Closing a 100m water resistant snap back case

[Titanium]

I offered to replace the battery in a friends Tissot watch witch is water resistant to 100m and this is an offer I'm regretting having made. I thought it would be a screw back but it's a snap on back. I successfully got it open and changed the battery but I can't get the thing closed. Am I doing something wrong? I've followed all the guides I can find and it still won't close. I don't like blaming my tools but I got my case press three years ago for £20 and if I'm not the issue (which I might be) could it be the press? I've attached photos of the watch.

This bring me onto question 2. If it is my press then it's time I get a new one. What would people recommend? I was thinking Robur (as i got a set of dies for £17 on eBay) however I'm not sure it has a screw function so pressure can be gently applied or a Horotec as they look good and have the screw down function. Any recommendations would be good.

 

 

[Marc]

Don't try using those dies on a snap on case back, they are designed for installing acrylic crystals. They are made out of bakelite which is fine for acrylic crystals but if you use them for glass crystals or for snap on case backs the rim of the die will flake away, ruining it. They just aren't tough enough to cope with the greater forces involved.

Robur used to do a set of aluminium dies which would work.

[Titanium]

5 minutes ago, Marc said:

Don't try using those dies on a snap on case back, they are designed for installing acrylic crystals. They are made out of bakelite which is fine for acrylic crystals but if you use them for glass crystals or for snap on case backs the rim of the die will flake away, ruining it. They just aren't tough enough to cope with the greater forces involved.

Robur used to do a set of aluminium dies which would work.

Thanks for letting me know. I was considering buying a Horotec 07.131 watch press which comes with derlin dies ( https://www.cousinsuk.com/product/press-screw-on-push-fit-dies ). Would it work? It is advertise as being for snap back cases?

[watchweasol]

Some of these case backs can be very tight to get off and even tighter to get on , a screw press with the nylon/delrin dies worked for me as you can control the pressure with the screw. as the attache below.  left hand one is a Horotec at 90.00 pounds and the right hand on is a chinese copy as about £50.

[Titanium]

Thanks. I've got one last question. Should both the upper and lower dies have sloping sides so everything self centres?

[Klassiker]

Ideally, yes. But choose diameters which make contact with parts of the case and back which will withstand the pressure. On the back, try and find a die which has a contact ring similar in diameter to the snap-in flange. If it's too big it might bottom out before the back snaps in. Too small and you will make the back concave.