Soldering a post on the back of an enamelled face?

[geoff]

Hi,

I'm repairing an antique pocket watch made by a craftsman in a small town in North-West Denmark. The face is a typical enamelled metal face, and it used to have two posts that were used to secure it to the movement.

One of those posts is gone - separated at what appears to have been a solder joint.

I'm now debating how to attach a new post to the back of the face. I can turn one from brass - but is there a danger that a soldering iron will melt the enamel on the front of the dial?

Thanks

-geoff

[clockboy]

Yes it will stain/burn the enamel. I recommend you glue the new post with something like JB weld metal epoxy. I advise from bitter experience.  

[vinn3]

  welders that have a lot of experence could solder the dial  feet without any  - stain/burn ?  vin

[geoff]

Thanks for the info. I'll go with an epoxy solution instead of solder - just to be safe.

Cheers

-geoff

[measuretwice]

58 minutes ago, vinn3 said:

  welders that have a lot of experence could solder the dial  feet without any  - stain/burn ?  vin

you must know some great welders, I employ a dozen of them and wouldn't want one near a dial face lol.  

To solder imo you need a resistance solderer which isn't too challenging to make.  The idea is basically create a short of a low voltage source across the joint.  The way its works is the smallest cross section (like where the foot touches the back of dial) is going to heat up very quickly, more quickly than the surrounding material, so in second or less you've heated and melted the joint before the face heats up too much. 

That's the theory, I'm not the voice of experience but have to do one myself so have been reading up on it and starting to build the resistance solderer.  I also plan on using a heatsink on the dial side, like a wet sponge, for extra protection.

 

[clockboy]

This subject has been covered many times on the forum. There is a machine specifically to do this job but it is pricy. See links below from 2015 :

 

 

OR 

http://watchlume.com/DIAL-SOLDERING-MACHINE/Watch-Dial-Feet-Soldering-Machine

[BUSAKAZ]

There needs to be a section on this site like a wiki where you can put all common questions in that will stop this.


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[clockboy]

2 hours ago, BUSAKAZ said:

There needs to be a section on this site like a wiki where you can put all common questions in that will stop this.


Sent from my iPhone using Tapatalk

I found these just using the search facility. 

[vinn3]

good welders know a lot about this. for example,       first you do not use an iron,  use a torch and a wet rag to cool the dial face.  and,    the oxy/acetlene torch includes "jewlers torch".  epoxy and double sided tape are a jury rig for replacing dial feet.   the machine mentioned above sounds interesting  vin

[praezis]

Soft soldering is the way this work is done on enamel dials.

But:

You have to heat the whole dial equally, usually with an alcohol lamp from below. Then there is no danger for the dial. 

Don't use brass wire for the post but copper wire.

Frank

[watchweasol]

Hi Geoff  The resistance solder machine  is expensive if bought but relativly simple to construct using a mains transformer  stepped down  on the out put.  have a look for a book by Wesley R Door on retrofitting when the need arises he has a simple diagram of how to build one.  I made my own using a 12v car battery charger and a box to hold the dial and the copper dial foot, and it works with no marks on the dial face either. There are two types on uses a box with a post to hold the dial foot wire and a platform to attach the dial. If I can find the research notes i got i will post them  I have attached the pages from Door's book regarding the dial foot machine hope all this is some use to you

retrofitting - dial foot.pdf

[watchweasol]

Hi Geoff  Just had a shufty on the net   Dirk Fassbender has a good diagram of one but if you google watch dial foot soldering you will get loads of info of how to build one, they really are quite easy to do. sourcing the bits might need a bit of patience, have fun If you need help just message  me    Iain

[yankeedog]

Sorry , but welding and soldering are two completely different animals.In welding the two pieces are fused , typically melted together so the result is that they are one piece of metal, In soldering the joined pieces are not melted together joined by another metal, solder which has a lower melting temperature than other metals and alloys typically encountered.It should be noted that it is almost impossible to solder aluminum, the surface of which is actually aluminum oxide which prevents the adhesion of solder. The solder alloy with the lowest melting temperature is a 63/37 % tin/lead alloy which melts at 183 degrees C , I have only ever seen it used in military applications.60/40 solder which has 188 degrees C melting point is what is common use everywhere else. Flames and irons used to melt the solder are in excess of those temperatures, If your work cannot tolerate these temperatures without  damage you should not consider soldering.