New to the group, new to fixing watches. Can't find gasket for my old timex marlin

[CanadiaEh]

Hello 

I have an old Timex Marlin and it's getting a lot of condensation from normal use. I wanted to change the gasket and it looks like this one is damaged. Anyone know the size of where I can get this?

 

Thank you!

[Waggy]

Get some of these, there are a range of sized and thicknesses and are very inexpensive

[clockboy]

Measure the old one and purchase a new one.. Cousins UK would be a good site visit. I recommend you use silicone grease to lubricate the new gasket. 

Edited September 16 by clockboy

[JerseyMo]

Timex guaranteed water resistant for only one year as long as the watch had the original crystal, stem\crown and case back.  Point being made is moisture can also be getting in from the all three.  BUt the case back is a good start.  I use generic rings that came in a multi size package.

[Waggy]

On 9/16/2024 at 11:53 AM, clockboy said:

I recommend you use silicone grease to lubricate the new gasket. 

Fully agree with the above, and a small investment in one of these pads (check out Amazon/eBay/Ali) will take care of greasing the o-rings for you, the siliconed o-ring will also be more 'sticky' and increase the chances of staying where you put without pinging off whilst you get the case etc back into position:

You can also recharge the pads with silicone grease

On 9/16/2024 at 11:53 AM, clockboy said:

Measure the old one and purchase a new one

 

This is easier said than done, perhaps the easiest way is to use a measuring cone:

These can be expensive, but if you have a access to a 3D printer you can make your own:
https://www.printables.com/model/471050-o-ring-sizing-cones/files

To calculate the outside diameter (OD) of the o-ring, you just need to measure its thickness using a caliper or other tool and then use the formula below (credit here):

To calculate an o-ring's outside diameter (OD) you may use this formula: 2(CS) + ID = OD
If you have the OD and need to find the ID use this formula: OD - 2(CS) = ID

 

Another slightly less accurate (but still more than good enough) method to approximate the o-ring size is to cut the old o-ring and then measure its length = circumference...

So diameter of the o-ring = length/π

Finally, o-rings can break fairly easily, dropping them in a cup of hot water will soften them up and allow them to be stretched a little more without breaking - in a pinch I have even used a cup of coffee on an oil rig at 3:00 am in the north sea to do this - you can't always find hot water but you can always find coffee! ha ha.... but not suggesting you use coffee here, before I get strung up, just an amusing anecdote.