Problem With Snapping A Snap-On Case Back On

[WillFly]

The 4 free watches I got this morning are little crackers - far better than I expected them to be, with simple but well-made movements and fairly rugged cases. All keeping good time so far and with clean movements. The Chinese Chumei and the Indian HMT Suraf have screw-on cases and were simple for me to uncover, photograph and re-cover. The other two Indian HMTs have parashock cases with snap-on backs. Both were stiff to prise off. One - the Kohinoor - went back OK with the case press, but the other snap-on back will just NOT go on, even with the case press screwed very tightly. I've checked it for position, notches, etc., and can't see a problem. But will it click in? No it won't.

 

Any advice?

[Geo]

Yip!

[WillFly]

:D :D :D

[Geo]

On a serious note, it surely just needs a lot of pressure making sure that it is applied to the outer borders of the case.

[atimegoneby]

 but the other snap-on back will just NOT go on, even with the case press screwed very tightly. I've checked it for position, notches, etc., and can't see a problem. But will it click in? No it won't.

 

Any advice?

Hi Will,

 

I have the same problem at the moment (posted in Armani chronograph) and I actually broke the glass trying !, I think it might be because my press has nylon dies the nylon is flexing and absorbing some of the pressure whereas aluminium dies would not do this, I'm going to try another press or as Geo says

 

''A big hammer'' :pulling-hair-out:

[WillFly]

My press also has nylon dies.

[bobm12]

I use nylon dies and as I said before, the dice have to be selected properly so the pressures apply only on the spots needed, otherwise the crystal breakes or the back shifts and may damage the stem or any other part. It is possible that being nylon they are much more picky than the alluminum ones.

[ro63rto]

My press also has nylon dies.

Is it a hand held press or one of those that look like a drill press?

I have a hand held and find I need to put it on a solid table to lean on it. It too has nylon dies.

[WillFly]

It's a drill press style - on a stand with a screw down press. The watch goes face down on to a die and a die goes on the case back, with the whole lot being compressed by the screw mechanism.

[Geo]

lubricate the back very slightly where it contacts the case and try again with your press.

[bobm12]

[clockboy]

Will,

I have had a few of these bugg**rs I think the back distorts when opened. I found that a smear of silicon grease on its rim and a machine press does the trick. I was told once by a watch repairer that putting the back in a freezer for a while helps as it very slightly shrinks the metal. I have never tried this method but the theory sounds good.

Edited September 17, 2014 by clockboy

[autowind]

I was about to suggest that a bigger hammer was not necessarily the right way to go and was about to suggest a smidgen of grease where the back snaps on but was beaten by other members. Let us know if you get it back on Will. 

[WillFly]

Thanks for the grease heads-up, folks - I'll give it a go!

[Mark]

Thanks for the grease heads-up, folks - I'll give it a go!

 

Im sure I need not say this but make sure your lower die clears the glass.

 

Is your press a lever type or a screw type? I find the screw type to be far more useful for these annoying tight ones as I feel more in control. But keep making adjustments to the position and you should get to the sweet spot.

[WillFly]

Cheers Mark - yes, I've been very careful to avoid pressing the glass, and made several adjustments to the upper die position.

 

This morning, I even inserted a 50p piece between the screw of the press and the top of the upper die - because the pressure was pushing the screw into the plastic upper die rather than exerting its full pressure on the case back. Result? The screw just bored into the 50p piece!

 

So, no more on this until I get the Seiko silicon grease.

[atimegoneby]

 I was told once by a watch repairer that putting the back in a freezer for a while helps as it very slightly shrinks the metal. I have never tried this method but the theory sounds good.

I think I would be wary of this incase condensation forms on the inside of the watch ! 

[bobm12]

Alternatively, heating the whole watch under a torch and leaving the back at room temperature will avoid humidity! :)

 

On a more serious note, I started to think: Maybe the gasket is being pinched while pressing the back on. Did you check the gasket Will? It may be hard to spot in some watches thou.

[Lee]

if you post it to me I'll put it on for you, although with the cost of postage its less than an ideal way!

[WillFly]

if you post it to me I'll put it on for you, although with the cost of postage its less than an ideal way!

That's a very kind offer, Lee, and I may well take it up. I'm seeing a watch repair friend of mine next Tuesday down near Southampton - one of my regular visits where we drink coffee and talk watches for a morning - and I have various little projects for him. I believe he has some silicon grease so I'll take it over with me and we'll see what he can do as he also has various case presses. If he can't succeed, I'll gladly contact you.

[WillFly]

Success with the case back this morning. I went over to see my watch repair buddy in Bursledon and - between us - we managed to get one side of the case back firmly in, with one side still proud. I spotted a small bench vice with 4" jaws attached to the side of his workbench and suggested that, with suitable, padding, that might do the trick.

 

So we put the right plastic dies in place, added some extra dies for safety and, working our way around the rim, used the vice to ease case and back closer together. Finally - with a gunshot sound - the case snapped together! It's never coming off again while I have it!

 

And all the while the watch was ticking away merrily... :woohoo-jumping-smiley-emoticon:

[Geo]

Bloomin heck Will, never had one that tight! Great that you managed.

[bobm12]

Yeah! Way to go Will! Did you check the inscription on the reverse back of the watch, inside it, before closing?...Just kidding! :)

[WillFly]

Yeah! Way to go Will! Did you check the inscription on the reverse back of the watch, inside it, before closing?...Just kidding! :)

:phew:

[Vich]

I bet you heart was in your mouth for that one - sound job Will