Seiko 7A38 - by the numbers

a1topdog at August 31, 2018 at 8:19 AM

What size hand fitting tools do you recommend?

I splashed out and bought the fancy set of 3 by A*F. Covers all 7Axx sizes. 

But other people have been known to get by, just using an old plastic Bic biro with the ball removed (suitably reamed to size). Cheapskates. 

When talking about hands: What kind of tool do you use to remove the small hands? I find a Presto style tool too big. Could imagine using hand levers (1mm).

I personally use these Horotec (Swiss) hand removing levers - the 1.0mm size.

http://www.cousinsuk.com/product/hand-removing-levers-horotec-swiss

You can buy cheaper pairs, but these are superb quality and cost little more than a set of replacement hands (that you might otherwise ruin).

Incidentally, if you need to remove sub-dial hands from a few models whose hands have artificially large decorative bosses - e.g. 7A38-6050, -6060 and -6070, you still use 1.0mm levers. There's no point in using anything larger, because it's not the hand itself you should be levering against, but the underside of its retaining collet.

There's a prime example of 'how not to do it' in the 7A38-6050 model thread.

Ouch, that hurts

Seiko7A38 at February 12, 2012 at 12:20 PM

Something else you should get yourself, Simon (if you haven't done so already) is a Dust Puffer: 

Invaluable for blowing microscopic bits and dust / lint out of a watch case, before you reassemble it.

You can also use it for blowing any dust off a dial / movement before you pop it back into the case - though care is needed, on how close you hold it, because if you get carried away, there is a risk you might dislodge any loose / flaky lume from the hands or dial.

Here's a 'blast from the past' ....

Sadly, not all tools last for ever. I've used my trusty old Dust Puffer on just about every watch I've worked on over the last 10 years - and also, when I remember to, before taking wrist shots. Lately I've noticed small orangey-red specks on the back of a crystal - annoyingly, as I did this morning, when I reassembled my 7A38-701A.

The rubber bulb of my Dust Puffer is perished and has started to disintegrate. 

Time to throw it away and buy a new one. 

Famous last words !! I am feeling extremely annoyed with myself, this afternoon.

That's a minor understatement (without the multiple expletives).

I was in the final stages of reassembling a watch, but before I tightened up the case-back, I thought I'd just have one last check under the magnifier, to see if there were any bits of dust or lint on the dial or back of the crystal, that I'd missed. Sure enough, there was a tiny speck of something or other on the dial, so I unscrewed the case-back and popped the dial / movement out again. In a momentary lapse of concentration, instead of reaching for the Rodico, I picked up my 10-year old dust puffer (per above, which I should have replaced months ago) and pointed it in the direction of the dial / movement in my left hand and gave a quick sharp squeeze.

The brass nozzle flew out of it, just like a bullet and smote the dial !!!