Top Hole Screws

[Dave54]

I've got one of the watch openers with 3 pins. As you say, too big. That one I've linked to goes down to 10mm, and it looks as if a bit of file work would make it fit smaller between centres. The pins could be ground down if needed in a drill chuck with a Dremel or similar.
I think you're looking at modding or making something rather than an off the shelf buy.

 

[JohnD]

using a drill chuck like a lathe is a good idea. I suppose I could spin the pins against a file or a stone.

 

[Dave54]

I picked the idea up from somewhere when I was a teenager. turned lots of small bits down that way. Obviously be careful about having handles on files and not catching sleeves or anything on the chuck etc.

 

[Deleted member 174758]

Just to be a PIA there is a tool called an adjustable pin spanner which can do this job and years nacjk Belzer in Germany did quite a range with different sized pins. Of course Belzer are no more, although Snap-On did take over most of the hand tool side of the business when Sandvik divested themselves of the saws and hand toos business in 1999

 

[rsgaz]

And the pin size is very small.

Wouldn't some circlip pliers do the trick then?

http://www.ebay.co.uk/itm/251878448334

Get the bent version like these for applying more torque than straight ones.

Gaz

 

[JohnD]

I have some like that, but the holes are small and the screws are tight. My lens wrench (smallest spikes) bent when I tried. A lens wrench has two parallel legs that can be slid along crossbars for distance, and has a selection of tips of different sizes, so is equivalent to the "dividers" method. The legs and bars are fairly sturdy, but I need a stronger tool, and short pins so they are less liable to bend. The screws may have been done up very tightly, 70 years ago, with a friction grease that has now hardened. The screws are steel but I don't yet know what metal they go into.

I ordered an adjustable pin-spanner from Germany yesterday, it has 1.5mm pins so may fit some of the screws.