Adjustable banking pins stripped thread in main plate

[Seth]

Good Morning to you all and I hope you are all keeping safe and well during this tough time.I have a pocket watch that runs very rough and on inspection I have found that one of the adjustable banking pins had been replaced by a copper slug and a short piece of wire for the actual pin.On removing this I found the threads in the main plate were stripped.Should I plug the stripped hole with a brass plug then drill and tap out to accept a spare adjustable banking pin or how would you go about repairing this plate.Any suggestions would be gratefully received.Regards to all Seth.

[oldhippy]

I think a nice clear photo is needed so we can see what you are up against. Sounds like a bit of a bodged job. What do you mean by it runs very rough?

[Seth]

7 minutes ago, oldhippy said:

I think a nice clear photo is needed so we can see what you are up against. Sounds like a bit of a bodged job. What do you mean by it runs very rough?

Hi there,Many thanks for your reply,as you will see there is a small copper slug with a fine piece of wire that was pressed into the stripped hole in the main plate.I have a couple of spare adjustable banking pins from old scrap movements and would like to fit one of these into the main plate if it's possible.You will see the hole in the main plate where I have removed the copper slug with my Bergeon Screw Removal tool.Regards Seth.

[nickelsilver]

There are a few issues; your replacement pin likely has an "odd" thread that may or may not match something on the old Martin screwplates, and may or may not be close enough to work with a modern metric thread, but you will quite likely have a hard time finding a tap to match. If it matches a Martin plate you can make a tap. If the new pin's threaded portion is close in size to this one you will need to open the hole significantly to get a decent plug in to rethread, which would be unsightly.

 

The easiest route would be to retap the hole with the closest metric size that will get some threads in there, then make a new pin. To make the pin you can hold some barstock in an oversize collet and insert a bit of copper or other thin metal on one side to get the eccentric. Turn the pin, then holding it normally in a collet cut the thread, part off, then slot. When you tap the hole just go a little at a time, as the tap will be tapered at the tip, you can check with the new eccentric and find the amount of thread that lets you screw it in but have some friction when its at the right depth.

[Seth]

6 minutes ago, nickelsilver said:

There are a few issues; your replacement pin likely has an "odd" thread that may or may not match something on the old Martin screwplates, and may or may not be close enough to work with a modern metric thread, but you will quite likely have a hard time finding a tap to match. If it matches a Martin plate you can make a tap. If the new pin's threaded portion is close in size to this one you will need to open the hole significantly to get a decent plug in to rethread, which would be unsightly.

 

The easiest route would be to retap the hole with the closest metric size that will get some threads in there, then make a new pin. To make the pin you can hold some barstock in an oversize collet and insert a bit of copper or other thin metal on one side to get the eccentric. Turn the pin, then holding it normally in a collet cut the thread, part off, then slot. When you tap the hole just go a little at a time, as the tap will be tapered at the tip, you can check with the new eccentric and find the amount of thread that lets you screw it in but have some friction when its at the right depth.

Hi there Many thanks for your reply,I think after I have completely stripped and put the movement through my Watch Cleaning Machine so that I can see what I am dealing with I will possibly turn a new eccentric pin on my Lorch lathe and retap the hole in the main plate with a metric size so that the new pin will fit to the plate.Regards,Seth.