HOROTEC MSA 07.115 Case Crab

Trying to open my Seamaster 1/100th second chronograph with 10 Lap Memory was such a pain, I decided to buy a professional tool to more easily open snap-on watch case backs. This tool costs around USD 180 (2006) and can return its investment in a short time if you are going to open a lots of of snap-on case backs. I really do not like snap-on case backs too much because it was really hard and stressing work. I am terrified of leaving opening marks and hope that this neat little machine will help me to open my quartz watch backs with more peace of mind.
Thanks John Davis for hinting that this tool also does a great job for bezels. And thank you also for reminding that if the case back does not move, that one simply turns the watch a bit and gives another try.

However, there are still many snap-on watches I open with my all-time favorite simple Bergeon opener. If the snap-on case back has a groove that is big enough for the tool tip of this really great and simple opener, then it will be my first choice. The HOROTEC is for watch case backs that have no grooves or cases that do not allow the Bergeon "heel" to be rested when prying the case back open.

How to use it?
Place either two claws or the white retainer and one claw into the holders. I always wear a loupe and watch what is happening to the watch back while closing the distance between claw and retainer turning the hand wheel on the right. Once the claw is between case and case back the case will pop-open in most cases. If it does not, then use the little metal bar (bottom right), slide through the hole at the end of the claw (sorry, the picture does not show that hole clearly) and carefully wiggle the claw a bit to the right and left. Now you want to make sure that your left hand holds the watch down, there is a spring below the green pad and if you are not careful, the watch would move up and the case might get scratched by the claw. Normally a very slight turn off the claw will pop the back open.

Careful!
You do not need to apply a very high torque on that hand wheel! You might damage the watch case or case back. That is why I am wearing a loupe and observe the claw while I am closing the distance very slowly. If the claw does not move under the case back, then check again whether the claw is flat on the watch case. If the claw grabs either the watch case or the case back, it will not glide in between but simply leave ugly marks.

Hint
The claws from the factory are too sharp. You might easily scratch your cases or case backs. I used an Arkansas stone to take off the very sharp edges of the claws. Also a diamond disk will do of course, or if nothing else is at hand, the finest sandpaper.