I just wanted to be sure, because you didn't say they were new hands, but just being fitted for the "first time" - is that the first time on your watch, first time on any watch? Since this is in the vintage section, I didn't want to assume these were brand new hands...
First off, it's not totally unusual to have to broach new hands to get them to fit properly. However in my experience the only two hands on Speedmaster that I've ever had to do this with is the minute recording hand, and the central seconds recording hand. I don't believe I've ever had to broach the hour hand, minute hand, or either of the other sub-dial hands.
So the amount of material being removed is usually very small, unless you are trying to fit a hand that really wasn't made for the watch you are trying to fit it on. This isn't a Speedmaster hand, but this is the sort of broach I would be using for the two hands I would typically have to broach for a Speedmaster - it's finer than any needle you have ever had...
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This is a steel hand, so much more difficult to ream than the soft hands on a Speedmaster, but there is very little pressure involved in doing this.
I do have a hand holder for broaching, but to be honest I never use it. it was one of those "must have" tools that ended up being pretty useless in my view. I took this photo of it to show you:
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I put it beside a pair of tweezers for scale, but the whole thing is about 22 mm long, so less than an inch. It's spring loaded, so you pull the two knurled disks apart, put the hand in between them with the hole in the hand lining up with one of the holes in the disks, and then you turn a part that goes on the threads you see there (mine is missing at the moment) to clamp the hand firmly, and put the reamer through the hole to ream out the hand. Looks like this in use - photo I found on the net...
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I quickly learned that this can damage hands just by clamping it in the tool...so I may have used it once I think. I simply hold the hand in my fingers with finger cots on, and gently ream the hand out. You do have to go slow, because reamers will "catch" in the hole if you are too aggressive, and this will cause the hand to want to spin on the reamer - I suspect this is what your watchmaker is referring to when he says the "torque" is what is causing the damage. He's holding the hand in his fingers, it catches, the hand spins, and then there's pressure on the part of the hand where the lume is.
The holder solves that problem, but may damage the hand from clamping, so I just go slowly when doing this job and have never damaged a hand in the process.
Cheers, Al
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