7s26 second hand falls off after a few days

[DoctoralHermit]

Hey all! I've got myself my first watchmaking conundrum. I recently did some dial work on my 7s26, and had some trouble putting the hands back on. I think I pressed rather firmly to get the hands on. The watch worked perfectly for about 5 days of rigorous wear, but then the second hand fell off without warning. Any idea what the issue might be?

 

Thanks!

[watchweasol]

Probably slack fit on the pinnion, try putting the tube end in a small pin vise and tighten it up. Do it in minute stages so as not to over do it, keep trying it after each adjustment

[DoctoralHermit]

5 hours ago, watchweasol said:

Probably slack fit on the pinnion, try putting the tube end in a small pin vise and tighten it up. Do it in minute stages so as not to over do it, keep trying it after each adjustment

Thank you! By the "tube end," do you mean the part of the cannon pinion that sticks up, or do you mean the part on the underside of the second hand that fits into the cannon pinion?

[anilv]

The hand-tube needs to be tightened up a bit.

You didn't mention the history of the watch, seiko hands on their normal watches don't usually give problems but if this was a used watch it could be one from a different model bodged to fit.

Anilv

[jdm]

10 hours ago, DoctoralHermit said:

Thank you! By the "tube end," do you mean the part of the cannon pinion that sticks up, or do you mean the part on the underside of the second hand that fits into the cannon pinion?

The cannon pinion doesn't touch the seconds hand, which is driven by the central wheel pivot.

The hand tube is the hollow part part of the hand.

[Tmuir]

As said above you need to tighten (Squeeze) the tube on teh second hand with a fine good quality pin vice.

I just did the same thing to fix a loose Chronogrph second hand on a quartz watch, tighten a tiny bit at a time or if you go too far you will need to broach back out the tube and I'm guessing you wont have broaches that fine.

This was the post I did about tightening the hand.

https://www.watchrepairtalk.com/topic/11849-refitting-a-loose-chronograph-hand/

[Tmuir]

I forgot to add check the tube on the second hand first to see if it has split. If it has split you will need to get a new second hand unless you fancy your odds of riveting on a new tube on the hand

[yankeedog]

A new second hand won't break the bank either.