got more so.  I was able to overcome the mangled "tab" on the back case cover (a well placed, very sharp knife enabled me to get in when I couldn't get a purchase on the mangled tab with a case knife.)   I was then sort of shocked to find that one side of the dial was held down with some sort off tape or adhesive material as someone had broken the dial foot screw on that side and left the broken screw in the mail plate.

The loose stem does in fact seem to have been a poorly tightened setting lever screw, but I'm afraid there may still be gremlins in the keyless works.  While I was able to get the stem to stay in by putting everything in the right place and tightening the setting lever screw (before I took it all apart for cleaning and inspection), it just didn't seem to all sit right.

The final gremlin showed up when I was taking off the lower cap stones for the balance and escape wheel (yes the Gruen 380 seems to have a cape jewel on the escape wheel).  The balance stone came off fine (but that in fact is the smallest screw I've ever seen.  When I turned the movement around to get the one off the escape wheel setting, I found that the screw head had been mostly sheared off.  After some reading and looking at what I had, I decided to try and tease what was left of the screw out of the hole by nudging what was left with the corner of my smallest screwdriver.  After 20 minutes or so, I was able to get the remains of that screw out.

The picture I'm including of the disassembled movement was taken before I got the second cap stone off, so in the picture, it's still attached to the main plate (for those looking carefully, you'll only see the one cap setting in the pic.)

Now I'm left with:

• A broken dial screw inside the main plate that needs to come out
• A broken cap stone retention screw that I have in my parts tray, but that is strictly useless and needs to be replaced.
• The need to get another dial foot screw

I'm contemplating solving the first problem by soaking the main plate in an alum solution.  I think the main plate is brass and shouldn't be affected, but I have not been able to confirm.  This seems like the easiest option as I can't really access both sides of the screw to use the pricey Bergeon tool (which I don't fancy buying unless I have to.)

I have located a couple of donor movements and have questions out about whether or not the include the dial foot screw and prompting for pictures of the dial side so  evaluate the cap stone settings.  I've also found that a supplier in this country does have the cap stone settings, but isn't overly clear about whether the screws are included.

Are these the types of things that one can scavenge out of assortments or is it best to just grab one of the donors assuming that they look like they have what I need?

 

[ColinC]

Personally I would salvage the missing screws from some donor movement.  I also bought a random selection of screws "Assortment of Stainless Steel Watch Screws" for next to nothing. 

As for using an Alum solution - I had great success with that removing a rusted stem from a stainless steel crown.  The best piece of advice I read on doing that was to keep the solution warm so that the reaction didn't take weeks!  I did it in a couple of hours with the solution in jam jar and the jam jar in a saucepan full of water which I left on an induction hob maintaining about 60C in the Alum solution.

[RichardHarris123]

Screws are available as below. 

[Waggy]

Here is another option, if you have the patience to sort through the parts you usually find 50-100 screws as well as some other cool stuff. Most times I get an order from these guys I get a 250g box, takes a few days, but end up with hundreds of spares and all you need is for one of them to be useful and it pays for itself. Also helps hone your tweezer skills!

[nevenbekriev]

Hi Dean,

The solution with the alum for the broken screw is good and is generally used by watchmakers from many years, but You have to take off ALL steel parts from the plate. In some movements, the post for the minute wheel, for example, is made of steel. Deeping partly the plate works too, but some marks may left on the line where the solution doesn't cover the plate. Heating the solution is needed to accelerate the process.

With the years, a rich collection of screws gathers and then finding the needed screw is not a problem. But till then it will be helpfull if You get some assorted screws lot. The other option is making screws. This is usually for the ones with specific form and sizes that doesn't meet often. But the skill of making screws is something that will never be unnecessary

[HectorLooi]

Could you post a closeup photo of the broken screw that you are trying to remove so that we can better advise you.

[Neverenoughwatches]

16 hours ago, Waggy said:

Here is another option, if you have the patience to sort through the parts you usually find 50-100 screws as well as some other cool stuff. Most times I get an order from these guys I get a 250g box, takes a few days, but end up with hundreds of spares and all you need is for one of them to be useful and it pays for itself. Also helps hone your tweezer skills!

I love these boxes, fantastic for spares, mostly Indian, chinese and Russian but exactly as you say scott, you only need to pick out a couple of pieces and they've paid for themselves. 

[DDean]

11 hours ago, HectorLooi said:

Could you post a closeup photo of the broken screw that you are trying to remove so that we can better advise you.

I will try this weekend.  I've tried several times with my cell phone and it's just too small and recessed to get a good picture.  I need to get my macro lens and tripod out and then figure out how to get enough light down the hole in the side of the man plate to  actually show the top of the broken screw.

I appreciate the effort and will try and get that pic this weekend.

[Waggy]

On 5/16/2024 at 2:08 AM, DDean said:

A broken dial screw inside the main plate that needs to come out

Depending on how much of the screw is left, you may be able to screw it further in and it may fall out of the hole that the dial foot sat in. To do this I rough up the tip of the good screw and screw it in, often the rough surface of the good screw and the rough surface on the broken screw get enough of a bite to transmit the torque into the broken section and force it out the other side. Like I said the size of the broken screw needs to be in your favor, but you never know you may get lucky.... or if you get it moving you may be able to then back it out with a screwdriver taking a bite on the rough surface. worth a try

[DDean]

On 5/16/2024 at 2:10 PM, HectorLooi said:

Could you post a closeup photo of the broken screw that you are trying to remove so that we can better advise you.

For those who are, curious I broke out the macro lens and took a few shots.  I'm attaching four of them:

• Image 1 is from the watchmaker's side and generally shows the problem area.
• Image 2 is a detail view of the offending dial foot hole (called out with the green circle), the tip of the offending screw (orange arrow) and the blue line indicates the approximate position of what's left of the head of the screw (determined by using an oiler as a feeler gauge to transfer that measurement to the visible portion of the plate.)
• Image 3 is looking down the screw hole you can see the head of the broken screw at the bottom.
• Image 4 is the same, but with less contrast to give a better appreciation of the condition of that end of the screw.

I can almost convince myself that I can see the remains of the screw slot in the head, but I have to use alot of imagination in that exercise.

On 5/16/2024 at 11:23 AM, nevenbekriev said:

Hi Dean,

The solution with the alum for the broken screw is good and is generally used by watchmakers from many years, but You have to take off ALL steel parts from the plate. In some movements, the post for the minute wheel, for example, is made of steel. Deeping partly the plate works too, but some marks may left on the line where the solution doesn't cover the plate. Heating the solution is needed to accelerate the process.

With the years, a rich collection of screws gathers and then finding the needed screw is not a problem. But till then it will be helpfull if You get some assorted screws lot. The other option is making screws. This is usually for the ones with specific form and sizes that doesn't meet often. But the skill of making screws is something that will never be unnecessary

Heard and understood.  There does appear to be a steel locating pin that can be seen in the lower, right center of Image 1 (right "above" the oval shaped slot that is to the left of where the pinion/clutch parts of the keyless works nestle into the plate.)  As I don't see a way to remove that I'd have to keep it out of the solution and have even contemplated dropping a little paraffin on it to give it a "rain coat" of sorts.  As I missed that before I did the closeup photos, I feel that I'm going to be looking at this plate in much greater detail to see if there anything else I might have missed.

The screw assortments seem like a good acquisition.  The eBay seller who has the donor movements I was looking at never replied so I may just take a chance and get one of those as well a screw assortment.  They do seem like they'd be handy.  I have to confess that the idea of fabricating the needed screws appears to some deep part of my soul, I also have to confess that I do not yet have either the equipment, or the skill to use it.  Perhaps one day, but that day has not arrived (and I have alot of pricey bits and bobs that I will likely need to get along the way.)

On 5/17/2024 at 2:18 AM, Waggy said:

Depending on how much of the screw is left, you may be able to screw it further in and it may fall out of the hole that the dial foot sat in. To do this I rough up the tip of the good screw and screw it in, often the rough surface of the good screw and the rough surface on the broken screw get enough of a bite to transmit the torque into the broken section and force it out the other side. Like I said the size of the broken screw needs to be in your favor, but you never know you may get lucky.... or if you get it moving you may be able to then back it out with a screwdriver taking a bite on the rough surface. worth a try

I thought about this, but the dial foot screw doesn't seem to be wide enough to get the thing out if I could advance it into the hole.  I suppose that I could try and take it out in pieces (advance it as far as it will go, get in there with some sort of saw, take a piece off, walk it forward again, take another piece, etc) but that seems like alot of risk to the main plate. I need to examine the other screw to ensure it doesn't have a shoulder or something that would prevent me from doing something like that.  However, all that said, I've been unable to get the thing to move at all.

In general, this whole piece feels like someone had it before me, did a bad job of working on it and ultimately just bunged it all back together in a haphazard way and passed it on to be someone else's problem.

[HectorLooi]

Looks like someone forced in a screw that was bigger than the hole. 

You would probably need to drill it out with a tungsten carbide rod sharpened at the tip to look like a spade drill. I'll see if I can find a video on how to make one. Start with a 0.5mm rod, then work your way up in 0.1mm increments until the walls of the hole weaken the screw enough to break it up. 

This is a very time consuming, slow process. You'll need to centre the hole properly and not deviate. WD40 helps.

The other option is to abandon the hole and use a dial dot. As much as I hate dial dots, this might be the safest option for a beginner. 

Ok, found it.

 

[DDean]

5 hours ago, HectorLooi said:

The other option is to abandon the hole and use a dial dot. As much as I hate dial dots, this might be the safest option for a beginner. 

Ok, found it.

So that is what the last person to work on this movement appears to have done.  There was a "wad" of adhesive material in the vicinity of that hole when I took the dial off.  I was hoping to take the high road and fix the issue in the work I did on this movement.

I wasn't sure if I was imagining things or not when I looked at the screw hole, but it does appear to be somewhat distended.  I had not considered the posibility that someone had forced a screw that too big in there.  I had wondered about using a technique I've applied in other applications (where the screws are in the same scale as human hands) that involves counter drilling the plug with a  reverse threaded tap.  When I've had to do that in the past, the screw has generally caught and backed out from the torque on the tap (instead of yielding and letting the tap bore into it.)  I don't like doing that, but it's saved my rear a couple of times, but the smallest bolt I've tried that on had a 5 mm head.  This is an entirely different ball of wax.

I am still contemplating disolving the screw with alum, even if that means I have to stick the dial down with double sided tape until I gain the skills to actually replace the screw.

[nevenbekriev]

Yes, the screw seems to be forced in the smaller hole. In such case the screws will not unscrew when drilled with reverse drill bit. You option is to dissolve it. And yes, it is possible to drill a hole in it, then to press tappered broach in and try to unscrew, but it is much harder way.