Need some Help, Spanner head screwdriver.

[gill1967]

I have just purchased my first pocket/fob watch and I am desperate to 'get a look under the bonnet' but the crown wheel has a spanner head screw which I need a screwdriver that fits to remove it. I had some modern spanner head bits but they are a no go.

I have looked on a number of websites...including Cousins and I am struggling to find spanner head screwdrivers for this type of watch screw.

Does anyone have any suggestions. Picture of movement attached.

Regards

Paul 

[nickelsilver]

There were tools made for this, and barrel arbors too (in many old watches the hook was on a female threaded ring that screwed to the integral arbor/ratchet). Somewhere in a drawer I have some. But I've always used blunt nickel tweezers. That nut is usually not all that tight.

There are small round jawed jewelers pliers that can fit with a little modification of the tip too.

[sstakoff]

16 minutes ago, nickelsilver said:

But I've always used blunt nickel tweezers. That nut is usually not all that tight.

yep - that's how I do it too

[oldhippy]

If you have a pair of very thin round nosed pliers that will do it. Cut down an old pair of tweezers to a snub nose. I had a tool for this which was like a two pronged screwdriver which I could adjust the width to the holes. Never seen one in years.   

That movement is known as a five bar movement. It is a cylinder so there are no pallets; you have to let all power off before removing the balance. I expect it is Swiss made.  

[AndyHull]

Could you not simply modify a flat bladed screwdriver with a file or fretsaw blade to put a slot in it, something like these hex bits, only presumably a little smaller.

Alternatively if you want something more like OH describes, look on ebay for small circlip pliers, they typically have interchangeable bits with round tips. One final suggestion, superglue (or epoxy) two pins or sewing needles to a piece of hardwood or rigid plastic at the correct distance apart, then file the points flat to avoid scratching the wheel below with them.

Edited January 26, 2019 by AndyHull

[AndyHull]

One other thing that occurs to me. There may be a reason they have used that arrangement. It is possible that the bolt is reverse threaded, so take care when trying to loosen it, it may be lefty tighty, righty loosey rather then the more convention righty tighty etc.

[HSL]

These cylinder movement sometimes can be a bit temperamental and maybe not the best to  start of with but mostly they are a great fun.
That kind of nut was very popular with makers like Remontoir. The movements usually is in a good shape but the watch cases often seen better days since back in the days everyone was a "Watch maker" and tried to service the watch by over oiling things.
Here is a picture to clarify how to remove it with a pair of tweezers. It mostly comes of like a normal right threaded nut.
Just slightly push downwards while turning it.

[StuartBaker104]

You will see another thread on this question here https://www.watchrepairtalk.com/topic/6499-pig-nose-or-snake-eyes-or-spanner-driver-help/#comment-96309

If this is your first cylinder movement, then one word of warning: make sure you have definitely let down all the power from the mainspring before removing the balance, otherwise the train will spin away and you may cause bad things to happen

Enjoy!