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Tips for removing "snap off" watch back

9K views 7 replies 5 participants last post by  aesmith 
#1 ·
Hi,

My Accurist needs a new battery. I view it as not valuable enough for me to want to send it away, but too nice for me to want to risk damage. It's the sort of back that has a little opening for the opener.

When I've opened other snap off backs in the past it's always been a bit of a bodge, using a small screwdriver and a little more force than I'm happy with. That's been OK because these have been junk or novelty watches, or so beat up that a few scratches on the back are neither here nor there. So I'd like to improve my technique so I can open this without damage.

I've had no success so far with any sort of knife, I'm not sure if that's technique or not using the right knife. It always feels as if the blade isn't sharp enough to engage with the slot.

Any tip?

Thanks, Tony S
 
#2 ·
I've found it's worth buying a 'cheap' watch repair kit off e-bay for about £10. Gives you most tools to do simple repairs without worrying. It includes a 'flat' curved knife for getting off watch backs. Also so simple tools for replacing spring bars etc. Not great quality but good enough particularly if you have a few watches pass through your hands.
 
#3 · (Edited by Moderator)
Thanks. I've done something similar, and supplemented with better quality as and when. For example the generic plastic handled spring bar tool now has a genuine Bergeon fork end. The set came with a case knife, something like this https://www.ebay.co.uk/itm/Watch-Opener-Knife-Back-Case-Removal-Battery-Change-Repair-Tool-RED/153387529185

However it doesn't seem to engage the slot at all on any watch I've tried. Do you think it's a matter of sharpening it until it does, then giving it a polish so it doesn't scratch? Or is this an application where a better quality tool is needed.
 
#4 ·
Thanks. I've done something similar, and supplemented with better quality as and when. For example the generic plastic handled spring bar tool now has a genuine Bergeon fork end. The set came with a case knife, something like this https://www.ebay.co.uk/itm/Watch-Opener-Knife-Back-Case-Removal-Battery-Change-Repair-Tool-RED/153387529185

However it doesn't seem to engage the slot at all on any watch I've tried. Do you think it's a matter of sharpening it until it does, then giving it a polish so it doesn't scratch? Or is this an application where a better quality tool is needed.
Sharp knife is the answer, a penknife or even a Stanley knife. I watched a retired watchmaker pop the back off a watch that had defeated me, holding the watch in the palm of one hand, Stanley knife in the other.

If you're worried about your hand, wear gloves. But you shouldn't be pushing that hard.

I have a cheap tool kit. The case knife is completely useless.
 
#5 ·
Cheers. My much abused and battered Lorus needs a battery as well, so I'll have a practice on that. I'm sure I can find an old penknife to modify a little. If it needs to be sharp the cheap Ebay tool's probably no good as won't be hard enough (at a guess).
 
#7 ·
Put some masking tape over the lugs or the part you're levering against to prevent scratching the case. Case knives are not meant to be razor sharp, but most need a little touch with a grindstone in order to get them to fit under the tab or notch on the caseback. Once the blade engages, use a rolling motion to open the back...don't lever the handle upwards or the tip of the knife might scratch the case. Difficult to explain, but this short video shows it perfectly.

 
#8 ·
Thanks everyone, the back's off now using the blade on a multi tool, the blade had enough curvature to get into the slot. No damage visible to the naked eye, or even with 5X loupe, although it's amazing how many other little dings and scratches elsewhere. No mystery about why the watch stopped either, the battery only reads 0.79V. New Renata 377 on order.
 
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