Appropriate tool to cut (widen) slot for lever set

[mbwatch]

I am assembling a 16 size RR pocket watch. The case I have for it is a Fahys oresilver lever set case, but the lever slot starts at about the 7min position. My movement's lever is at 6min and so I want to widen the slot a little bit.

From what I have read, this was a routine operation by jewelers casing up movements. But I can't find reference to the right tool to cut the nickel alloy clean and square without damaging the bezel thread. Diamond file? Straight or rounded? A hobby razor saw (like you'd use to cut model railroad track) seems workable. Dremel seems too dangerous to remove horizontally even though it would be easy to make a clean vertical cut initially.

Thoughts?

[Neverenoughwatches]

For those of us that dont pocketwatch play mb what would be looking at ?

[watchweasol]

Hi.  Pictures would be a great help here to see and understand your predicament.

[mbwatch]

3 hours ago, Neverenoughwatches said:

what would be looking at

Sorry - I forget that this is mostly only an American pocket watch thing.

That notch cut at around the 7min mark needs to be widened about 1.5mm toward the pendant to accommodate a Hamilton setting lever. So I need to cut away a little chunk of the lip there, but the whole circumference is finely threaded for the screw on bezel.

This one was probably factory cut initially, but I have seen loads of others with notches obviously cut by hand tools and some very crudely. The goal is to remove a little metal from that lip, preserve the threads, and ideally not have it look too bad since this is to be a gift eventually. The case is "oresilver" which I believe was a trade name for a nickel-copper alloy. I think it's harder than brass but not nearly as hard as steel.

The threads:

[oldhippy]

There are many types of needle files that you can use for this. 

[AndyGSi]

Depending how hard it is I'd be looking to take most of the material away
with a standard square file and then finish with a diamond file.

[Neverenoughwatches]

49 minutes ago, mbwatch said:

Sorry - I forget that this is mostly only an American pocket watch thing.

That notch cut at around the 7min mark needs to be widened about 1.5mm toward the pendant to accommodate a Hamilton setting lever. So I need to cut away a little chunk of the lip there, but the whole circumference is finely threaded for the screw on bezel.

This one was probably factory cut initially, but I have seen loads of others with notches obviously cut by hand tools and some very crudely. The goal is to remove a little metal from that lip, preserve the threads, and ideally not have it look too bad since this is to be a gift eventually. The case is "oresilver" which I believe was a trade name for a nickel-copper alloy. I think it's harder than brass but not nearly as hard as steel.

The threads:

Nothing more that a small needle file needed. Preferably with one non toothed edge so no risk of the depth being reduced at the same time. To remove the teeth marks, use a square degussit stone will smooth it off nicely or fine ally oxide paper/low grit lapping film glued to a matchstick.

[AndyGSi]

32 minutes ago, Neverenoughwatches said:

Nothing more that a small needle file needed. Preferably with one non toothed edge so no risk of the depth being reduced at the same time. To remove the teeth marks, use a square degussit stone will smooth it off nicely or fine ally oxide paper/low grit lapping film glued to a matchstick.

Strange how different people think but originally I would have gone from the top down but
your idea of just expending it with a small flat safe edge file would probably work better.

[mbwatch]

3 minutes ago, AndyGSi said:

Strange how different people think but originally I would have gone from the top down but
your idea of just expending it with a small flat safe edge file would probably work better.

This is what I was going to ask - did you mean top down or start from inside the existing notch. I was just looking for a file with a clean edge (no prior knowledge of file nomenclature). I will probably take the inside approach rather than top down. Thanks!

[Neverenoughwatches]

2 hours ago, AndyGSi said:

Strange how different people think but originally I would have gone from the top down but
your idea of just expending it with a small flat safe edge file would probably work better.

Maybe thats a joiner's thing ? Having a file rest in the bottom of the notch and removing material sideways just seems a safe option to prevent wander and to keep the cut perpendicular .

2 hours ago, mbwatch said:

This is what I was going to ask - did you mean top down or start from inside the existing notch. I was just looking for a file with a clean edge (no prior knowledge of file nomenclature). I will probably take the inside approach rather than top down. Thanks!

Andy means file from the top into the notch. I took the ' if i aint on the ball i'll balls this up approach ' either way will work just depends how focused you are doing it. I like precaution these days the old eyes and hands aren't what they used to be lol.

[tomh207]

Dredging up some distant memories, I would widen the slot rather than go top down and risk damage to the bottom of the slot. Check the hand safe edge (proper term) cheaper files can have rough edges to this side and need stoned down to smooth it off and prevent marking.

 

Tom

[SwissSeiko]

Yes you should use a barrette file. It has no side cutting teeth. Its one of my favorite files.

[mbwatch]

So I was overly concerned about damaging the threads. I spent less than 5 minutes with a barette file and sized the notch roughly where it needs to be and later I will finish it more to flatten the bottom and square up the side with a fine grit diamond file. But my cut is on the following side of the thread gap so there is no issue with the bezel missing a damaged thread after it crosses the gap.