Broken Minute Hand - Help !

[Michael20]

Hello all, my latest project is a Uhrenfabrik Villingen Maurer Pfaff & Maier clock (pics attached) the face is marked DRP No 94099 which I think is a German patent number issued in 1897.

I have the clock running and striking perfectly, but this morning disaster struck whilst setting the time - the minute hand snapped. I suspect this is due to a previous repair having failed as I can see what looks like a small brass tab on the reverse (see pics)

I have tried soldering the 2 pieces back together but this obviously isn't going to be strong enough. Any suggestions about the correct way to effect a lasting repair would be greatly appreciated.

 

[AndyGSi]

I think your only option looking where it's broken is to get another hand that can be cut and then solder/braze the old one on top.

[oldhippy]

I would clean it up. Cut a little slot where it goes into the piece that has the square and solder a small brass plate to to hold the two parts together. Yes you are right it is a German Strike and it has inside count wheel strike, should be 8 day duration. People break hand off because they move the hand by the tips or ends always move from the center.  

[praezis]

A fresh breakage I would quickly silver solder or have it laser welded.

Both no more possible with soft solder on the parts.

[watchweasol]

Hi given we assume you have no access to a laser welder, silver solder is the next best option but failing that the method as described by old hippy is the more common method. But clean up and tin both joints before soldering together.

[Michael20]

Thanks all, really appreciate the input. My son has  just offered to take it into work, they restore pre-war cars and are used to dealing with this sort of thing, if they can't fix it I'll try OH's method.

[transporter]

I agree with OH, I have successfully repaired longcase hands using a brass plate and solder. Every joint must be spotlessly clean to ensure a nice repair. Can I ask what temperature silver solder  the other members are using?

I use the paste from a syringe and that requires a temperature far greater than a clock hand could withstand before being workable  

[praezis]

Silver solder needs about 700 deg C.

You can get soft, medium, hard variety with increasing temperature.

[AndyGSi]

53 minutes ago, praezis said:

Silver solder needs about 700 deg C.

You can get soft, medium, hard variety with increasing temperature.

700 Deg C seems way too high so not sure what you're using.

I've used Silver Solder designed for PCBs in the past which is way lower.

 

 

[praezis]

35 minutes ago, AndyGSi said:

700 Deg C seems way too high so not sure what you're using.

I've used Silver Solder designed for PCBs in the past which is way lower.

You don‘t use silver solder but tin solder with a tiny amount of silver in the alloy.

Totally different kind of soldering, not able to withstand any load.

Silver solder is used with a torch.

Frank

[RichardHarris123]

[oldhippy]

Providing it is all nice and clean soft solder will do.

[Michael20]

Not sure what type of solder they used but my son's boss repaired the hand and its back on the clock - have noted OH's comment about not moving the hand by the tip, thanks OH, won't fall for that again.

[transporter]

Thanks for the clarification on the solder, I must say when I silver solder as taught by my mentor I have a dab of silver solder paste on the job and then i need to heat the job until its glowing red, then the solder melts whilst red hot, once melted its off for dip to cool it.

I was thinking that it was soft solder used for hands as thats what i use.