Enlarging watch hands holes

[number98]

Hey guys, I have just bought a pair of hands for my watch from ebay. I knew from the beginning that the gmt won't fit on the movement without some modifications. I did some research on enlarging watch and found out that one needs a broach and a watch hand tool. I was wondering if its possible to secure the hands using the watch hands tool and use a diamond file? Because I searched cousins and my local watch material supplies shop and they do not have the broach that I want which is 1.50mm. Thank you very much.

[clockboy]

Your research is correct. I use a cheap version ( aprox. £7) of the Bergeon style tool & it works fine. A fine broach & remove gently as it is really easy to go to far see pic below:

[number98]

1 hour ago, clockboy said:

Your research is correct. I use a cheap version ( aprox. £7) of the Bergeon style tool & it works fine. A fine broach & remove gently as it is really easy to go to far see pic below:

Thanks for the reply. Unfortunately I don't know where to source the 1.5mm broach as most of the broaching sets comes with a 1.6mm. Also, the broach for enlarging the holes is consider a cutting or a smoothing broach? Thanks!

[clockboy]

There are plenty of suppliers of broaches. Cousins is good also for quality Eternal tools is a good source.

I would use a smoothing broach to remove slowly.

 

https://www.cousinsuk.com/product/0060-to-200mm-german1

https://www.eternaltools.com/watchmakers-smoothing-broaches-set

[number98]

46 minutes ago, clockboy said:

There are plenty of suppliers of broaches. Cousins is good also for quality Eternal tools is a good source.

I would use a smoothing broach to remove slowly.

 

https://www.cousinsuk.com/product/0060-to-200mm-german1

https://www.eternaltools.com/watchmakers-smoothing-broaches-set

Hi thank you for the reply. Unfortunately the link that you had attached doesn't include the 1.50mm.  Because the hands I bought from ebay( I haven't received them), I think the hour hand will fit but the gmt won't. Because on my movement according to ofrei is 1.52mm but the hands I bought is 1.40mm hence the need to enlarge it. Also I would like to ask is the Bergeon 30464 measuring gauge mandatory for this kind of work? Is it ok to work without it as it is quite expensive. Thank you for helping me!

[Marc]

I could be wrong here but if I am then I'm sure that someone will steer me back on the right path.

As far as I know broaches are not parallel sided like reamers, they are very slightly tapered (all of mine certainly are), so you use a broach which will fit the hole to start with and push it progressively further in until you achieve the desired size, measuring as you go so you know when to stop. The taper is so slight that over the fraction of a mm thickness of the hand tube it is negligible.

As CB says, use a smoothing broach. A cutting broach will remove material, potentially weakening the hand, whereas a smoothing broach sort of pushes the material out of the way without removing it.

[Geo]

You're correct Marc, the readers are tapered.  I suspect the 1.6 will be the thick end of the reamer, so this size will probably be the correct one.

As an example, my 2mm reamer is 1.5 at the small end.